gpu: nvgpu: protect channel ioctls with a mutex

Add a big mutex for protecting the channel during ioctls, in case the
userspace uses the same channel from several threads at once. The lock
is taken during all operations except CHANNEL_WAIT, which could deadlock.

Bug 1603482

Change-Id: Ibed962eadc9f00645abd54413dde9aaee00377ab
Signed-off-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-on: http://git-master/r/678871
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/channel_gk20a.h b/drivers/gpu/nvgpu/gk20a/channel_gk20a.h
index c028e3b1..034de53f 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_gk20a.h
+++ b/drivers/gpu/nvgpu/gk20a/channel_gk20a.h
@@ -1,7 +1,7 @@
 /*
  * GK20A graphics channel
  *
- * Copyright (c) 2011-2014, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2011-2015, NVIDIA CORPORATION.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -84,6 +84,7 @@ struct channel_gk20a {
         bool first_init;
         bool vpr;
         pid_t pid;
+        struct mutex ioctl_lock;
 
         int tsgid;
         struct list_head ch_entry; /* channel's entry in TSG */