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| author | Oded Gabbay <oded.gabbay@amd.com> | 2014-11-10 11:21:39 +0100 |
|---|---|---|
| committer | Joerg Roedel <jroedel@suse.de> | 2014-11-12 14:58:33 +0100 |
| commit | 1c51099a427dc8bfee917b2d0e53ad3fafbb930d (patch) | |
| tree | a53eb05b225c532e1e0b6da9b2db6c5e15cafafb | |
| parent | Linux 3.18-rc4 (diff) | |
| download | linux-1c51099a427dc8bfee917b2d0e53ad3fafbb930d.tar.xz linux-1c51099a427dc8bfee917b2d0e53ad3fafbb930d.zip | |
iommu/amd: Fix accounting of device_state
This patch fixes a bug in the accounting of the
device_state. In the current code, the device_state was put
(decremented) too many times, which sometimes lead to the
driver getting stuck permanently in put_device_state_wait().
That happen because the device_state->count would go below
zero, which is never supposed to happen.
The root cause is that the device_state was decremented in
put_pasid_state() and put_pasid_state_wait() but also in all
the functions that call those functions. Therefore, the
device_state was decremented twice in each of these code
paths.
The fix is to decouple the device_state accounting from the
pasid_state accounting - remove the call to
put_device_state() from the put_pasid_state() and the
put_pasid_state_wait())
Signed-off-by: Oded Gabbay <oded.gabbay@amd.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
| -rw-r--r-- | drivers/iommu/amd_iommu_v2.c | 8 |
1 files changed, 2 insertions, 6 deletions
diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c index 90d734bbf467..a2d87a60c27f 100644 --- a/drivers/iommu/amd_iommu_v2.c +++ b/drivers/iommu/amd_iommu_v2.c @@ -279,10 +279,8 @@ static void free_pasid_state(struct pasid_state *pasid_state) static void put_pasid_state(struct pasid_state *pasid_state) { - if (atomic_dec_and_test(&pasid_state->count)) { - put_device_state(pasid_state->device_state); + if (atomic_dec_and_test(&pasid_state->count)) wake_up(&pasid_state->wq); - } } static void put_pasid_state_wait(struct pasid_state *pasid_state) @@ -291,9 +289,7 @@ static void put_pasid_state_wait(struct pasid_state *pasid_state) prepare_to_wait(&pasid_state->wq, &wait, TASK_UNINTERRUPTIBLE); - if (atomic_dec_and_test(&pasid_state->count)) - put_device_state(pasid_state->device_state); - else + if (!atomic_dec_and_test(&pasid_state->count)) schedule(); finish_wait(&pasid_state->wq, &wait); |