| Message ID | 1443794485-30565-1-git-send-email-clombard@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
Acked-by: Ian Munsie <imunsie@au1.ibm.com> Excerpts from Christophe Lombard's message of 2015-10-03 00:01:25 +1000: > This moves the initialisation of the num_procs to before the SPA > allocation. > > Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com> > --- > drivers/misc/cxl/native.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c > index b37f2e8..d2e75c8 100644 > --- a/drivers/misc/cxl/native.c > +++ b/drivers/misc/cxl/native.c > @@ -457,6 +457,7 @@ static int activate_afu_directed(struct cxl_afu *afu) > > dev_info(&afu->dev, "Activating AFU directed mode\n"); > > + afu->num_procs = afu->max_procs_virtualised; > if (afu->spa == NULL) { > if (cxl_alloc_spa(afu)) > return -ENOMEM; > @@ -468,7 +469,6 @@ static int activate_afu_directed(struct cxl_afu *afu) > cxl_p1n_write(afu, CXL_PSL_ID_An, CXL_PSL_ID_An_F | CXL_PSL_ID_An_L); > > afu->current_mode = CXL_MODE_DIRECTED; > - afu->num_procs = afu->max_procs_virtualised; > > if ((rc = cxl_chardev_m_afu_add(afu))) > return rc;
On Fri, 2015-10-02 at 16:01 +0200, Christophe Lombard wrote: > This moves the initialisation of the num_procs to before the SPA > allocation. Why? What does it fix? I can't tell from the diff or the change log. cheers
The field 'num_procs' of the structure cxl_afu is not updated to the right value (maximum number of processes that can be supported by the AFU) when the pages are allocated (i.e. when cxl_alloc_spa() is called). The number of allocates pages depends on the max number of processes. Thanks On 06/10/2015 08:19, Michael Ellerman wrote: > On Fri, 2015-10-02 at 16:01 +0200, Christophe Lombard wrote: >> This moves the initialisation of the num_procs to before the SPA >> allocation. > Why? What does it fix? I can't tell from the diff or the change log. > > cheers > > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev
Excerpts from Michael Ellerman's message of 2015-10-06 17:19:02 +1100: > On Fri, 2015-10-02 at 16:01 +0200, Christophe Lombard wrote: > > This moves the initialisation of the num_procs to before the SPA > > allocation. > > Why? What does it fix? I can't tell from the diff or the change log. This will mean we only ever allocate a fixed number of pages for the scheduled process area (which in itself looks like it has a minor bug as it will start trying at two pages instead of one), which will limit us to 958 processes with 2 x 64K pages. If we actually try to use more processes than that we'd probably overrun the buffer and corrupt memory or crash. The only reason we haven't hit this out in the field so far is any AFUs the requires at least three interrupts per process is already limited to less processes than that anyway (e.g. min of 4 interrupts limits it to 509 processes, and all the AFUs I'm aware of require at least that many interrupts), but we could hit it on an AFU that requires 0, 1 or 2 interrupts per process, or when using 4K pages. This fix should go to stable. @Christophe, can you resend with this info in the commit message? Cheers, -Ian
diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c index b37f2e8..d2e75c8 100644 --- a/drivers/misc/cxl/native.c +++ b/drivers/misc/cxl/native.c @@ -457,6 +457,7 @@ static int activate_afu_directed(struct cxl_afu *afu) dev_info(&afu->dev, "Activating AFU directed mode\n"); + afu->num_procs = afu->max_procs_virtualised; if (afu->spa == NULL) { if (cxl_alloc_spa(afu)) return -ENOMEM; @@ -468,7 +469,6 @@ static int activate_afu_directed(struct cxl_afu *afu) cxl_p1n_write(afu, CXL_PSL_ID_An, CXL_PSL_ID_An_F | CXL_PSL_ID_An_L); afu->current_mode = CXL_MODE_DIRECTED; - afu->num_procs = afu->max_procs_virtualised; if ((rc = cxl_chardev_m_afu_add(afu))) return rc;
This moves the initialisation of the num_procs to before the SPA allocation. Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com> --- drivers/misc/cxl/native.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)