gpu: nvgpu: replace tsg list mutex with rwsem

Lock only for modifications to the tsg channel list, and allow multiple
concurrent readers.

Bug 1848834
Bug 1814773

Change-Id: Ie3938d4239cfe36a14211f4649ce72b7fc3e2fa4
Signed-off-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-on: http://git-master/r/1269579
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/vgpu/fifo_vgpu.c b/drivers/gpu/nvgpu/vgpu/fifo_vgpu.c
index c3669990..5ffc6a00 100644
--- a/drivers/gpu/nvgpu/vgpu/fifo_vgpu.c
+++ b/drivers/gpu/nvgpu/vgpu/fifo_vgpu.c
@@ -651,7 +651,7 @@ static int vgpu_fifo_force_reset_ch(struct channel_gk20a *ch,
         if (gk20a_is_channel_marked_as_tsg(ch)) {
                 tsg = &g->fifo.tsg[ch->tsgid];
 
-                mutex_lock(&tsg->ch_list_lock);
+                down_read(&tsg->ch_list_lock);
 
                 list_for_each_entry(ch_tsg, &tsg->ch_list, ch_entry) {
                         if (gk20a_channel_get(ch_tsg)) {
@@ -661,7 +661,7 @@ static int vgpu_fifo_force_reset_ch(struct channel_gk20a *ch,
                         }
                 }
 
-                mutex_unlock(&tsg->ch_list_lock);
+                up_read(&tsg->ch_list_lock);
         } else {
                 gk20a_set_error_notifier(ch, err_code);
                 ch->has_timedout = true;