about summary refs log tree commit diff
path: root/sysdeps
diff options
context:
space:
mode:
authorAdhemerval Zanella <adhemerval.zanella@linaro.org>2021-06-16 11:04:47 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2021-06-22 12:09:52 -0300
commitb769b0a2cbe469a42641e52f52484e18575b7f67 (patch)
treef1afdc9a400a92614f11044b4c46866cdd57a3c0 /sysdeps
parentb286eca5d4117b3e17c939e3df56e132ae623df1 (diff)
downloadglibc-b769b0a2cbe469a42641e52f52484e18575b7f67.tar.gz
glibc-b769b0a2cbe469a42641e52f52484e18575b7f67.tar.xz
glibc-b769b0a2cbe469a42641e52f52484e18575b7f67.zip
linux: Only use 64-bit syscall if required for internal futex
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>
Diffstat (limited to 'sysdeps')
-rw-r--r--sysdeps/nptl/futex-internal.h24
1 files changed, 16 insertions, 8 deletions
diff --git a/sysdeps/nptl/futex-internal.h b/sysdeps/nptl/futex-internal.h
index 969ab2bf4b..79a366604d 100644
--- a/sysdeps/nptl/futex-internal.h
+++ b/sysdeps/nptl/futex-internal.h
@@ -254,15 +254,23 @@ static __always_inline int
 futex_lock_pi64 (int *futex_word, const struct __timespec64 *abstime,
                  int private)
 {
-  int err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word,
-                                   __lll_private_flag
-                                   (FUTEX_LOCK_PI, private), 0, abstime);
-#ifndef __ASSUME_TIME64_SYSCALLS
-  if (err == -ENOSYS)
+  int err;
+#ifdef __ASSUME_TIME64_SYSCALLS
+  err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word,
+			       __lll_private_flag (FUTEX_LOCK_PI, private), 0,
+			       abstime);
+#else
+  bool need_time64 = abstime != NULL && !in_time_t_range (abstime->tv_sec);
+  if (need_time64)
+    {
+      err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word,
+				   __lll_private_flag (FUTEX_LOCK_PI, private),
+				   0, abstime);
+      if (err == -ENOSYS)
+	err = -EOVERFLOW;
+    }
+  else
     {
-      if (abstime != NULL && ! in_time_t_range (abstime->tv_sec))
-        return EOVERFLOW;
-
       struct timespec ts32;
       if (abstime != NULL)
         ts32 = valid_timespec64_to_timespec (*abstime);