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| author |   Daniel Marcovitch <dmarcovitch@nvidia.com> | 2023-06-09 10:51:45 +0000 |
|---|---|---|
| committer |   Joerg Roedel <jroedel@suse.de> | 2023-07-14 16:16:44 +0200 |
| commit | 534103bcd52ca9c1fecbc70e717b4a538dc4ded8 (patch) | |
| tree | b971314100b89400a82c540a31d56b8f5b710c5c | |
| parent | Linux 6.5-rc1 (diff) | |
| download | wireguard-linux-534103bcd52ca9c1fecbc70e717b4a538dc4ded8.tar.xz wireguard-linux-534103bcd52ca9c1fecbc70e717b4a538dc4ded8.zip | |
iommu/amd/iommu_v2: Fix pasid_state refcount dec hit 0 warning on pasid unbind
When unbinding pasid - a race condition exists vs outstanding page faults.
To prevent this, the pasid_state object contains a refcount.
* set to 1 on pasid bind
* incremented on each ppr notification start
* decremented on each ppr notification done
* decremented on pasid unbind
Since refcount_dec assumes that refcount will never reach 0:
the current implementation causes the following to be invoked on
pasid unbind:
REFCOUNT_WARN("decrement hit 0; leaking memory")
Fix this issue by changing refcount_dec to refcount_dec_and_test
to explicitly handle refcount=1.
Fixes: 8bc54824da4e ("iommu/amd: Convert from atomic_t to refcount_t on pasid_state->count")
Signed-off-by: Daniel Marcovitch <dmarcovitch@nvidia.com>
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/20230609105146.7773-2-vasant.hegde@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to '')
| -rw-r--r-- | drivers/iommu/amd/iommu_v2.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/iommu/amd/iommu_v2.c b/drivers/iommu/amd/iommu_v2.c index 261352a23271..65d78d7e0440 100644 --- a/drivers/iommu/amd/iommu_v2.c +++ b/drivers/iommu/amd/iommu_v2.c @@ -262,8 +262,8 @@ static void put_pasid_state(struct pasid_state *pasid_state) static void put_pasid_state_wait(struct pasid_state *pasid_state) { - refcount_dec(&pasid_state->count); - wait_event(pasid_state->wq, !refcount_read(&pasid_state->count)); + if (!refcount_dec_and_test(&pasid_state->count)) + wait_event(pasid_state->wq, !refcount_read(&pasid_state->count)); free_pasid_state(pasid_state); } |