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genirq/affinity: Create affinity mask for single vector

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Since commit c66d4bd110 ("genirq/affinity: Add new callback for
(re)calculating interrupt sets"), irq_create_affinity_masks() returns
NULL in case of single vector. This change has caused regression on some
drivers, such as lpfc.

The problem is that single vector requests can happen in some generic cases:

  1) kdump kernel

  2) irq vectors resource is close to exhaustion.

If in that situation the affinity mask for a single vector is not created,
every caller has to handle the special case.

There is no reason why the mask cannot be created, so remove the check for
a single vector and create the mask.

Fixes: c66d4bd110 ("genirq/affinity: Add new callback for (re)calculating interrupt sets")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190805011906.5020-1-ming.lei@redhat.com
This commit is contained in:
Ming Lei 2019-08-05 09:19:06 +08:00 committed by Thomas Gleixner
parent 33920f1ec5
commit 491beed3b1
1 changed files with 2 additions and 4 deletions
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6
kernel/irq/affinity.c
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@ -251,11 +251,9 @@ irq_create_affinity_masks(unsigned int nvecs, struct irq_affinity *affd)
* Determine the number of vectors which need interrupt affinities
* assigned. If the pre/post request exhausts the available vectors
* then nothing to do here except for invoking the calc_sets()
* callback so the device driver can adjust to the situation. If there
* is only a single vector, then managing the queue is pointless as
* well.
* callback so the device driver can adjust to the situation.
*/
if (nvecs > 1 && nvecs > affd->pre_vectors + affd->post_vectors)
if (nvecs > affd->pre_vectors + affd->post_vectors)
affvecs = nvecs - affd->pre_vectors - affd->post_vectors;
else
affvecs = 0;