2 files changed, 18 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
index f554cf77..f48ef35f 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
@@ -682,8 +682,11 @@ void gk20a_free_channel(struct channel_gk20a *ch, bool finish)
         else
                 gk20a_vm_put(ch_vm);
 
+        spin_lock(&ch->update_fn_lock);
         ch->update_fn = NULL;
         ch->update_fn_data = NULL;
+        spin_unlock(&ch->update_fn_lock);
+        cancel_work_sync(&ch->update_fn_work);
 
 unbind:
         if (gk20a_is_channel_marked_as_tsg(ch))
@@ -745,7 +748,16 @@ static void gk20a_channel_update_runcb_fn(struct work_struct *work)
 {
         struct channel_gk20a *ch =
                 container_of(work, struct channel_gk20a, update_fn_work);
-        ch->update_fn(ch, ch->update_fn_data);
+        void (*update_fn)(struct channel_gk20a *, void *);
+        void *update_fn_data;
+
+        spin_lock(&ch->update_fn_lock);
+        update_fn = ch->update_fn;
+        update_fn_data = ch->update_fn_data;
+        spin_unlock(&ch->update_fn_lock);
+
+        if (update_fn)
+                update_fn(ch, update_fn_data);
 }
 
 struct channel_gk20a *gk20a_open_new_channel_with_cb(struct gk20a *g,
@@ -755,8 +767,10 @@ struct channel_gk20a *gk20a_open_new_channel_with_cb(struct gk20a *g,
         struct channel_gk20a *ch = gk20a_open_new_channel(g);
 
         if (ch) {
+                spin_lock(&ch->update_fn_lock);
                 ch->update_fn = update_fn;
                 ch->update_fn_data = update_fn_data;
+                spin_unlock(&ch->update_fn_lock);
         }
 
         return ch;
@@ -811,7 +825,7 @@ struct channel_gk20a *gk20a_open_new_channel(struct gk20a *g)
 
         ch->update_fn = NULL;
         ch->update_fn_data = NULL;
-
+        spin_lock_init(&ch->update_fn_lock);
         INIT_WORK(&ch->update_fn_work, gk20a_channel_update_runcb_fn);
 
         return ch;
diff --git a/drivers/gpu/nvgpu/gk20a/channel_gk20a.h b/drivers/gpu/nvgpu/gk20a/channel_gk20a.h
index a028b6f3..263ca291 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_gk20a.h
+++ b/drivers/gpu/nvgpu/gk20a/channel_gk20a.h
@@ -24,6 +24,7 @@
 #include <linux/mutex.h>
 #include <uapi/linux/nvgpu.h>
 #include <linux/poll.h>
+#include <linux/spinlock.h>
 
 struct gk20a;
 struct gr_gk20a;
@@ -162,6 +163,7 @@ struct channel_gk20a {
          * via schedule_work */
         void (*update_fn)(struct channel_gk20a *, void *);
         void *update_fn_data;
+        spinlock_t update_fn_lock; /* make access to the two above atomic */
         struct work_struct update_fn_work;
 };