Commit 1713dceb authored by Hans de Goede's avatar Hans de Goede Committed by Mauro Carvalho Chehab
Browse files

media: atomisp: fix -Wdangling-pointer warning 

ia_css_rmgr_acq_vbuf() uses a local on stack
"struct ia_css_rmgr_vbuf_handle v" variable.

When this path using this is hit, either the rmgr_pop_handle() call
will make *handle point to another vbuf-handle, or because
v.count == 0, ia_css_rmgr_refcount_retain_vbuf() will alloc a new
vbuf-handle and make *handle point to it.

So on leaving the function *handle will never point to the on stack
vbuf-handle, but gcc does not know this and emits the following:

drivers/staging/media/atomisp/pci/runtime/rmgr/src/rmgr_vbuf.c: In function ‘ia_css_rmgr_acq_vbuf’:
drivers/staging/media/atomisp/pci/runtime/rmgr/src/rmgr_vbuf.c:276:33: warning: storing the address of local variable ‘h’ in ‘*handle’ [-Wdangling-pointer=]
  276 |                         *handle = &h;
      |                         ~~~~~~~~^~~~
drivers/staging/media/atomisp/pci/runtime/rmgr/src/rmgr_vbuf.c:257:40: note: ‘h’ declared here
  257 |         struct ia_css_rmgr_vbuf_handle h;
      |                                        ^
drivers/staging/media/atomisp/pci/runtime/rmgr/src/rmgr_vbuf.c:257:40: note: ‘handle’ declared here

Rework the code using a new_handle helper to suppress this
false-postive compiler warning.

Link: https://lore.kernel.org/linux-media/20220612160556.108264-4-hdegoede@redhat.com


Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@kernel.org>
parent 42ec2f07

drivers/staging/media/atomisp/pci/runtime/rmgr/src/rmgr_vbuf.c

+15 −7
Original line number Diff line number Diff line
@@ -254,14 +254,15 @@ void rmgr_pop_handle(struct ia_css_rmgr_vbuf_pool *pool, 
void ia_css_rmgr_acq_vbuf(struct ia_css_rmgr_vbuf_pool *pool,

			  struct ia_css_rmgr_vbuf_handle **handle)

{

	struct ia_css_rmgr_vbuf_handle h = { 0 };



	if ((!pool) || (!handle) || (!*handle)) {

		IA_CSS_LOG("Invalid inputs");

		return;

	}



	if (pool->copy_on_write) {

		struct ia_css_rmgr_vbuf_handle *new_handle;

		struct ia_css_rmgr_vbuf_handle h = { 0 };



		/* only one reference, reuse (no new retain) */

		if ((*handle)->count == 1)

			return;
@@ -272,22 +273,29 @@ void ia_css_rmgr_acq_vbuf(struct ia_css_rmgr_vbuf_pool *pool, 
			h.size = (*handle)->size;

			/* release ref to current buffer */

			ia_css_rmgr_refcount_release_vbuf(handle);

			*handle = &h;

			new_handle = &h;

		} else {

			new_handle = *handle;

		}

		/* get new buffer for needed size */

		if ((*handle)->vptr == 0x0) {

		if (new_handle->vptr == 0x0) {

			if (pool->recycle) {

				/* try and pop from pool */

				rmgr_pop_handle(pool, handle);

				rmgr_pop_handle(pool, &new_handle);

			}

			if ((*handle)->vptr == 0x0) {

			if (new_handle->vptr == 0x0) {

				/* we need to allocate */

				(*handle)->vptr = hmm_alloc((*handle)->size);

				new_handle->vptr = hmm_alloc(new_handle->size);

			} else {

				/* we popped a buffer */

				*handle = new_handle;

				return;

			}

		}

		/* Note that new_handle will change to an internally maintained one */

		ia_css_rmgr_refcount_retain_vbuf(&new_handle);

		*handle = new_handle;

		return;

	}

	/* Note that handle will change to an internally maintained one */

	ia_css_rmgr_refcount_retain_vbuf(handle);