gpu: nvgpu: serialize debug session IOCTLs

Hold debug_s->ioctl_lock for all debug session
IOCTLs to prevent multi-threaded user space
IOCTL calls

debug session IOCTL calls are not thread-safe
and hence this serialization is required

Bug 1832267

Change-Id: I847ac951601d4f0093546b592bdb8c8f00185317
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/1286436
Reviewed-by: svccoveritychecker <svccoveritychecker@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/dbg_gpu_gk20a.c b/drivers/gpu/nvgpu/gk20a/dbg_gpu_gk20a.c
index be9f7fc6..ac11e378 100644
--- a/drivers/gpu/nvgpu/gk20a/dbg_gpu_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/dbg_gpu_gk20a.c
@@ -1,7 +1,7 @@
 /*
  * Tegra GK20A GPU Debugger/Profiler Driver
  *
- * Copyright (c) 2013-2016, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2013-2017, 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,
@@ -117,6 +117,7 @@ static int gk20a_dbg_gpu_do_dev_open(struct inode *inode,
         init_waitqueue_head(&dbg_session->dbg_events.wait_queue);
         INIT_LIST_HEAD(&dbg_session->ch_list);
         mutex_init(&dbg_session->ch_list_lock);
+        mutex_init(&dbg_session->ioctl_lock);
         dbg_session->dbg_events.events_enabled = false;
         dbg_session->dbg_events.num_pending_events = 0;
 
@@ -899,6 +900,9 @@ long gk20a_dbg_gpu_dev_ioctl(struct file *filp, unsigned int cmd,
                 gk20a_idle(g->dev);
         }
 
+        /* protect from threaded user space calls */
+        mutex_lock(&dbg_s->ioctl_lock);
+
         switch (cmd) {
         case NVGPU_DBG_GPU_IOCTL_BIND_CHANNEL:
                 err = dbg_bind_channel_gk20a(dbg_s,
@@ -1003,6 +1007,8 @@ long gk20a_dbg_gpu_dev_ioctl(struct file *filp, unsigned int cmd,
                 break;
         }
 
+        mutex_unlock(&dbg_s->ioctl_lock);
+
         gk20a_dbg(gpu_dbg_gpu_dbg, "ret=%d", err);
 
         if ((err == 0) && (_IOC_DIR(cmd) & _IOC_READ))