gpu: nvgpu: Add synchronization to comptag alloc and clearing

Comptags allocation and clearing was not synchronized for a
buffer. Fix this race by serializing the operations with the
gk20a_dmabuf_priv lock. While doing that, add an error check in
the cbc_ctrl call.

Bug 1902982

Change-Id: Icd96f1855eb5e5340651bcc85849b5ccc199b821
Signed-off-by: Sami Kiminki <skiminki@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1597904
Reviewed-by: Alex Waterman <alexw@nvidia.com>
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 19 insertions, 1 deletions

diff --git a/drivers/gpu/nvgpu/include/nvgpu/comptags.h b/drivers/gpu/nvgpu/include/nvgpu/comptags.h
index 99e2d657..679a0f9e 100644
--- a/drivers/gpu/nvgpu/include/nvgpu/comptags.h
+++ b/drivers/gpu/nvgpu/include/nvgpu/comptags.h
@@ -74,6 +74,24 @@ int gk20a_alloc_or_get_comptags(struct gk20a *g,
                                 struct gk20a_comptags *comptags);
 void gk20a_get_comptags(struct nvgpu_os_buffer *buf,
                         struct gk20a_comptags *comptags);
-void gk20a_mark_comptags_cleared(struct nvgpu_os_buffer *buf);
+
+/*
+ * These functions must be used to synchronize comptags clear. The usage:
+ *
+ *   if (gk20a_comptags_start_clear(os_buf)) {
+ *           // we now hold the buffer lock for clearing
+ *
+ *           bool successful = hw_clear_comptags();
+ *
+ *           // mark the buf cleared (or not) and release the buffer lock
+ *           gk20a_comptags_finish_clear(os_buf, successful);
+ *   }
+ *
+ *  If gk20a_start_comptags_clear() returns false, another caller has
+ *  already cleared the comptags.
+ */
+bool gk20a_comptags_start_clear(struct nvgpu_os_buffer *buf);
+void gk20a_comptags_finish_clear(struct nvgpu_os_buffer *buf,
+                                 bool clear_successful);
 
 #endif