Commit d4b52cf2 authored May 29, 2023 by Konrad Sztyber Committed by Tomasz Zawadzki May 31, 2023

include: suppress Wdangling-pointer warnings in queue_extras.h



Newer versions of gcc (13) are reporting bogus warnings when doing a
TAILQ_SWAP() with a tailq declared on stack.  For example:

In file included from /src/spdk-2/include/spdk/queue.h:22,
                 from /src/spdk-2/include/spdk/dma.h:14,
                 from /src/spdk-2/include/spdk/accel.h:15,
                 from /src/spdk-2/include/spdk/accel_module.h:12,
                 from accel.c:9:
accel.c: In function ‘spdk_accel_sequence_reverse’:
/src/spdk-2/include/spdk/queue_extras.h:344:27: error: storing the address of local variable ‘tasks’ in ‘*seq.tasks.tqh_last’ [-Werror=dangling-pointer=]
  344 |         (head2)->tqh_last = swap_last;                                  \
      |         ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~
accel.c:1926:9: note: in expansion of macro ‘TAILQ_SWAP’
 1926 |         TAILQ_SWAP(&tasks, &seq->tasks, spdk_accel_task, seq_link);
      |         ^~~~~~~~~~
accel.c:1922:37: note: ‘tasks’ declared here
 1922 |         struct accel_sequence_tasks tasks = TAILQ_HEAD_INITIALIZER(tasks);
      |                                     ^~~~~

The address of a local variable is indeed stored in tqh_last, but a few
lines later it is overwritten (tqh_first is NULL in this case, because
it's initialized by TAILQ_HEAD_INITIALIZER):

if ((swap_first = (head2)->tqh_first) != NULL)			\
	swap_first->field.tqe_prev = &(head2)->tqh_first;	\
else								\
	(head2)->tqh_last = &(head2)->tqh_first;		\

So, suppress those warnings if using gcc-13 and up.

Fixes #3030.

Signed-off-by: Konrad Sztyber <konrad.sztyber@intel.com>
Change-Id: I0c6d68bcfef29b345f968832ba62114e5a639ffa
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/18439


Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Community-CI: Mellanox Build Bot
Reviewed-by: Kamil Godzwon <kamilx.godzwon@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>

parent a214d48d

include/spdk/queue_extras.h

+14 −0

Original line number	Diff line number	Diff line
		@@ -106,6 +106,18 @@
		*
		*/

		/* gcc-13 reports bogus Wdangling-pointer warnings on some of the macros below (see issue #3030) */
		#if defined(__GNUC__) && (__GNUC__ >= 13)
		#define SPDK_QE_SUPPRESS_WARNINGS() do { \
		_Pragma("GCC diagnostic push") \
		_Pragma("GCC diagnostic ignored \"-Wdangling-pointer\"") \
		} while (0)
		#define SPDK_QE_UNSUPPRESS_WARNINGS() _Pragma("GCC diagnostic pop")
		#else
		#define SPDK_QE_SUPPRESS_WARNINGS()
		#define SPDK_QE_UNSUPPRESS_WARNINGS()
		#endif

		/*
		* Singly-linked Tail queue declarations.
		*/
		@@ -323,6 +335,7 @@ struct { \
		((((struct headname )((elm)->field.tqe_prev))->tqh_last))

		#define TAILQ_SWAP(head1, head2, type, field) do { \
		SPDK_QE_SUPPRESS_WARNINGS(); \
		struct type *swap_first = (head1)->tqh_first; \
		struct type **swap_last = (head1)->tqh_last; \
		(head1)->tqh_first = (head2)->tqh_first; \
		@@ -337,6 +350,7 @@ struct { \
		swap_first->field.tqe_prev = &(head2)->tqh_first; \
		else \
		(head2)->tqh_last = &(head2)->tqh_first; \
		SPDK_QE_UNSUPPRESS_WARNINGS(); \
		} while (0)

		#endif