| Message ID | 20221115011943.1051039-1-ira.weiny@intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | PCI/doe: Fix work struct declaration | expand |
On Mon, 14 Nov 2022 17:19:43 -0800 ira.weiny@intel.com wrote: > From: Ira Weiny <ira.weiny@intel.com> > > The callers of pci_doe_submit_task() allocate the pci_doe_task on the > stack. This causes the work structure to be allocated on the stack > without pci_doe_submit_task() knowing. Work item initialization needs > to be done with either INIT_WORK_ONSTACK() or INIT_WORK() depending on > how the work item is allocated. > > Jonathan suggested creating doe task allocation macros such as > DECLARE_CDAT_DOE_TASK_ONSTACK().[1] The issue with this is the work > function is not known to the callers and must be initialized correctly. > > A follow up suggestion was to have an internal 'pci_doe_work' item > allocated by pci_doe_submit_task().[2] This requires an allocation which > could restrict the context where tasks are used. > > Compromise with an intermediate step to initialize the task struct with > a new call pci_doe_init_task() which must be called prior to submit > task. > > [1] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m88a7f50dcce52f30c8bf5c3dcc06fa9843b54a2d > [2] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m63c636c5135f304480370924f4d03c00357be667 > > Cc: Bjorn Helgaas <helgaas@kernel.org> > Reported-by: Gregory Price <gregory.price@memverge.com> > Reported-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > Suggested-by: Dan Williams <dan.j.williams@intel.com> > Signed-off-by: Ira Weiny <ira.weiny@intel.com> Looks like a good solution to me. Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > --- > drivers/cxl/core/pci.c | 2 ++ > drivers/pci/doe.c | 14 ++++++++++++-- > include/linux/pci-doe.h | 8 +++++--- > 3 files changed, 19 insertions(+), 5 deletions(-) > > diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c > index 9240df53ed87..a19c1fa0e2f4 100644 > --- a/drivers/cxl/core/pci.c > +++ b/drivers/cxl/core/pci.c > @@ -525,6 +525,7 @@ static int cxl_cdat_get_length(struct device *dev, > DECLARE_CDAT_DOE_TASK(CDAT_DOE_REQ(0), t); > int rc; > > + pci_doe_init_task(cdat_doe, &t.task, true); > rc = pci_doe_submit_task(cdat_doe, &t.task); > if (rc < 0) { > dev_err(dev, "DOE submit failed: %d", rc); > @@ -554,6 +555,7 @@ static int cxl_cdat_read_table(struct device *dev, > u32 *entry; > int rc; > > + pci_doe_init_task(cdat_doe, &t.task, true); > rc = pci_doe_submit_task(cdat_doe, &t.task); > if (rc < 0) { > dev_err(dev, "DOE submit failed: %d", rc); > diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c > index e402f05068a5..cabeae4ae955 100644 > --- a/drivers/pci/doe.c > +++ b/drivers/pci/doe.c > @@ -319,6 +319,7 @@ static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid, > }; > int rc; > > + pci_doe_init_task(doe_mb, &task, true); > rc = pci_doe_submit_task(doe_mb, &task); > if (rc < 0) > return rc; > @@ -495,6 +496,14 @@ bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type) > } > EXPORT_SYMBOL_GPL(pci_doe_supports_prot); > > +void pci_doe_init_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task, > + bool onstack) > +{ > + task->doe_mb = doe_mb; > + __INIT_WORK(&task->work, doe_statemachine_work, onstack); > +} > +EXPORT_SYMBOL_GPL(pci_doe_init_task); > + > /** > * pci_doe_submit_task() - Submit a task to be processed by the state machine > * > @@ -517,6 +526,9 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) > if (!pci_doe_supports_prot(doe_mb, task->prot.vid, task->prot.type)) > return -EINVAL; > > + if (WARN_ON_ONCE(task->work.func != doe_statemachine_work)) > + return -EINVAL; > + > /* > * DOE requests must be a whole number of DW and the response needs to > * be big enough for at least 1 DW > @@ -528,8 +540,6 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) > if (test_bit(PCI_DOE_FLAG_DEAD, &doe_mb->flags)) > return -EIO; > > - task->doe_mb = doe_mb; > - INIT_WORK(&task->work, doe_statemachine_work); > queue_work(doe_mb->work_queue, &task->work); > return 0; > } > diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h > index ed9b4df792b8..457fc0e53d64 100644 > --- a/include/linux/pci-doe.h > +++ b/include/linux/pci-doe.h > @@ -31,8 +31,8 @@ struct pci_doe_mb; > * @rv: Return value. Length of received response or error (bytes) > * @complete: Called when task is complete > * @private: Private data for the consumer > - * @work: Used internally by the mailbox > - * @doe_mb: Used internally by the mailbox > + * @work: Used internally by the mailbox [see pci_doe_init_task()] > + * @doe_mb: Used internally by the mailbox [see pci_doe_init_task()] > * > * The payload sizes and rv are specified in bytes with the following > * restrictions concerning the protocol. > @@ -53,7 +53,7 @@ struct pci_doe_task { > void (*complete)(struct pci_doe_task *task); > void *private; > > - /* No need for the user to initialize these fields */ > + /* Call pci_doe_init_task() for these */ > struct work_struct work; > struct pci_doe_mb *doe_mb; > }; > @@ -72,6 +72,8 @@ struct pci_doe_task { > > struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset); > bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type); > +void pci_doe_init_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task, > + bool onstack); > int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task); > > #endif > > base-commit: 30a0b95b1335e12efef89dd78518ed3e4a71a763
Hi Ira, Can you fix the subject to follow capitalization convention (use "git log --oneline") and say something more specific than "fix struct"? On Mon, Nov 14, 2022 at 05:19:43PM -0800, ira.weiny@intel.com wrote: > From: Ira Weiny <ira.weiny@intel.com> > > The callers of pci_doe_submit_task() allocate the pci_doe_task on the > stack. This causes the work structure to be allocated on the stack > without pci_doe_submit_task() knowing. Work item initialization needs > to be done with either INIT_WORK_ONSTACK() or INIT_WORK() depending on > how the work item is allocated. > > Jonathan suggested creating doe task allocation macros such as > DECLARE_CDAT_DOE_TASK_ONSTACK().[1] The issue with this is the work > function is not known to the callers and must be initialized correctly. > > A follow up suggestion was to have an internal 'pci_doe_work' item > allocated by pci_doe_submit_task().[2] This requires an allocation which > could restrict the context where tasks are used. > > Compromise with an intermediate step to initialize the task struct with > a new call pci_doe_init_task() which must be called prior to submit > task. I'm not really a fan of passing a parameter to say "this struct is on the stack" because that seems kind of error-prone and I don't know what the consequence of getting it wrong would be. Sounds like it *could* be some memory corruption or reading garbage data that would be hard to debug. Do we have cases today where pci_doe_submit_task() can't do the kzalloc() as in your patch at [3]? If the current use cases allow a kzalloc(), why not do that now and defer this until it becomes an issue? Bjorn > [1] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m88a7f50dcce52f30c8bf5c3dcc06fa9843b54a2d > [2] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m63c636c5135f304480370924f4d03c00357be667 [3] https://lore.kernel.org/linux-cxl/Y2AnKB88ALYm9c5L@iweiny-desk3/ > Cc: Bjorn Helgaas <helgaas@kernel.org> > Reported-by: Gregory Price <gregory.price@memverge.com> > Reported-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > Suggested-by: Dan Williams <dan.j.williams@intel.com> > Signed-off-by: Ira Weiny <ira.weiny@intel.com> > --- > drivers/cxl/core/pci.c | 2 ++ > drivers/pci/doe.c | 14 ++++++++++++-- > include/linux/pci-doe.h | 8 +++++--- > 3 files changed, 19 insertions(+), 5 deletions(-) > > diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c > index 9240df53ed87..a19c1fa0e2f4 100644 > --- a/drivers/cxl/core/pci.c > +++ b/drivers/cxl/core/pci.c > @@ -525,6 +525,7 @@ static int cxl_cdat_get_length(struct device *dev, > DECLARE_CDAT_DOE_TASK(CDAT_DOE_REQ(0), t); > int rc; > > + pci_doe_init_task(cdat_doe, &t.task, true); > rc = pci_doe_submit_task(cdat_doe, &t.task); > if (rc < 0) { > dev_err(dev, "DOE submit failed: %d", rc); > @@ -554,6 +555,7 @@ static int cxl_cdat_read_table(struct device *dev, > u32 *entry; > int rc; > > + pci_doe_init_task(cdat_doe, &t.task, true); > rc = pci_doe_submit_task(cdat_doe, &t.task); > if (rc < 0) { > dev_err(dev, "DOE submit failed: %d", rc); > diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c > index e402f05068a5..cabeae4ae955 100644 > --- a/drivers/pci/doe.c > +++ b/drivers/pci/doe.c > @@ -319,6 +319,7 @@ static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid, > }; > int rc; > > + pci_doe_init_task(doe_mb, &task, true); > rc = pci_doe_submit_task(doe_mb, &task); > if (rc < 0) > return rc; > @@ -495,6 +496,14 @@ bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type) > } > EXPORT_SYMBOL_GPL(pci_doe_supports_prot); > > +void pci_doe_init_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task, > + bool onstack) > +{ > + task->doe_mb = doe_mb; > + __INIT_WORK(&task->work, doe_statemachine_work, onstack); > +} > +EXPORT_SYMBOL_GPL(pci_doe_init_task); > + > /** > * pci_doe_submit_task() - Submit a task to be processed by the state machine > * > @@ -517,6 +526,9 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) > if (!pci_doe_supports_prot(doe_mb, task->prot.vid, task->prot.type)) > return -EINVAL; > > + if (WARN_ON_ONCE(task->work.func != doe_statemachine_work)) > + return -EINVAL; > + > /* > * DOE requests must be a whole number of DW and the response needs to > * be big enough for at least 1 DW > @@ -528,8 +540,6 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) > if (test_bit(PCI_DOE_FLAG_DEAD, &doe_mb->flags)) > return -EIO; > > - task->doe_mb = doe_mb; > - INIT_WORK(&task->work, doe_statemachine_work); > queue_work(doe_mb->work_queue, &task->work); > return 0; > } > diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h > index ed9b4df792b8..457fc0e53d64 100644 > --- a/include/linux/pci-doe.h > +++ b/include/linux/pci-doe.h > @@ -31,8 +31,8 @@ struct pci_doe_mb; > * @rv: Return value. Length of received response or error (bytes) > * @complete: Called when task is complete > * @private: Private data for the consumer > - * @work: Used internally by the mailbox > - * @doe_mb: Used internally by the mailbox > + * @work: Used internally by the mailbox [see pci_doe_init_task()] > + * @doe_mb: Used internally by the mailbox [see pci_doe_init_task()] > * > * The payload sizes and rv are specified in bytes with the following > * restrictions concerning the protocol. > @@ -53,7 +53,7 @@ struct pci_doe_task { > void (*complete)(struct pci_doe_task *task); > void *private; > > - /* No need for the user to initialize these fields */ > + /* Call pci_doe_init_task() for these */ > struct work_struct work; > struct pci_doe_mb *doe_mb; > }; > @@ -72,6 +72,8 @@ struct pci_doe_task { > > struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset); > bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type); > +void pci_doe_init_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task, > + bool onstack); > int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task); > > #endif > > base-commit: 30a0b95b1335e12efef89dd78518ed3e4a71a763 > -- > 2.37.2 >
On Tue, Nov 15, 2022 at 01:44:24PM -0600, Bjorn Helgaas wrote: > Hi Ira, > > Can you fix the subject to follow capitalization convention (use "git > log --oneline") > My apologies. I should have capitalized DOE. > > and say something more specific than "fix struct"? How about? PCI/DOE: Fix initialization of work struct in pci_doe_task Thanks for the review, Ira > > On Mon, Nov 14, 2022 at 05:19:43PM -0800, ira.weiny@intel.com wrote: > > From: Ira Weiny <ira.weiny@intel.com> > > > > The callers of pci_doe_submit_task() allocate the pci_doe_task on the > > stack. This causes the work structure to be allocated on the stack > > without pci_doe_submit_task() knowing. Work item initialization needs > > to be done with either INIT_WORK_ONSTACK() or INIT_WORK() depending on > > how the work item is allocated. > > > > Jonathan suggested creating doe task allocation macros such as > > DECLARE_CDAT_DOE_TASK_ONSTACK().[1] The issue with this is the work > > function is not known to the callers and must be initialized correctly. > > > > A follow up suggestion was to have an internal 'pci_doe_work' item > > allocated by pci_doe_submit_task().[2] This requires an allocation which > > could restrict the context where tasks are used. > > > > Compromise with an intermediate step to initialize the task struct with > > a new call pci_doe_init_task() which must be called prior to submit > > task. > > I'm not really a fan of passing a parameter to say "this struct is on > the stack" because that seems kind of error-prone and I don't know > what the consequence of getting it wrong would be. Sounds like it > *could* be some memory corruption or reading garbage data that would > be hard to debug. > > Do we have cases today where pci_doe_submit_task() can't do the > kzalloc() as in your patch at [3]? If the current use cases allow a > kzalloc(), why not do that now and defer this until it becomes an > issue? > > Bjorn > > > [1] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m88a7f50dcce52f30c8bf5c3dcc06fa9843b54a2d > > [2] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m63c636c5135f304480370924f4d03c00357be667 > > [3] https://lore.kernel.org/linux-cxl/Y2AnKB88ALYm9c5L@iweiny-desk3/ > > > Cc: Bjorn Helgaas <helgaas@kernel.org> > > Reported-by: Gregory Price <gregory.price@memverge.com> > > Reported-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > > Suggested-by: Dan Williams <dan.j.williams@intel.com> > > Signed-off-by: Ira Weiny <ira.weiny@intel.com> > > --- > > drivers/cxl/core/pci.c | 2 ++ > > drivers/pci/doe.c | 14 ++++++++++++-- > > include/linux/pci-doe.h | 8 +++++--- > > 3 files changed, 19 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c > > index 9240df53ed87..a19c1fa0e2f4 100644 > > --- a/drivers/cxl/core/pci.c > > +++ b/drivers/cxl/core/pci.c > > @@ -525,6 +525,7 @@ static int cxl_cdat_get_length(struct device *dev, > > DECLARE_CDAT_DOE_TASK(CDAT_DOE_REQ(0), t); > > int rc; > > > > + pci_doe_init_task(cdat_doe, &t.task, true); > > rc = pci_doe_submit_task(cdat_doe, &t.task); > > if (rc < 0) { > > dev_err(dev, "DOE submit failed: %d", rc); > > @@ -554,6 +555,7 @@ static int cxl_cdat_read_table(struct device *dev, > > u32 *entry; > > int rc; > > > > + pci_doe_init_task(cdat_doe, &t.task, true); > > rc = pci_doe_submit_task(cdat_doe, &t.task); > > if (rc < 0) { > > dev_err(dev, "DOE submit failed: %d", rc); > > diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c > > index e402f05068a5..cabeae4ae955 100644 > > --- a/drivers/pci/doe.c > > +++ b/drivers/pci/doe.c > > @@ -319,6 +319,7 @@ static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid, > > }; > > int rc; > > > > + pci_doe_init_task(doe_mb, &task, true); > > rc = pci_doe_submit_task(doe_mb, &task); > > if (rc < 0) > > return rc; > > @@ -495,6 +496,14 @@ bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type) > > } > > EXPORT_SYMBOL_GPL(pci_doe_supports_prot); > > > > +void pci_doe_init_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task, > > + bool onstack) > > +{ > > + task->doe_mb = doe_mb; > > + __INIT_WORK(&task->work, doe_statemachine_work, onstack); > > +} > > +EXPORT_SYMBOL_GPL(pci_doe_init_task); > > + > > /** > > * pci_doe_submit_task() - Submit a task to be processed by the state machine > > * > > @@ -517,6 +526,9 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) > > if (!pci_doe_supports_prot(doe_mb, task->prot.vid, task->prot.type)) > > return -EINVAL; > > > > + if (WARN_ON_ONCE(task->work.func != doe_statemachine_work)) > > + return -EINVAL; > > + > > /* > > * DOE requests must be a whole number of DW and the response needs to > > * be big enough for at least 1 DW > > @@ -528,8 +540,6 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) > > if (test_bit(PCI_DOE_FLAG_DEAD, &doe_mb->flags)) > > return -EIO; > > > > - task->doe_mb = doe_mb; > > - INIT_WORK(&task->work, doe_statemachine_work); > > queue_work(doe_mb->work_queue, &task->work); > > return 0; > > } > > diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h > > index ed9b4df792b8..457fc0e53d64 100644 > > --- a/include/linux/pci-doe.h > > +++ b/include/linux/pci-doe.h > > @@ -31,8 +31,8 @@ struct pci_doe_mb; > > * @rv: Return value. Length of received response or error (bytes) > > * @complete: Called when task is complete > > * @private: Private data for the consumer > > - * @work: Used internally by the mailbox > > - * @doe_mb: Used internally by the mailbox > > + * @work: Used internally by the mailbox [see pci_doe_init_task()] > > + * @doe_mb: Used internally by the mailbox [see pci_doe_init_task()] > > * > > * The payload sizes and rv are specified in bytes with the following > > * restrictions concerning the protocol. > > @@ -53,7 +53,7 @@ struct pci_doe_task { > > void (*complete)(struct pci_doe_task *task); > > void *private; > > > > - /* No need for the user to initialize these fields */ > > + /* Call pci_doe_init_task() for these */ > > struct work_struct work; > > struct pci_doe_mb *doe_mb; > > }; > > @@ -72,6 +72,8 @@ struct pci_doe_task { > > > > struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset); > > bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type); > > +void pci_doe_init_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task, > > + bool onstack); > > int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task); > > > > #endif > > > > base-commit: 30a0b95b1335e12efef89dd78518ed3e4a71a763 > > -- > > 2.37.2 > >
On Tue, Nov 15, 2022 at 12:18:38PM -0800, Ira Weiny wrote: > On Tue, Nov 15, 2022 at 01:44:24PM -0600, Bjorn Helgaas wrote: > > and say something more specific than "fix struct"? > > How about? > > PCI/DOE: Fix initialization of work struct in pci_doe_task The importance of this has to do with whether something is on the stack, so I think something about that would be useful. I'm afraid this subject line bike-shedding has made you overlook my other questions below ... > > On Mon, Nov 14, 2022 at 05:19:43PM -0800, ira.weiny@intel.com wrote: > > > From: Ira Weiny <ira.weiny@intel.com> > > > > > > The callers of pci_doe_submit_task() allocate the pci_doe_task on the > > > stack. This causes the work structure to be allocated on the stack > > > without pci_doe_submit_task() knowing. Work item initialization needs > > > to be done with either INIT_WORK_ONSTACK() or INIT_WORK() depending on > > > how the work item is allocated. > > > > > > Jonathan suggested creating doe task allocation macros such as > > > DECLARE_CDAT_DOE_TASK_ONSTACK().[1] The issue with this is the work > > > function is not known to the callers and must be initialized correctly. > > > > > > A follow up suggestion was to have an internal 'pci_doe_work' item > > > allocated by pci_doe_submit_task().[2] This requires an allocation which > > > could restrict the context where tasks are used. > > > > > > Compromise with an intermediate step to initialize the task struct with > > > a new call pci_doe_init_task() which must be called prior to submit > > > task. > > > > I'm not really a fan of passing a parameter to say "this struct is on > > the stack" because that seems kind of error-prone and I don't know > > what the consequence of getting it wrong would be. Sounds like it > > *could* be some memory corruption or reading garbage data that would > > be hard to debug. > > > > Do we have cases today where pci_doe_submit_task() can't do the > > kzalloc() as in your patch at [3]? If the current use cases allow a > > kzalloc(), why not do that now and defer this until it becomes an > > issue? > > > > Bjorn > > > > > [1] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m88a7f50dcce52f30c8bf5c3dcc06fa9843b54a2d > > > [2] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m63c636c5135f304480370924f4d03c00357be667 > > > > [3] https://lore.kernel.org/linux-cxl/Y2AnKB88ALYm9c5L@iweiny-desk3/ > > > > > Cc: Bjorn Helgaas <helgaas@kernel.org> > > > Reported-by: Gregory Price <gregory.price@memverge.com> > > > Reported-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > > > Suggested-by: Dan Williams <dan.j.williams@intel.com> > > > Signed-off-by: Ira Weiny <ira.weiny@intel.com> > > > --- > > > drivers/cxl/core/pci.c | 2 ++ > > > drivers/pci/doe.c | 14 ++++++++++++-- > > > include/linux/pci-doe.h | 8 +++++--- > > > 3 files changed, 19 insertions(+), 5 deletions(-) > > > > > > diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c > > > index 9240df53ed87..a19c1fa0e2f4 100644 > > > --- a/drivers/cxl/core/pci.c > > > +++ b/drivers/cxl/core/pci.c > > > @@ -525,6 +525,7 @@ static int cxl_cdat_get_length(struct device *dev, > > > DECLARE_CDAT_DOE_TASK(CDAT_DOE_REQ(0), t); > > > int rc; > > > > > > + pci_doe_init_task(cdat_doe, &t.task, true); > > > rc = pci_doe_submit_task(cdat_doe, &t.task); > > > if (rc < 0) { > > > dev_err(dev, "DOE submit failed: %d", rc); > > > @@ -554,6 +555,7 @@ static int cxl_cdat_read_table(struct device *dev, > > > u32 *entry; > > > int rc; > > > > > > + pci_doe_init_task(cdat_doe, &t.task, true); > > > rc = pci_doe_submit_task(cdat_doe, &t.task); > > > if (rc < 0) { > > > dev_err(dev, "DOE submit failed: %d", rc); > > > diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c > > > index e402f05068a5..cabeae4ae955 100644 > > > --- a/drivers/pci/doe.c > > > +++ b/drivers/pci/doe.c > > > @@ -319,6 +319,7 @@ static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid, > > > }; > > > int rc; > > > > > > + pci_doe_init_task(doe_mb, &task, true); > > > rc = pci_doe_submit_task(doe_mb, &task); > > > if (rc < 0) > > > return rc; > > > @@ -495,6 +496,14 @@ bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type) > > > } > > > EXPORT_SYMBOL_GPL(pci_doe_supports_prot); > > > > > > +void pci_doe_init_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task, > > > + bool onstack) > > > +{ > > > + task->doe_mb = doe_mb; > > > + __INIT_WORK(&task->work, doe_statemachine_work, onstack); > > > +} > > > +EXPORT_SYMBOL_GPL(pci_doe_init_task); > > > + > > > /** > > > * pci_doe_submit_task() - Submit a task to be processed by the state machine > > > * > > > @@ -517,6 +526,9 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) > > > if (!pci_doe_supports_prot(doe_mb, task->prot.vid, task->prot.type)) > > > return -EINVAL; > > > > > > + if (WARN_ON_ONCE(task->work.func != doe_statemachine_work)) > > > + return -EINVAL; > > > + > > > /* > > > * DOE requests must be a whole number of DW and the response needs to > > > * be big enough for at least 1 DW > > > @@ -528,8 +540,6 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) > > > if (test_bit(PCI_DOE_FLAG_DEAD, &doe_mb->flags)) > > > return -EIO; > > > > > > - task->doe_mb = doe_mb; > > > - INIT_WORK(&task->work, doe_statemachine_work); > > > queue_work(doe_mb->work_queue, &task->work); > > > return 0; > > > } > > > diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h > > > index ed9b4df792b8..457fc0e53d64 100644 > > > --- a/include/linux/pci-doe.h > > > +++ b/include/linux/pci-doe.h > > > @@ -31,8 +31,8 @@ struct pci_doe_mb; > > > * @rv: Return value. Length of received response or error (bytes) > > > * @complete: Called when task is complete > > > * @private: Private data for the consumer > > > - * @work: Used internally by the mailbox > > > - * @doe_mb: Used internally by the mailbox > > > + * @work: Used internally by the mailbox [see pci_doe_init_task()] > > > + * @doe_mb: Used internally by the mailbox [see pci_doe_init_task()] > > > * > > > * The payload sizes and rv are specified in bytes with the following > > > * restrictions concerning the protocol. > > > @@ -53,7 +53,7 @@ struct pci_doe_task { > > > void (*complete)(struct pci_doe_task *task); > > > void *private; > > > > > > - /* No need for the user to initialize these fields */ > > > + /* Call pci_doe_init_task() for these */ > > > struct work_struct work; > > > struct pci_doe_mb *doe_mb; > > > }; > > > @@ -72,6 +72,8 @@ struct pci_doe_task { > > > > > > struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset); > > > bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type); > > > +void pci_doe_init_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task, > > > + bool onstack); > > > int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task); > > > > > > #endif > > > > > > base-commit: 30a0b95b1335e12efef89dd78518ed3e4a71a763 > > > -- > > > 2.37.2 > > >
On Tue, Nov 15, 2022 at 02:41:35PM -0600, Bjorn Helgaas wrote: > On Tue, Nov 15, 2022 at 12:18:38PM -0800, Ira Weiny wrote: > > On Tue, Nov 15, 2022 at 01:44:24PM -0600, Bjorn Helgaas wrote: > > > and say something more specific than "fix struct"? > > > > How about? > > > > PCI/DOE: Fix initialization of work struct in pci_doe_task > > The importance of this has to do with whether something is on the > stack, so I think something about that would be useful. > > I'm afraid this subject line bike-shedding has made you overlook my > other questions below ... Oh... I see now. > > > > On Mon, Nov 14, 2022 at 05:19:43PM -0800, ira.weiny@intel.com wrote: > > > > From: Ira Weiny <ira.weiny@intel.com> > > > > > > > > The callers of pci_doe_submit_task() allocate the pci_doe_task on the > > > > stack. This causes the work structure to be allocated on the stack > > > > without pci_doe_submit_task() knowing. Work item initialization needs > > > > to be done with either INIT_WORK_ONSTACK() or INIT_WORK() depending on > > > > how the work item is allocated. > > > > > > > > Jonathan suggested creating doe task allocation macros such as > > > > DECLARE_CDAT_DOE_TASK_ONSTACK().[1] The issue with this is the work > > > > function is not known to the callers and must be initialized correctly. > > > > > > > > A follow up suggestion was to have an internal 'pci_doe_work' item > > > > allocated by pci_doe_submit_task().[2] This requires an allocation which > > > > could restrict the context where tasks are used. > > > > > > > > Compromise with an intermediate step to initialize the task struct with > > > > a new call pci_doe_init_task() which must be called prior to submit > > > > task. > > > > > > I'm not really a fan of passing a parameter to say "this struct is on > > > the stack" because that seems kind of error-prone and I don't know > > > what the consequence of getting it wrong would be. Sounds like it > > > *could* be some memory corruption or reading garbage data that would > > > be hard to debug. > > > > > > Do we have cases today where pci_doe_submit_task() can't do the > > > kzalloc() as in your patch at [3]? No. > > > If the current use cases allow a > > > kzalloc(), why not do that now and defer this until it becomes an > > > issue? I do like pci_doe_submit_task() handling this as an internal detail. I'm happy with that if you are. I was just concerned about the restriction of context. Dan suggested this instead of passing a gfp parameter. If you are happy with my original patch I will submit it instead. (With a better one liner.) Thanks again for the review, Ira > > > > > > Bjorn > > > > > > > [1] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m88a7f50dcce52f30c8bf5c3dcc06fa9843b54a2d > > > > [2] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m63c636c5135f304480370924f4d03c00357be667 > > > > > > [3] https://lore.kernel.org/linux-cxl/Y2AnKB88ALYm9c5L@iweiny-desk3/ > > > > > > > Cc: Bjorn Helgaas <helgaas@kernel.org> > > > > Reported-by: Gregory Price <gregory.price@memverge.com> > > > > Reported-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > > > > Suggested-by: Dan Williams <dan.j.williams@intel.com> > > > > Signed-off-by: Ira Weiny <ira.weiny@intel.com> > > > > --- > > > > drivers/cxl/core/pci.c | 2 ++ > > > > drivers/pci/doe.c | 14 ++++++++++++-- > > > > include/linux/pci-doe.h | 8 +++++--- > > > > 3 files changed, 19 insertions(+), 5 deletions(-) > > > > > > > > diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c > > > > index 9240df53ed87..a19c1fa0e2f4 100644 > > > > --- a/drivers/cxl/core/pci.c > > > > +++ b/drivers/cxl/core/pci.c > > > > @@ -525,6 +525,7 @@ static int cxl_cdat_get_length(struct device *dev, > > > > DECLARE_CDAT_DOE_TASK(CDAT_DOE_REQ(0), t); > > > > int rc; > > > > > > > > + pci_doe_init_task(cdat_doe, &t.task, true); > > > > rc = pci_doe_submit_task(cdat_doe, &t.task); > > > > if (rc < 0) { > > > > dev_err(dev, "DOE submit failed: %d", rc); > > > > @@ -554,6 +555,7 @@ static int cxl_cdat_read_table(struct device *dev, > > > > u32 *entry; > > > > int rc; > > > > > > > > + pci_doe_init_task(cdat_doe, &t.task, true); > > > > rc = pci_doe_submit_task(cdat_doe, &t.task); > > > > if (rc < 0) { > > > > dev_err(dev, "DOE submit failed: %d", rc); > > > > diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c > > > > index e402f05068a5..cabeae4ae955 100644 > > > > --- a/drivers/pci/doe.c > > > > +++ b/drivers/pci/doe.c > > > > @@ -319,6 +319,7 @@ static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid, > > > > }; > > > > int rc; > > > > > > > > + pci_doe_init_task(doe_mb, &task, true); > > > > rc = pci_doe_submit_task(doe_mb, &task); > > > > if (rc < 0) > > > > return rc; > > > > @@ -495,6 +496,14 @@ bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type) > > > > } > > > > EXPORT_SYMBOL_GPL(pci_doe_supports_prot); > > > > > > > > +void pci_doe_init_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task, > > > > + bool onstack) > > > > +{ > > > > + task->doe_mb = doe_mb; > > > > + __INIT_WORK(&task->work, doe_statemachine_work, onstack); > > > > +} > > > > +EXPORT_SYMBOL_GPL(pci_doe_init_task); > > > > + > > > > /** > > > > * pci_doe_submit_task() - Submit a task to be processed by the state machine > > > > * > > > > @@ -517,6 +526,9 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) > > > > if (!pci_doe_supports_prot(doe_mb, task->prot.vid, task->prot.type)) > > > > return -EINVAL; > > > > > > > > + if (WARN_ON_ONCE(task->work.func != doe_statemachine_work)) > > > > + return -EINVAL; > > > > + > > > > /* > > > > * DOE requests must be a whole number of DW and the response needs to > > > > * be big enough for at least 1 DW > > > > @@ -528,8 +540,6 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) > > > > if (test_bit(PCI_DOE_FLAG_DEAD, &doe_mb->flags)) > > > > return -EIO; > > > > > > > > - task->doe_mb = doe_mb; > > > > - INIT_WORK(&task->work, doe_statemachine_work); > > > > queue_work(doe_mb->work_queue, &task->work); > > > > return 0; > > > > } > > > > diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h > > > > index ed9b4df792b8..457fc0e53d64 100644 > > > > --- a/include/linux/pci-doe.h > > > > +++ b/include/linux/pci-doe.h > > > > @@ -31,8 +31,8 @@ struct pci_doe_mb; > > > > * @rv: Return value. Length of received response or error (bytes) > > > > * @complete: Called when task is complete > > > > * @private: Private data for the consumer > > > > - * @work: Used internally by the mailbox > > > > - * @doe_mb: Used internally by the mailbox > > > > + * @work: Used internally by the mailbox [see pci_doe_init_task()] > > > > + * @doe_mb: Used internally by the mailbox [see pci_doe_init_task()] > > > > * > > > > * The payload sizes and rv are specified in bytes with the following > > > > * restrictions concerning the protocol. > > > > @@ -53,7 +53,7 @@ struct pci_doe_task { > > > > void (*complete)(struct pci_doe_task *task); > > > > void *private; > > > > > > > > - /* No need for the user to initialize these fields */ > > > > + /* Call pci_doe_init_task() for these */ > > > > struct work_struct work; > > > > struct pci_doe_mb *doe_mb; > > > > }; > > > > @@ -72,6 +72,8 @@ struct pci_doe_task { > > > > > > > > struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset); > > > > bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type); > > > > +void pci_doe_init_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task, > > > > + bool onstack); > > > > int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task); > > > > > > > > #endif > > > > > > > > base-commit: 30a0b95b1335e12efef89dd78518ed3e4a71a763 > > > > -- > > > > 2.37.2 > > > >
On Tue, Nov 15, 2022 at 12:54:39PM -0800, Ira Weiny wrote: > On Tue, Nov 15, 2022 at 02:41:35PM -0600, Bjorn Helgaas wrote: > > On Tue, Nov 15, 2022 at 12:18:38PM -0800, Ira Weiny wrote: > > > On Tue, Nov 15, 2022 at 01:44:24PM -0600, Bjorn Helgaas wrote: > > > > On Mon, Nov 14, 2022 at 05:19:43PM -0800, ira.weiny@intel.com wrote: > > > > > From: Ira Weiny <ira.weiny@intel.com> > > > > > > > > > > The callers of pci_doe_submit_task() allocate the > > > > > pci_doe_task on the stack. This causes the work structure > > > > > to be allocated on the stack without pci_doe_submit_task() > > > > > knowing. Work item initialization needs to be done with > > > > > either INIT_WORK_ONSTACK() or INIT_WORK() depending on how > > > > > the work item is allocated. > > > > > > > > > > Jonathan suggested creating doe task allocation macros such > > > > > as DECLARE_CDAT_DOE_TASK_ONSTACK().[1] The issue with this > > > > > is the work function is not known to the callers and must be > > > > > initialized correctly. > > > > > > > > > > A follow up suggestion was to have an internal > > > > > 'pci_doe_work' item allocated by pci_doe_submit_task().[2] > > > > > This requires an allocation which could restrict the context > > > > > where tasks are used. > > > > > > > > > > Compromise with an intermediate step to initialize the task > > > > > struct with a new call pci_doe_init_task() which must be > > > > > called prior to submit task. > > > > > > > > I'm not really a fan of passing a parameter to say "this struct is on > > > > the stack" because that seems kind of error-prone and I don't know > > > > what the consequence of getting it wrong would be. Sounds like it > > > > *could* be some memory corruption or reading garbage data that would > > > > be hard to debug. > > > > > > > > Do we have cases today where pci_doe_submit_task() can't do the > > > > kzalloc() as in your patch at [3]? > > No. > > > > > If the current use cases allow a > > > > kzalloc(), why not do that now and defer this until it becomes an > > > > issue? > > I do like pci_doe_submit_task() handling this as an internal detail. > I'm happy with that if you are. > > I was just concerned about the restriction of context. Dan > suggested this instead of passing a gfp parameter. > > If you are happy with my original patch I will submit it instead. > (With a better one liner.) I don't know what's coming as far as pci_doe_submit_task() callers. If there's some imminent caller that will require atomic context, I guess we could solve it now. But DOE doesn't really seem like an atomic context thing to begin with, so maybe we could postpone dealing with it. That patch in [3] is more complicated than I expected, but I admit I haven't looked closely. Bjorn > > > > > [1] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m88a7f50dcce52f30c8bf5c3dcc06fa9843b54a2d > > > > > [2] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m63c636c5135f304480370924f4d03c00357be667 > > > > > > > > [3] https://lore.kernel.org/linux-cxl/Y2AnKB88ALYm9c5L@iweiny-desk3/
On Mon, Nov 14, 2022 at 05:19:43PM -0800, ira.weiny@intel.com wrote: > From: Ira Weiny <ira.weiny@intel.com> > > The callers of pci_doe_submit_task() allocate the pci_doe_task on the > stack. This causes the work structure to be allocated on the stack > without pci_doe_submit_task() knowing. Work item initialization needs > to be done with either INIT_WORK_ONSTACK() or INIT_WORK() depending on > how the work item is allocated. > > Jonathan suggested creating doe task allocation macros such as > DECLARE_CDAT_DOE_TASK_ONSTACK().[1] The issue with this is the work > function is not known to the callers and must be initialized correctly. > > A follow up suggestion was to have an internal 'pci_doe_work' item > allocated by pci_doe_submit_task().[2] This requires an allocation which > could restrict the context where tasks are used. > > Compromise with an intermediate step to initialize the task struct with > a new call pci_doe_init_task() which must be called prior to submit > task. > > [1] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m88a7f50dcce52f30c8bf5c3dcc06fa9843b54a2d > [2] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m63c636c5135f304480370924f4d03c00357be667 We have object_is_on_stack(), included from <linux/sched/task_stack.h>. So you could just autosense in pci_doe_submit_task() whether pci_doe_task is on the stack and call the appropriate INIT_WORK variant. Any reason not to do that? Thanks, Lukas
On Wed, Nov 16, 2022 at 11:09:39AM +0100, Lukas Wunner wrote: > On Mon, Nov 14, 2022 at 05:19:43PM -0800, ira.weiny@intel.com wrote: > > From: Ira Weiny <ira.weiny@intel.com> > > > > The callers of pci_doe_submit_task() allocate the pci_doe_task on the > > stack. This causes the work structure to be allocated on the stack > > without pci_doe_submit_task() knowing. Work item initialization needs > > to be done with either INIT_WORK_ONSTACK() or INIT_WORK() depending on > > how the work item is allocated. > > > > Jonathan suggested creating doe task allocation macros such as > > DECLARE_CDAT_DOE_TASK_ONSTACK().[1] The issue with this is the work > > function is not known to the callers and must be initialized correctly. > > > > A follow up suggestion was to have an internal 'pci_doe_work' item > > allocated by pci_doe_submit_task().[2] This requires an allocation which > > could restrict the context where tasks are used. > > > > Compromise with an intermediate step to initialize the task struct with > > a new call pci_doe_init_task() which must be called prior to submit > > task. > > > > [1] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m88a7f50dcce52f30c8bf5c3dcc06fa9843b54a2d > > [2] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m63c636c5135f304480370924f4d03c00357be667 > > We have object_is_on_stack(), included from <linux/sched/task_stack.h>. > > So you could just autosense in pci_doe_submit_task() whether > pci_doe_task is on the stack and call the appropriate INIT_WORK > variant. Nifty, I had no idea object_is_on_stack() existed, thank you! I wonder if there's an opportunity to use object_is_on_stack() somewhere in the INIT_WORK() path to find usage mistakes. Adding it in pci_doe_submit_task() would add some complexity, so I'm not sure whether it's worth adding it unless we actually have uses for both cases. Bjorn
On Wed, Nov 16, 2022 at 12:20:37PM -0600, Bjorn Helgaas wrote: > On Wed, Nov 16, 2022 at 11:09:39AM +0100, Lukas Wunner wrote: > > On Mon, Nov 14, 2022 at 05:19:43PM -0800, ira.weiny@intel.com wrote: > > > From: Ira Weiny <ira.weiny@intel.com> > > > > > > The callers of pci_doe_submit_task() allocate the pci_doe_task on the > > > stack. This causes the work structure to be allocated on the stack > > > without pci_doe_submit_task() knowing. Work item initialization needs > > > to be done with either INIT_WORK_ONSTACK() or INIT_WORK() depending on > > > how the work item is allocated. > > > > > > Jonathan suggested creating doe task allocation macros such as > > > DECLARE_CDAT_DOE_TASK_ONSTACK().[1] The issue with this is the work > > > function is not known to the callers and must be initialized correctly. > > > > > > A follow up suggestion was to have an internal 'pci_doe_work' item > > > allocated by pci_doe_submit_task().[2] This requires an allocation which > > > could restrict the context where tasks are used. > > > > > > Compromise with an intermediate step to initialize the task struct with > > > a new call pci_doe_init_task() which must be called prior to submit > > > task. > > > > > > [1] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m88a7f50dcce52f30c8bf5c3dcc06fa9843b54a2d > > > [2] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m63c636c5135f304480370924f4d03c00357be667 > > > > We have object_is_on_stack(), included from <linux/sched/task_stack.h>. > > > > So you could just autosense in pci_doe_submit_task() whether > > pci_doe_task is on the stack and call the appropriate INIT_WORK > > variant. > > Nifty, I had no idea object_is_on_stack() existed, thank you! Indeed! Neither did I! thanks! > > I wonder if there's an opportunity to use object_is_on_stack() > somewhere in the INIT_WORK() path to find usage mistakes. I'm thinking we could make INIT_WORK do the right thing all the time. Not sure what the overhead of object_is_on_stack() is. > > Adding it in pci_doe_submit_task() would add some complexity, so I'm > not sure whether it's worth adding it unless we actually have uses for > both cases. I think if we don't do something we have to document that pci_doe_submit_task() only works with tasks on the stack. I would rather just make pci_doe_submit_task() correct and not complicate the callers. object_is_on_stack() can't be enough overhead to be worried about in this call path can it? Actually after writing all that I wonder if we can't push the use of object_is_on_stack() into the debug code? Something like below (completely untested)? I think this could be pushed even further down but I'd like to get opinions before attempting a change which will have a wider blast radius. Ira diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index a0143dd24430..4cc50b554a29 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -199,7 +199,7 @@ struct execute_work { struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, TIMER_DEFERRABLE) #ifdef CONFIG_DEBUG_OBJECTS_WORK -extern void __init_work(struct work_struct *work, int onstack); +extern void __init_work(struct work_struct *work); extern void destroy_work_on_stack(struct work_struct *work); extern void destroy_delayed_work_on_stack(struct delayed_work *work); static inline unsigned int work_static(struct work_struct *work) @@ -207,7 +207,7 @@ static inline unsigned int work_static(struct work_struct *work) return *work_data_bits(work) & WORK_STRUCT_STATIC; } #else -static inline void __init_work(struct work_struct *work, int onstack) { } +static inline void __init_work(struct work_struct *work) { } static inline void destroy_work_on_stack(struct work_struct *work) { } static inline void destroy_delayed_work_on_stack(struct delayed_work *work) { } static inline unsigned int work_static(struct work_struct *work) { return 0; } @@ -221,20 +221,20 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; } * to generate better code. */ #ifdef CONFIG_LOCKDEP -#define __INIT_WORK(_work, _func, _onstack) \ +#define __INIT_WORK(_work, _func) \ do { \ static struct lock_class_key __key; \ \ - __init_work((_work), _onstack); \ + __init_work(_work); \ (_work)->data = (atomic_long_t) WORK_DATA_INIT(); \ lockdep_init_map(&(_work)->lockdep_map, "(work_completion)"#_work, &__key, 0); \ INIT_LIST_HEAD(&(_work)->entry); \ (_work)->func = (_func); \ } while (0) #else -#define __INIT_WORK(_work, _func, _onstack) \ +#define __INIT_WORK(_work, _func) \ do { \ - __init_work((_work), _onstack); \ + __init_work(_work); \ (_work)->data = (atomic_long_t) WORK_DATA_INIT(); \ INIT_LIST_HEAD(&(_work)->entry); \ (_work)->func = (_func); \ @@ -242,10 +242,10 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; } #endif #define INIT_WORK(_work, _func) \ - __INIT_WORK((_work), (_func), 0) + __INIT_WORK((_work), (_func)) #define INIT_WORK_ONSTACK(_work, _func) \ - __INIT_WORK((_work), (_func), 1) + __INIT_WORK((_work), (_func)) #define __INIT_DELAYED_WORK(_work, _func, _tflags) \ do { \ diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 7cd5f5e7e0a1..7d87300cfbc6 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -515,9 +515,9 @@ static inline void debug_work_deactivate(struct work_struct *work) debug_object_deactivate(work, &work_debug_descr); } -void __init_work(struct work_struct *work, int onstack) +void __init_work(struct work_struct *work) { - if (onstack) + if (object_is_on_stack(work)) debug_object_init_on_stack(work, &work_debug_descr); else debug_object_init(work, &work_debug_descr);
Ira Weiny wrote: > On Wed, Nov 16, 2022 at 12:20:37PM -0600, Bjorn Helgaas wrote: > > On Wed, Nov 16, 2022 at 11:09:39AM +0100, Lukas Wunner wrote: > > > On Mon, Nov 14, 2022 at 05:19:43PM -0800, ira.weiny@intel.com wrote: > > > > From: Ira Weiny <ira.weiny@intel.com> > > > > > > > > The callers of pci_doe_submit_task() allocate the pci_doe_task on the > > > > stack. This causes the work structure to be allocated on the stack > > > > without pci_doe_submit_task() knowing. Work item initialization needs > > > > to be done with either INIT_WORK_ONSTACK() or INIT_WORK() depending on > > > > how the work item is allocated. > > > > > > > > Jonathan suggested creating doe task allocation macros such as > > > > DECLARE_CDAT_DOE_TASK_ONSTACK().[1] The issue with this is the work > > > > function is not known to the callers and must be initialized correctly. > > > > > > > > A follow up suggestion was to have an internal 'pci_doe_work' item > > > > allocated by pci_doe_submit_task().[2] This requires an allocation which > > > > could restrict the context where tasks are used. > > > > > > > > Compromise with an intermediate step to initialize the task struct with > > > > a new call pci_doe_init_task() which must be called prior to submit > > > > task. > > > > > > > > [1] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m88a7f50dcce52f30c8bf5c3dcc06fa9843b54a2d > > > > [2] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@huawei.com/T/#m63c636c5135f304480370924f4d03c00357be667 > > > > > > We have object_is_on_stack(), included from <linux/sched/task_stack.h>. > > > > > > So you could just autosense in pci_doe_submit_task() whether > > > pci_doe_task is on the stack and call the appropriate INIT_WORK > > > variant. > > > > Nifty, I had no idea object_is_on_stack() existed, thank you! > > Indeed! Neither did I! thanks! > > > > > I wonder if there's an opportunity to use object_is_on_stack() > > somewhere in the INIT_WORK() path to find usage mistakes. > > I'm thinking we could make INIT_WORK do the right thing all the time. Not sure > what the overhead of object_is_on_stack() is. > > > > > Adding it in pci_doe_submit_task() would add some complexity, so I'm > > not sure whether it's worth adding it unless we actually have uses for > > both cases. > > I think if we don't do something we have to document that > pci_doe_submit_task() only works with tasks on the stack. > > I would rather just make pci_doe_submit_task() correct and not complicate the > callers. object_is_on_stack() can't be enough overhead to be worried about in > this call path can it? > > Actually after writing all that I wonder if we can't push the use of > object_is_on_stack() into the debug code? Something like below (completely > untested)? I think this could be pushed even further down but I'd like to get > opinions before attempting a change which will have a wider blast radius. This looks reasonable, but I would do it after and independently of introducing the autosensing version of pci_doe_submit_task(). Then you can pursue this line of thinking and come back to simplify pci_doe_submit_task() if it indeed moves forward.
diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c index 9240df53ed87..a19c1fa0e2f4 100644 --- a/drivers/cxl/core/pci.c +++ b/drivers/cxl/core/pci.c @@ -525,6 +525,7 @@ static int cxl_cdat_get_length(struct device *dev, DECLARE_CDAT_DOE_TASK(CDAT_DOE_REQ(0), t); int rc; + pci_doe_init_task(cdat_doe, &t.task, true); rc = pci_doe_submit_task(cdat_doe, &t.task); if (rc < 0) { dev_err(dev, "DOE submit failed: %d", rc); @@ -554,6 +555,7 @@ static int cxl_cdat_read_table(struct device *dev, u32 *entry; int rc; + pci_doe_init_task(cdat_doe, &t.task, true); rc = pci_doe_submit_task(cdat_doe, &t.task); if (rc < 0) { dev_err(dev, "DOE submit failed: %d", rc); diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c index e402f05068a5..cabeae4ae955 100644 --- a/drivers/pci/doe.c +++ b/drivers/pci/doe.c @@ -319,6 +319,7 @@ static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid, }; int rc; + pci_doe_init_task(doe_mb, &task, true); rc = pci_doe_submit_task(doe_mb, &task); if (rc < 0) return rc; @@ -495,6 +496,14 @@ bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type) } EXPORT_SYMBOL_GPL(pci_doe_supports_prot); +void pci_doe_init_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task, + bool onstack) +{ + task->doe_mb = doe_mb; + __INIT_WORK(&task->work, doe_statemachine_work, onstack); +} +EXPORT_SYMBOL_GPL(pci_doe_init_task); + /** * pci_doe_submit_task() - Submit a task to be processed by the state machine * @@ -517,6 +526,9 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) if (!pci_doe_supports_prot(doe_mb, task->prot.vid, task->prot.type)) return -EINVAL; + if (WARN_ON_ONCE(task->work.func != doe_statemachine_work)) + return -EINVAL; + /* * DOE requests must be a whole number of DW and the response needs to * be big enough for at least 1 DW @@ -528,8 +540,6 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) if (test_bit(PCI_DOE_FLAG_DEAD, &doe_mb->flags)) return -EIO; - task->doe_mb = doe_mb; - INIT_WORK(&task->work, doe_statemachine_work); queue_work(doe_mb->work_queue, &task->work); return 0; } diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h index ed9b4df792b8..457fc0e53d64 100644 --- a/include/linux/pci-doe.h +++ b/include/linux/pci-doe.h @@ -31,8 +31,8 @@ struct pci_doe_mb; * @rv: Return value. Length of received response or error (bytes) * @complete: Called when task is complete * @private: Private data for the consumer - * @work: Used internally by the mailbox - * @doe_mb: Used internally by the mailbox + * @work: Used internally by the mailbox [see pci_doe_init_task()] + * @doe_mb: Used internally by the mailbox [see pci_doe_init_task()] * * The payload sizes and rv are specified in bytes with the following * restrictions concerning the protocol. @@ -53,7 +53,7 @@ struct pci_doe_task { void (*complete)(struct pci_doe_task *task); void *private; - /* No need for the user to initialize these fields */ + /* Call pci_doe_init_task() for these */ struct work_struct work; struct pci_doe_mb *doe_mb; }; @@ -72,6 +72,8 @@ struct pci_doe_task { struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset); bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type); +void pci_doe_init_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task, + bool onstack); int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task); #endif