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[FFmpeg-devel] libavutil/cpu: Fix definition of _GNU_SOURCE so it occurs before other includes

Message ID 1618226529-22995-1-git-send-email-kevin.j.wheatley@gmail.com
State New
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Series [FFmpeg-devel] libavutil/cpu: Fix definition of _GNU_SOURCE so it occurs before other includes
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Commit Message

Kevin Wheatley April 12, 2021, 11:22 a.m. UTC
From: Kevin Wheatley <kevin.j.wheatley@gmail.com>

This fix moves the potential definition of _GNU_SOURCE prior to
any includes of system header files as required by the documentation
https://www.gnu.org/software/libc/manual/html_node/Feature-Test-Macros.html

This corrects the CPU_COUNT macro availability, resulting in
sched_getaffinity() being called on Linux systems. This then correctly
returns the number of CPUs when run under containers and other cases
where processor affinity has been setup prior to running FFmpeg

Signed-off-by: Kevin J Wheatley <kevin.j.wheatley@gmail.com>
---
 libavutil/cpu.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

Comments

Kevin Wheatley April 26, 2021, 11:32 a.m. UTC | #1
On Mon, Apr 12, 2021 at 12:22 PM <kevin.j.wheatley@gmail.com> wrote:
>
> From: Kevin Wheatley <kevin.j.wheatley@gmail.com>
>
> This fix moves the potential definition of _GNU_SOURCE prior to
> any includes of system header files as required by the documentation
> https://www.gnu.org/software/libc/manual/html_node/Feature-Test-Macros.html
>
> This corrects the CPU_COUNT macro availability, resulting in
> sched_getaffinity() being called on Linux systems. This then correctly
> returns the number of CPUs when run under containers and other cases
> where processor affinity has been setup prior to running FFmpeg
>

bump

As an FYI the issue is triggered because the inclusion of the other
system headers prior to the _GNU_SOURCE definition results in the
CPU_COUNT macro not being defined, and so the affinity based CPU
counting fails to be used and so the cpu count is incorrectly
returned.

Kevin
diff mbox series

Patch

diff --git a/libavutil/cpu.c b/libavutil/cpu.c
index 8e3576a..1496c5d 100644
--- a/libavutil/cpu.c
+++ b/libavutil/cpu.c
@@ -16,6 +16,15 @@ 
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "config.h"
+
+#if HAVE_SCHED_GETAFFINITY
+#ifndef _GNU_SOURCE
+# define _GNU_SOURCE
+#endif
+#include <sched.h>
+#endif
+
 #include <stddef.h>
 #include <stdint.h>
 #include <stdatomic.h>
@@ -23,16 +32,9 @@ 
 #include "attributes.h"
 #include "cpu.h"
 #include "cpu_internal.h"
-#include "config.h"
 #include "opt.h"
 #include "common.h"
 
-#if HAVE_SCHED_GETAFFINITY
-#ifndef _GNU_SOURCE
-# define _GNU_SOURCE
-#endif
-#include <sched.h>
-#endif
 #if HAVE_GETPROCESSAFFINITYMASK || HAVE_WINRT
 #include <windows.h>
 #endif