gpu: nvgpu: Misc fixes for crashes on shutdown

Fix miscellaneous issues seen during driver shutdown.

 o  Make sure pointers are valid before accessing them.
 o  Busy the GPU during channel timeout.
 o  Cancel delayed work on channels.
 o  Avoid access to channels that may have been freed.

Bug 1816516
Bug 1807277

Change-Id: I62df40373fdfb1c4a011364e8c435176a08a7a96
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: http://git-master/r/1250026
(cherry picked from commit 64a95fc96c8ef7c5af9c53c4bb3402626e0d2f60)
Reviewed-on: http://git-master/r/1274474
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
index 15170820..7b5013ea 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
@@ -1038,6 +1038,8 @@ static void gk20a_free_channel(struct channel_gk20a *ch, bool force)
         ch->update_fn_data = NULL;
         spin_unlock(&ch->update_fn_lock);
         cancel_work_sync(&ch->update_fn_work);
+        cancel_delayed_work_sync(&ch->clean_up.wq);
+        cancel_delayed_work_sync(&ch->timeout.wq);
 
         /* make sure we don't have deferred interrupts pending that
          * could still touch the channel */
@@ -1177,8 +1179,7 @@ int gk20a_channel_release(struct inode *inode, struct file *filp)
 
         err = gk20a_busy(g->dev);
         if (err) {
-                gk20a_err(dev_from_gk20a(g), "failed to release channel %d",
-                        ch->hw_chid);
+                gk20a_err(dev_from_gk20a(g), "failed to release a channel!");
                 return err;
         }
 
@@ -2108,6 +2109,11 @@ static void gk20a_channel_timeout_handler(struct work_struct *work)
 
         g = ch->g;
 
+        if (gk20a_busy(dev_from_gk20a(g))) {
+                gk20a_channel_put(ch);
+                return;
+        }
+
         /* Need global lock since multiple channels can timeout at a time */
         mutex_lock(&g->ch_wdt_lock);
 
@@ -2139,6 +2145,7 @@ static void gk20a_channel_timeout_handler(struct work_struct *work)
 fail_unlock:
         mutex_unlock(&g->ch_wdt_lock);
         gk20a_channel_put(ch);
+        gk20a_idle(dev_from_gk20a(g));
 }
 
 int gk20a_free_priv_cmdbuf(struct channel_gk20a *c, struct priv_cmd_entry *e)