On 4/24/23 08:33, Thomas Huth wrote:
On 20/04/2023 22.29, Cédric Le Goater wrote:
From: Cédric Le Goater <c...@redhat.com>
GCC13 reports an error :
../util/async.c: In function ‘aio_bh_poll’:
include/qemu/queue.h:303:22: error: storing the address of local variable
‘slice’ in ‘*ctx.bh_slice_list.sqh_last’ [-Werror=dangling-pointer=]
303 | (head)->sqh_last = &(elm)->field.sqe_next;
\
| ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
../util/async.c:169:5: note: in expansion of macro ‘QSIMPLEQ_INSERT_TAIL’
169 | QSIMPLEQ_INSERT_TAIL(&ctx->bh_slice_list, &slice, next);
| ^~~~~~~~~~~~~~~~~~~~
../util/async.c:161:17: note: ‘slice’ declared here
161 | BHListSlice slice;
| ^~~~~
../util/async.c:161:17: note: ‘ctx’ declared here
But the local variable 'slice' is removed from the global context list
in following loop of the same routine. Add a pragma to silent GCC.
Cc: Stefan Hajnoczi <stefa...@redhat.com>
Cc: Paolo Bonzini <pbonz...@redhat.com>
Cc: Daniel P. Berrangé <berra...@redhat.com>
Signed-off-by: Cédric Le Goater <c...@redhat.com>
---
util/async.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/util/async.c b/util/async.c
index 21016a1ac7..856e1a8a33 100644
--- a/util/async.c
+++ b/util/async.c
@@ -164,7 +164,21 @@ int aio_bh_poll(AioContext *ctx)
/* Synchronizes with QSLIST_INSERT_HEAD_ATOMIC in aio_bh_enqueue(). */
QSLIST_MOVE_ATOMIC(&slice.bh_list, &ctx->bh_list);
+
+ /*
+ * GCC13 [-Werror=dangling-pointer=] complains that the local variable
+ * 'slice' is being stored in the global 'ctx->bh_slice_list' but the
+ * list is emptied before this function returns.
+ */
+#if !defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wpragmas"
Why do we need to ignore -Wpragmas here?
To handle GCC 8.5 as suggested by Philippe :
https://lore.kernel.org/qemu-devel/24d45c41-2f62-76a2-4294-fcfa346c9...@linaro.org/
+#pragma GCC diagnostic ignored "-Wdangling-pointer="
+#endif
QSIMPLEQ_INSERT_TAIL(&ctx->bh_slice_list, &slice, next);
+#if !defined(__clang__)
+#pragma GCC diagnostic pop
+#endif
while ((s = QSIMPLEQ_FIRST(&ctx->bh_slice_list))) {
QEMUBH *bh;
Anyway:
Reviewed-by: Thomas Huth <th...@redhat.com>
Thanks,
C.
