gpu: nvgpu: Allow channel free to be forced

Allow forced channel freeing. This is useful when the driver is
being cleaned up and the gk20a_wait_until_counter_is_N() could
potentially hang.

Bug 1816516
Bug 1807277

Change-Id: I711f5f3f6413d0bb30b4857e785ca3b504b494ee
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: http://git-master/r/1250022
(cherry picked from commit e132d0e5ae77d758680ac708622a4883bbd69ba3)
Reviewed-on: http://git-master/r/1261918
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 20 insertions, 10 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
index c2a21b22..40766857 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
@@ -910,10 +910,8 @@ static void gk20a_wait_until_counter_is_N(
         }
 }
 
-
-
 /* call ONLY when no references to the channel exist: after the last put */
-static void gk20a_free_channel(struct channel_gk20a *ch)
+static void gk20a_free_channel(struct channel_gk20a *ch, bool force)
 {
         struct gk20a *g = ch->g;
         struct fifo_gk20a *f = &g->fifo;
@@ -935,9 +933,10 @@ static void gk20a_free_channel(struct channel_gk20a *ch)
         gk20a_disable_channel(ch);
 
         /* wait until there's only our ref to the channel */
-        gk20a_wait_until_counter_is_N(
-                ch, &ch->ref_count, 1, &ch->ref_count_dec_wq,
-                __func__, "references");
+        if (!force)
+                gk20a_wait_until_counter_is_N(
+                        ch, &ch->ref_count, 1, &ch->ref_count_dec_wq,
+                        __func__, "references");
 
         /* wait until all pending interrupts for recently completed
          * jobs are handled */
@@ -959,9 +958,10 @@ static void gk20a_free_channel(struct channel_gk20a *ch)
         atomic_dec(&ch->ref_count);
 
         /* wait until no more refs to the channel */
-        gk20a_wait_until_counter_is_N(
-                ch, &ch->ref_count, 0, &ch->ref_count_dec_wq,
-                __func__, "references");
+        if (!force)
+                gk20a_wait_until_counter_is_N(
+                        ch, &ch->ref_count, 0, &ch->ref_count_dec_wq,
+                        __func__, "references");
 
         /* if engine reset was deferred, perform it now */
         mutex_lock(&f->deferred_reset_mutex);
@@ -1132,7 +1132,17 @@ void _gk20a_channel_put(struct channel_gk20a *ch, const char *caller)
 
 void gk20a_channel_close(struct channel_gk20a *ch)
 {
-        gk20a_free_channel(ch);
+        gk20a_free_channel(ch, false);
+}
+
+/*
+ * Be careful with this - it is meant for terminating channels when we know the
+ * driver is otherwise dying. Ref counts and the like are ignored by this
+ * version of the cleanup.
+ */
+void __gk20a_channel_kill(struct channel_gk20a *ch)
+{
+        gk20a_free_channel(ch, true);
 }
 
 struct channel_gk20a *gk20a_get_channel_from_file(int fd)