| Message ID | 20211126232734.708730446@linutronix.de |
|---|---|
| State | New |
| Headers | show |
| Series | genirq/msi, PCI/MSI: Spring cleaning - Part 2 | expand |
On Sat, Nov 27, 2021 at 02:22:38AM +0100, Thomas Gleixner wrote: > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> No changelog? Anyway, why do we care about the number of decriptors? > --- > include/linux/msi.h | 3 +++ > kernel/irq/msi.c | 18 ++++++++++++++++++ > 2 files changed, 21 insertions(+) > > --- a/include/linux/msi.h > +++ b/include/linux/msi.h > @@ -156,6 +156,7 @@ enum msi_desc_filter { > * msi_device_data - MSI per device data > * @lock: Spinlock to protect register access > * @properties: MSI properties which are interesting to drivers > + * @num_descs: The number of allocated MSI descriptors for the device > * @attrs: Pointer to the sysfs attribute group > * @platform_data: Platform-MSI specific data > * @list: List of MSI descriptors associated to the device > @@ -166,6 +167,7 @@ enum msi_desc_filter { > struct msi_device_data { > raw_spinlock_t lock; > unsigned long properties; > + unsigned int num_descs; > const struct attribute_group **attrs; > struct platform_msi_priv_data *platform_data; > struct list_head list; > @@ -208,6 +210,7 @@ static inline unsigned int msi_get_virq( > > void msi_lock_descs(struct device *dev); > void msi_unlock_descs(struct device *dev); > +unsigned int msi_device_num_descs(struct device *dev); > > struct msi_desc *__msi_first_desc(struct device *dev, enum msi_desc_filter filter, unsigned int base_index); > struct msi_desc *msi_next_desc(struct device *dev); > --- a/kernel/irq/msi.c > +++ b/kernel/irq/msi.c > @@ -82,6 +82,7 @@ int msi_add_msi_desc(struct device *dev, > desc->pci = init_desc->pci; > > list_add_tail(&desc->list, &dev->msi.data->list); > + dev->msi.data->num_descs++; > return 0; > } > > @@ -109,6 +110,7 @@ int msi_add_simple_msi_descs(struct devi > list_add_tail(&desc->list, &list); > } > list_splice_tail(&list, &dev->msi.data->list); > + dev->msi.data->num_descs += ndesc; > return 0; > > fail: > @@ -142,6 +144,7 @@ void msi_free_msi_descs_range(struct dev > continue; > list_del(&desc->list); > free_msi_entry(desc); > + dev->msi.data->num_descs--; > } > } > > @@ -157,6 +160,21 @@ bool msi_device_has_property(struct devi > return !!(dev->msi.data->properties & prop); > } > > +/** > + * msi_device_num_descs - Query the number of allocated MSI descriptors of a device > + * @dev: The device to read from > + * > + * Note: This is a lockless snapshot of msi_device_data::num_descs > + * > + * Returns the number of MSI descriptors which are allocated for @dev > + */ > +unsigned int msi_device_num_descs(struct device *dev) > +{ > + if (dev->msi.data) > + return dev->msi.data->num_descs; As this number can change after it is read, what will callers do with it? thanks, greg k-h
On Sat, Nov 27 2021 at 13:19, Greg Kroah-Hartman wrote: > On Sat, Nov 27, 2021 at 02:22:38AM +0100, Thomas Gleixner wrote: >> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > > No changelog? Bah. This one should not be there at all. > Anyway, why do we care about the number of decriptors? >> +/** >> + * msi_device_num_descs - Query the number of allocated MSI descriptors of a device >> + * @dev: The device to read from >> + * >> + * Note: This is a lockless snapshot of msi_device_data::num_descs >> + * >> + * Returns the number of MSI descriptors which are allocated for @dev >> + */ >> +unsigned int msi_device_num_descs(struct device *dev) >> +{ >> + if (dev->msi.data) >> + return dev->msi.data->num_descs; > > As this number can change after it is read, what will callers do with > it? I wanted to get rid of this, but then forgot. Getting old. Thanks, tglx
On Sat, Nov 27 2021 at 20:22, Thomas Gleixner wrote: > On Sat, Nov 27 2021 at 13:19, Greg Kroah-Hartman wrote: >> On Sat, Nov 27, 2021 at 02:22:38AM +0100, Thomas Gleixner wrote: >>> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> >> >> No changelog? > > Bah. This one should not be there at all. > >> Anyway, why do we care about the number of decriptors? The last part of this really cares about it for the dynamic extension part, but that's core code which looks at the counter under the lock. Thanks, tglx
On Sat, Nov 27, 2021 at 08:45:18PM +0100, Thomas Gleixner wrote: > On Sat, Nov 27 2021 at 20:22, Thomas Gleixner wrote: > > > On Sat, Nov 27 2021 at 13:19, Greg Kroah-Hartman wrote: > >> On Sat, Nov 27, 2021 at 02:22:38AM +0100, Thomas Gleixner wrote: > >>> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > >> > >> No changelog? > > > > Bah. This one should not be there at all. > > > >> Anyway, why do we care about the number of decriptors? > > The last part of this really cares about it for the dynamic extension > part, but that's core code which looks at the counter under the lock. Ah, that should be documented well as right now you are saying "this is done lockless" in the comment :) thanks, greg k-h
On Sun, Nov 28 2021 at 12:07, Greg Kroah-Hartman wrote: > On Sat, Nov 27, 2021 at 08:45:18PM +0100, Thomas Gleixner wrote: >> On Sat, Nov 27 2021 at 20:22, Thomas Gleixner wrote: >> >> > On Sat, Nov 27 2021 at 13:19, Greg Kroah-Hartman wrote: >> >> On Sat, Nov 27, 2021 at 02:22:38AM +0100, Thomas Gleixner wrote: >> >>> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> >> >> >> >> No changelog? >> > >> > Bah. This one should not be there at all. >> > >> >> Anyway, why do we care about the number of decriptors? >> >> The last part of this really cares about it for the dynamic extension >> part, but that's core code which looks at the counter under the lock. > > Ah, that should be documented well as right now you are saying "this is > done lockless" in the comment :) I already zapped the whole patch as the function is not required for the core code. Thanks, tglx
--- a/include/linux/msi.h +++ b/include/linux/msi.h @@ -156,6 +156,7 @@ enum msi_desc_filter { * msi_device_data - MSI per device data * @lock: Spinlock to protect register access * @properties: MSI properties which are interesting to drivers + * @num_descs: The number of allocated MSI descriptors for the device * @attrs: Pointer to the sysfs attribute group * @platform_data: Platform-MSI specific data * @list: List of MSI descriptors associated to the device @@ -166,6 +167,7 @@ enum msi_desc_filter { struct msi_device_data { raw_spinlock_t lock; unsigned long properties; + unsigned int num_descs; const struct attribute_group **attrs; struct platform_msi_priv_data *platform_data; struct list_head list; @@ -208,6 +210,7 @@ static inline unsigned int msi_get_virq( void msi_lock_descs(struct device *dev); void msi_unlock_descs(struct device *dev); +unsigned int msi_device_num_descs(struct device *dev); struct msi_desc *__msi_first_desc(struct device *dev, enum msi_desc_filter filter, unsigned int base_index); struct msi_desc *msi_next_desc(struct device *dev); --- a/kernel/irq/msi.c +++ b/kernel/irq/msi.c @@ -82,6 +82,7 @@ int msi_add_msi_desc(struct device *dev, desc->pci = init_desc->pci; list_add_tail(&desc->list, &dev->msi.data->list); + dev->msi.data->num_descs++; return 0; } @@ -109,6 +110,7 @@ int msi_add_simple_msi_descs(struct devi list_add_tail(&desc->list, &list); } list_splice_tail(&list, &dev->msi.data->list); + dev->msi.data->num_descs += ndesc; return 0; fail: @@ -142,6 +144,7 @@ void msi_free_msi_descs_range(struct dev continue; list_del(&desc->list); free_msi_entry(desc); + dev->msi.data->num_descs--; } } @@ -157,6 +160,21 @@ bool msi_device_has_property(struct devi return !!(dev->msi.data->properties & prop); } +/** + * msi_device_num_descs - Query the number of allocated MSI descriptors of a device + * @dev: The device to read from + * + * Note: This is a lockless snapshot of msi_device_data::num_descs + * + * Returns the number of MSI descriptors which are allocated for @dev + */ +unsigned int msi_device_num_descs(struct device *dev) +{ + if (dev->msi.data) + return dev->msi.data->num_descs; + return 0; +} + void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg) { *msg = entry->msg;
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- include/linux/msi.h | 3 +++ kernel/irq/msi.c | 18 ++++++++++++++++++ 2 files changed, 21 insertions(+)