[PATCH 5.16 022/285] drm/amdkfd: Dont take process mutex for svm ioctls

Greg Kroah-Hartman
2022-04-12T07:42:56Z

From: Philip Yang <Philip.Yang@amd.com>

[ Upstream commit ac7c48c0cce00d03b3c95fddcccb0a45257e33e3 ]

SVM ioctls take proper svms->lock to handle race conditions, don't need
take process mutex to serialize ioctls. This also fixes circular locking
warning:

WARNING: possible circular locking dependency detected

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock((work_completion)(&svms->deferred_list_work));
lock(&process->mutex);
lock((work_completion)(&svms->deferred_list_work));
lock(&process->mutex);

*** DEADLOCK ***

Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 4 ----
1 file changed, 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index 24ebd61395d8..3aaf10c778d7 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -1840,13 +1840,9 @@ static int kfd_ioctl_svm(struct file *filep, struct kfd_process *p, void *data)
if (!args->start_addr || !args->size)
return -EINVAL;

- mutex_lock(&p->mutex);
-
r = svm_ioctl(p, args->op, args->start_addr, args->size, args->nattr,
args->attrs);

- mutex_unlock(&p->mutex);
-
return r;
}
#else
--
2.35.1