[12/18] linux: Only use 64-bit syscall if required for timerfd_settime
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Commit Message
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.
---
sysdeps/unix/sysv/linux/Makefile | 2 ++
sysdeps/unix/sysv/linux/timerfd_settime.c | 25 ++++++++++---------
sysdeps/unix/sysv/linux/tst-timerfd.c | 29 +++++++++++++++++++++--
3 files changed, 43 insertions(+), 13 deletions(-)
Comments
On Thu, 17 Jun 2021 08:50:58 -0300
Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote:
> 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.
> ---
> sysdeps/unix/sysv/linux/Makefile | 2 ++
> sysdeps/unix/sysv/linux/timerfd_settime.c | 25 ++++++++++---------
> sysdeps/unix/sysv/linux/tst-timerfd.c | 29
> +++++++++++++++++++++-- 3 files changed, 43 insertions(+), 13
> deletions(-)
>
> diff --git a/sysdeps/unix/sysv/linux/Makefile
> b/sysdeps/unix/sysv/linux/Makefile index 982755f980..2e5b5e1dc4 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -145,6 +145,8 @@ endif
>
> $(objpfx)tst-ppoll: $(librt)
> $(objpfx)tst-ppoll-time64: $(librt)
> +$(objpfx)tst-timerfd: $(librt)
> +$(objpfx)tst-timerfd-time64: $(librt)
>
> # Generate the list of SYS_* macros for the system calls (__NR_*
> # macros). The file syscall-names.list contains all possible system
> diff --git a/sysdeps/unix/sysv/linux/timerfd_settime.c
> b/sysdeps/unix/sysv/linux/timerfd_settime.c index
> 0dd6fa026e..8f08133a73 100644 ---
> a/sysdeps/unix/sysv/linux/timerfd_settime.c +++
> b/sysdeps/unix/sysv/linux/timerfd_settime.c @@ -29,31 +29,34 @@
> __timerfd_settime64 (int fd, int flags, const struct __itimerspec64
> *value, #ifndef __NR_timerfd_settime64 # define
> __NR_timerfd_settime64 __NR_timerfd_settime #endif
> - int ret = INLINE_SYSCALL_CALL (timerfd_settime64, fd, flags,
> value, ovalue); -#ifndef __ASSUME_TIME64_SYSCALLS
> - if (ret == 0 || errno != ENOSYS)
> - return ret;
>
> - if (! in_time_t_range ((value->it_value).tv_sec)
> - || ! in_time_t_range ((value->it_interval).tv_sec))
> +#ifdef __ASSUME_TIME64_SYSCALLS
> + return INLINE_SYSCALL_CALL (timerfd_settime64, fd, flags, value,
> ovalue); +#else
> + bool is32bit_value = in_time_t_range (value->it_value.tv_sec);
> + bool is32bit_interval = in_time_t_range
> (value->it_interval.tv_sec);
> + if (!is32bit_value || !is32bit_interval)
> {
> + int r = INLINE_SYSCALL_CALL (timerfd_settime64, fd, flags,
> value,
> + ovalue);
> + if (r == 0 || errno != ENOSYS)
> + return r;
> __set_errno (EOVERFLOW);
> - return -1;
> + return r;
> }
>
> struct itimerspec its32, oits32;
> its32.it_interval = valid_timespec64_to_timespec
> (value->it_interval); its32.it_value = valid_timespec64_to_timespec
> (value->it_value); -
> - ret = INLINE_SYSCALL_CALL (timerfd_settime, fd, flags,
> - &its32, ovalue ? &oits32 : NULL);
> + int ret = INLINE_SYSCALL_CALL (timerfd_settime, fd, flags,
> + &its32, ovalue != NULL ? &oits32 :
> NULL); if (ret == 0 && ovalue != NULL)
> {
> ovalue->it_interval = valid_timespec_to_timespec64
> (oits32.it_interval); ovalue->it_value = valid_timespec_to_timespec64
> (oits32.it_value); }
> -#endif
> return ret;
> +#endif
> }
>
> #if __TIMESIZE != 64
> diff --git a/sysdeps/unix/sysv/linux/tst-timerfd.c
> b/sysdeps/unix/sysv/linux/tst-timerfd.c index 8828399119..27f1263ac6
> 100644 --- a/sysdeps/unix/sysv/linux/tst-timerfd.c
> +++ b/sysdeps/unix/sysv/linux/tst-timerfd.c
> @@ -16,15 +16,18 @@
> License along with the GNU C Library; if not, see
> <https://www.gnu.org/licenses/>. */
>
> +#include <errno.h>
> +#include <intprops.h>
> #include <time.h>
> #include <support/check.h>
> +#include <support/support.h>
> #include <support/xunistd.h>
> #include <support/timespec.h>
> #include <sys/time.h>
> #include <sys/timerfd.h>
>
> -static int
> -do_test (void)
> +static void
> +timerfd_test (void)
> {
> struct itimerspec settings = { { 0, 0 }, { 2, 0 } };
> struct itimerspec val;
> @@ -52,6 +55,28 @@ do_test (void)
> /* Check difference between timerfd_gettime calls. */
> TEST_COMPARE (support_timespec_check_in_range
> ((struct timespec) { 1, 0 }, val.it_value, 0.9,
> 1.0), 1); +
> + xclose (fd);
> +}
> +
> +static void
> +timerfd_large_timeout (void)
> +{
> + int fd = timerfd_create (CLOCK_REALTIME, 0);
> + TEST_VERIFY (fd != -1);
> + support_create_timer (0, 100000000, false, NULL);
> + struct itimerspec it = { { 0, 0 }, { TYPE_MAXIMUM (time_t), 0 } };
> + TEST_COMPARE (timerfd_settime (fd, 0, &it, NULL), 0);
> + uint64_t buf;
> + TEST_COMPARE (read (fd, &buf, sizeof (buf)), -1);
> + TEST_VERIFY (errno == EINTR || errno == EOVERFLOW);
> +}
> +
> +static int
> +do_test (void)
> +{
> + timerfd_test ();
> + timerfd_large_timeout ();
> return 0;
> }
>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Best regards,
Lukasz Majewski
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de
@@ -145,6 +145,8 @@ endif
$(objpfx)tst-ppoll: $(librt)
$(objpfx)tst-ppoll-time64: $(librt)
+$(objpfx)tst-timerfd: $(librt)
+$(objpfx)tst-timerfd-time64: $(librt)
# Generate the list of SYS_* macros for the system calls (__NR_*
# macros). The file syscall-names.list contains all possible system
@@ -29,31 +29,34 @@ __timerfd_settime64 (int fd, int flags, const struct __itimerspec64 *value,
#ifndef __NR_timerfd_settime64
# define __NR_timerfd_settime64 __NR_timerfd_settime
#endif
- int ret = INLINE_SYSCALL_CALL (timerfd_settime64, fd, flags, value, ovalue);
-#ifndef __ASSUME_TIME64_SYSCALLS
- if (ret == 0 || errno != ENOSYS)
- return ret;
- if (! in_time_t_range ((value->it_value).tv_sec)
- || ! in_time_t_range ((value->it_interval).tv_sec))
+#ifdef __ASSUME_TIME64_SYSCALLS
+ return INLINE_SYSCALL_CALL (timerfd_settime64, fd, flags, value, ovalue);
+#else
+ bool is32bit_value = in_time_t_range (value->it_value.tv_sec);
+ bool is32bit_interval = in_time_t_range (value->it_interval.tv_sec);
+ if (!is32bit_value || !is32bit_interval)
{
+ int r = INLINE_SYSCALL_CALL (timerfd_settime64, fd, flags, value,
+ ovalue);
+ if (r == 0 || errno != ENOSYS)
+ return r;
__set_errno (EOVERFLOW);
- return -1;
+ return r;
}
struct itimerspec its32, oits32;
its32.it_interval = valid_timespec64_to_timespec (value->it_interval);
its32.it_value = valid_timespec64_to_timespec (value->it_value);
-
- ret = INLINE_SYSCALL_CALL (timerfd_settime, fd, flags,
- &its32, ovalue ? &oits32 : NULL);
+ int ret = INLINE_SYSCALL_CALL (timerfd_settime, fd, flags,
+ &its32, ovalue != NULL ? &oits32 : NULL);
if (ret == 0 && ovalue != NULL)
{
ovalue->it_interval = valid_timespec_to_timespec64 (oits32.it_interval);
ovalue->it_value = valid_timespec_to_timespec64 (oits32.it_value);
}
-#endif
return ret;
+#endif
}
#if __TIMESIZE != 64
@@ -16,15 +16,18 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
+#include <errno.h>
+#include <intprops.h>
#include <time.h>
#include <support/check.h>
+#include <support/support.h>
#include <support/xunistd.h>
#include <support/timespec.h>
#include <sys/time.h>
#include <sys/timerfd.h>
-static int
-do_test (void)
+static void
+timerfd_test (void)
{
struct itimerspec settings = { { 0, 0 }, { 2, 0 } };
struct itimerspec val;
@@ -52,6 +55,28 @@ do_test (void)
/* Check difference between timerfd_gettime calls. */
TEST_COMPARE (support_timespec_check_in_range
((struct timespec) { 1, 0 }, val.it_value, 0.9, 1.0), 1);
+
+ xclose (fd);
+}
+
+static void
+timerfd_large_timeout (void)
+{
+ int fd = timerfd_create (CLOCK_REALTIME, 0);
+ TEST_VERIFY (fd != -1);
+ support_create_timer (0, 100000000, false, NULL);
+ struct itimerspec it = { { 0, 0 }, { TYPE_MAXIMUM (time_t), 0 } };
+ TEST_COMPARE (timerfd_settime (fd, 0, &it, NULL), 0);
+ uint64_t buf;
+ TEST_COMPARE (read (fd, &buf, sizeof (buf)), -1);
+ TEST_VERIFY (errno == EINTR || errno == EOVERFLOW);
+}
+
+static int
+do_test (void)
+{
+ timerfd_test ();
+ timerfd_large_timeout ();
return 0;
}