gpu: nvgpu: Add nvgpu_mem_is_valid() call

Add a function to check if an nvgpu_mem is allocated (valid) or not.
Also fix possibly leaked state in nvgpu_mems when they fail to
allocate.

Also ensure that in the case of a failure to allocate no state is
accidentally leaked to the caller. This should hopefully make it
less likely that a caller thinks a buffer that failed to allocate
is actually allocated.

Change-Id: I43224ece7da84e63b2f43f36f04941126fabf3c7
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1559419
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
Reviewed-by: svccoveritychecker <svccoveritychecker@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 19 insertions, 1 deletions

diff --git a/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h b/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h
index f3be65c2..a112623e 100644
--- a/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h
+++ b/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h
@@ -39,7 +39,7 @@ struct nvgpu_gmmu_attrs;
  * memory actually was allocated from.
  */
 enum nvgpu_aperture {
-        APERTURE_INVALID, /* unallocated or N/A */
+        APERTURE_INVALID = 0, /* unallocated or N/A */
         APERTURE_SYSMEM,
         APERTURE_VIDMEM
 };
@@ -122,6 +122,24 @@ static inline const char *nvgpu_aperture_str(enum nvgpu_aperture aperture)
         return "UNKNOWN";
 }
 
+/*
+ * Returns true if the passed nvgpu_mem has been allocated (i.e it's valid for
+ * subsequent use).
+ */
+static inline bool nvgpu_mem_is_valid(struct nvgpu_mem *mem)
+{
+        /*
+         * Internally the DMA APIs must set/unset the aperture flag when
+         * allocating/freeing the buffer. So check that to see if the *mem
+         * has been allocated or not.
+         *
+         * This relies on mem_descs being zeroed before being initialized since
+         * APERTURE_INVALID is equal to 0.
+         */
+        return mem->aperture != APERTURE_INVALID;
+
+}
+
 /**
  * nvgpu_mem_create_from_mem - Create a new nvgpu_mem struct from an old one.
  *