From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Wed, 16 Jun 2021 12:50:53 +0000 (-0300)
Subject: linux: Only use 64-bit syscall if required for mq_timedsend
X-Git-Tag: glibc-2.34~247
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1faff2701163c76bad9bce76d644d13bce3e290a;p=thirdparty%2Fglibc.git

linux: Only use 64-bit syscall if required for mq_timedsend

For !__ASSUME_TIME64_SYSCALLS there is no need to issue a 64-bit syscall
if the provided timeout fits in a 32-bit one.  The 64-bit usage should
be rare since the timeout is a relative one.

Checked on i686-linux-gnu on a 4.15 kernel and on a 5.11 kernel
(with and without --enable-kernel=5.1) and on x86_64-linux-gnu.

Reviewed-by: Lukasz Majewski <lukma@denx.de>
---

diff --git a/rt/tst-mqueue10.c b/rt/tst-mqueue10.c
index 7fb53a1cae1..18795808e08 100644
--- a/rt/tst-mqueue10.c
+++ b/rt/tst-mqueue10.c
@@ -54,6 +54,16 @@ do_test (void)
     support_delete_timer (timer);
   }
 
+  {
+    timer_t timer = support_create_timer (0, 100000000, false, NULL);
+    /* Fill the internal buffer first.  */
+    TEST_COMPARE (mq_timedsend (q, msg, sizeof (msg), 0,
+				&(struct timespec) { 0, 0 }), 0);
+    TEST_COMPARE (mq_timedsend (q, msg, sizeof (msg), 0, &ts), -1);
+    TEST_VERIFY (errno == EINTR || errno == EOVERFLOW);
+    support_delete_timer (timer);
+  }
+
   mq_unlink (name);
 
   return 0;
diff --git a/sysdeps/unix/sysv/linux/mq_timedsend.c b/sysdeps/unix/sysv/linux/mq_timedsend.c
index 5f14ecb0bf9..d0835f005c7 100644
--- a/sysdeps/unix/sysv/linux/mq_timedsend.c
+++ b/sysdeps/unix/sysv/linux/mq_timedsend.c
@@ -29,30 +29,33 @@ __mq_timedsend_time64 (mqd_t mqdes, const char *msg_ptr, size_t msg_len,
 # ifndef __NR_mq_timedsend_time64
 #  define __NR_mq_timedsend_time64 __NR_mq_timedsend
 # endif
-  int ret = SYSCALL_CANCEL (mq_timedsend_time64, mqdes, msg_ptr, msg_len,
-			    msg_prio, abs_timeout);
 
-#ifndef __ASSUME_TIME64_SYSCALLS
-  if (ret == 0 || errno != ENOSYS)
-    return ret;
+#ifdef __ASSUME_TIME64_SYSCALLS
+  return SYSCALL_CANCEL (mq_timedsend_time64, mqdes, msg_ptr, msg_len,
+			 msg_prio, abs_timeout);
+#else
+  bool need_time64 = abs_timeout != NULL
+		     && !in_time_t_range (abs_timeout->tv_sec);
+  if (need_time64)
+    {
+      int r = SYSCALL_CANCEL (mq_timedsend_time64, mqdes, msg_ptr, msg_len,
+			      msg_prio, abs_timeout);
+      if (r == 0 || errno != ENOSYS)
+	return r;
+      __set_errno (EOVERFLOW);
+      return -1;
+    }
 
-  struct timespec ts32;
+  struct timespec ts32, *pts32 = NULL;
   if (abs_timeout != NULL)
     {
-      if (! in_time_t_range (abs_timeout->tv_sec))
-        {
-          __set_errno (EOVERFLOW);
-          return -1;
-        }
-
       ts32 = valid_timespec64_to_timespec (*abs_timeout);
+      pts32 = &ts32;
     }
 
-  ret = SYSCALL_CANCEL (mq_timedsend, mqdes, msg_ptr, msg_len, msg_prio,
-			abs_timeout != NULL ? &ts32 : NULL);
+  return SYSCALL_CANCEL (mq_timedsend, mqdes, msg_ptr, msg_len, msg_prio,
+			 pts32);
 #endif
-
-  return ret;
 }
 
 #if __TIMESIZE != 64