Fix compiling of example in io_uring.7 due to missing "errno" variable.

[huberteff]

The io_uring.7 manpage has an example that uses the "errno" variable.
This variable is not known and leads to a compiler error, due to a missing #include <errno.h>. Add it to get the example compiled.

Contact: Hubert Feyrer hubertf@gmx.de

=== BEFORE ===

$ gcc 4manpage-original.c -o 4manpage-original
4manpage-original.c: In function ‘io_uring_setup’: 4manpage-original.c:44:25: error: ‘errno’ undeclared (first use in this function)
44 | return (ret < 0) ? -errno : ret;
| ^~~~~
4manpage-original.c:15:1: note: ‘errno’ is defined in header ‘<errno.h>’; this is probably fixable by adding ‘#include <errno.h>’
14 | #include <linux/io_uring.h>
+++ |+#include <errno.h>
15 |
4manpage-original.c:44:25: note: each undeclared identifier is reported only once for each function it appears in
44 | return (ret < 0) ? -errno : ret;
| ^~~~~
4manpage-original.c: In function ‘io_uring_enter’:
4manpage-original.c:53:25: error: ‘errno’ undeclared (first use in this function)
53 | return (ret < 0) ? -errno : ret;
| ^~~~~
4manpage-original.c:53:25: note: ‘errno’ is defined in header ‘<errno.h>’; this is probably fixable by adding ‘#include <errno.h>’

==== PATCH ===

$ diff -u 4manpage-original.c 4manpage.c
--- 4manpage-original.c 2025-12-06 11:52:24.171027464 +0100 +++ 4manpage.c 2025-12-06 11:32:55.431256160 +0100 @@ -10,6 +10,7 @@
#include <unistd.h>
#include <string.h>
#include <stdatomic.h>
+#include <errno.h>

#include <linux/io_uring.h>

=== AFTER ===

$ gcc 4manpage.c -o 4manpage
$ cat 4manpage.c | ./4manpage | diff -u 4manpage.c - $

---

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src/queue: don't flush SQ ring for new wait interface

If we have IORING_FEAT_EXT_ARG, then timeouts are done through the
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Fixes: https://github.com/axboe/liburing/issues/402
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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[axboe]

Looks good to me, but your commit message is missing a Signed-off-by line, rather than that contact info line. Check other commits in the tree, if in doubt. It should go last in your commit message.

[huberteff]

Looks good to me, but your commit message is missing a Signed-off-by line, rather than that contact info line. Check other commits in the tree, if in doubt. It should go last in your commit message.

Done

[axboe]

@huberteff Sorry this still looks wrong. The correct tag is Signed-off-by, you have Sign-off-by in there. Can you do another amend and force push and I'll get this included?

[huberteff]

Sorry - next try...