video: tegra: host: Fix race in sync dump

The code assumed that the sync framework will not call nvhost
specific functions until the pointer has been returned to
the caller. In most cases this is a fair assumption, however,
if the sync dump was in progress at the same time we created a
new fence, we may try to print out fence specific data before
it has been created.

This function adds necessary check to nvhost_sync_pt_value_str()
which is the only function suffering from this issue.

Bug 200001909

Change-Id: Ieaf8352eb48aedbb984e05caec241aca3e593810
Signed-off-by: Arto Merilainen <amerilainen@nvidia.com>
Reviewed-on: http://git-master/r/407592
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

diff --git a/drivers/video/tegra/host/nvhost_sync.c b/drivers/video/tegra/host/nvhost_sync.c
index 4bb4bd58be669188cb51e4ff305c4bbf9d9bdf5e..66688defc8fdb7406e26c6d637c10417715f3f98 100644 (file)
--- a/drivers/video/tegra/host/nvhost_sync.c
+++ b/drivers/video/tegra/host/nvhost_sync.c
@@ -220,7 +220,13 @@ static void nvhost_sync_pt_value_str(struct sync_pt *sync_pt, char *str,
                int size)
 {
        struct nvhost_sync_pt *pt = to_nvhost_sync_pt(sync_pt);
-       struct nvhost_sync_timeline *obj = pt->obj;
+       struct nvhost_sync_timeline *obj;
+
+       /* shared data may not be available yet */
+       if (!pt)
+               return;
+
+       obj = pt->obj;
 
        if (obj->id != NVSYNCPT_INVALID)
                snprintf(str, size, "%d", pt->thresh);