gpu: nvgpu: acquire mutex for notifier read

We use &ch->error_notifier_mutex to protect
writes and free of error notifier
But we currently do not protect reading of
notifier in gk20a_fifo_set_ctx_mmu_error()
and vgpu_fifo_set_ctx_mmu_error()

Add new API gk20a_set_error_notifier_locked()
which is same as gk20a_set_error_notifier()
but without the locks.

In *_fifo_set_ctx_mmu_error() APIs, acquire
the mutex explicitly, and then use this new
API

gk20a_set_error_notifier() will now just call
gk20a_set_error_notifier_locked() within
a mutex

Bug 1824788
Bug 1844312

Change-Id: I1f3831dc63fe1daa761b2e17e4de3c155f505d6f
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/1273471
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Richard Zhao <rizhao@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/vgpu/fifo_vgpu.c b/drivers/gpu/nvgpu/vgpu/fifo_vgpu.c
index 5ffc6a00..e9a2d582 100644
--- a/drivers/gpu/nvgpu/vgpu/fifo_vgpu.c
+++ b/drivers/gpu/nvgpu/vgpu/fifo_vgpu.c
@@ -678,17 +678,20 @@ static int vgpu_fifo_force_reset_ch(struct channel_gk20a *ch,
 static void vgpu_fifo_set_ctx_mmu_error(struct gk20a *g,
                 struct channel_gk20a *ch)
 {
-        if (ch->error_notifier) {
+        mutex_lock(&ch->error_notifier_mutex);
+        if (ch->error_notifier_ref) {
                 if (ch->error_notifier->status == 0xffff) {
                         /* If error code is already set, this mmu fault
                          * was triggered as part of recovery from other
                          * error condition.
                          * Don't overwrite error flag. */
                 } else {
-                        gk20a_set_error_notifier(ch,
+                        gk20a_set_error_notifier_locked(ch,
                                 NVGPU_CHANNEL_FIFO_ERROR_MMU_ERR_FLT);
                 }
         }
+        mutex_unlock(&ch->error_notifier_mutex);
+
         /* mark channel as faulted */
         ch->has_timedout = true;
         wmb();