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https://sourceware.org/git/glibc.git
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linux: Only use 64-bit syscall if required for select
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. This also avoids the need to use supports_time64() (which breaks the usage case of live migration like CRIU or similar). It also fixes an issue on 32-bit select call for !__ASSUME_PSELECT (microblase with older kernels only) where the expected timeout is a 'struct timeval' instead of 'struct timespec'. 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>
This commit is contained in:
Adhemerval Zanella
parent
91cf411ad3
commit
4c3df0eba5
@ -21,6 +21,11 @@ extern int __pselect32 (int __nfds, fd_set *__readfds,
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const struct __timespec64 *__timeout,
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const __sigset_t *__sigmask)
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attribute_hidden;
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extern int __select32 (int __nfds, fd_set *__readfds,
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fd_set *__writefds, fd_set *__exceptfds,
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const struct __timespec64 *ts64,
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struct __timeval64 *timeout)
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attribute_hidden;
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extern int __select64 (int __nfds, fd_set *__readfds,
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fd_set *__writefds, fd_set *__exceptfds,
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@ -169,5 +169,7 @@ $(objpfx)tst-allocate_once-mem.out: $(objpfx)tst-allocate_once.out
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$(common-objpfx)malloc/mtrace $(objpfx)tst-allocate_once.mtrace > $@; \
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$(evaluate-test)
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$(objpfx)tst-select: $(librt)
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$(objpfx)tst-select-time64: $(librt)
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$(objpfx)tst-pselect: $(librt)
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$(objpfx)tst-pselect-time64: $(librt)
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@ -17,6 +17,7 @@
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<https://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <intprops.h>
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#include <support/capture_subprocess.h>
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#include <support/check.h>
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#include <support/support.h>
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@ -31,12 +32,6 @@ struct child_args
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struct timeval tmo;
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};
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static void
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alarm_handler (int signum)
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{
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/* Do nothing. */
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}
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static void
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do_test_child (void *clousure)
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{
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@ -69,17 +64,20 @@ do_test_child (void *clousure)
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static void
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do_test_child_alarm (void *clousure)
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{
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struct sigaction act = { .sa_handler = alarm_handler };
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xsigaction (SIGALRM, &act, NULL);
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alarm (1);
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struct child_args *args = (struct child_args *) clousure;
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struct timeval tv = { .tv_sec = 10, .tv_usec = 0 };
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support_create_timer (0, 100000000, false, NULL);
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struct timeval tv = { .tv_sec = args->tmo.tv_sec, .tv_usec = 0 };
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int r = select (0, NULL, NULL, NULL, &tv);
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TEST_COMPARE (r, -1);
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if (args->tmo.tv_sec > INT_MAX)
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TEST_VERIFY (errno == EINTR || errno == EOVERFLOW);
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else
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{
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TEST_COMPARE (errno, EINTR);
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if (support_select_modifies_timeout ())
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TEST_VERIFY (tv.tv_sec < 10);
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TEST_VERIFY (tv.tv_sec < args->tmo.tv_sec);
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}
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}
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static int
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@ -121,13 +119,24 @@ do_test (void)
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xclose (args.fds[0][0]);
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xclose (args.fds[1][1]);
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args.tmo = (struct timeval) { .tv_sec = 10, .tv_usec = 0 };
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{
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struct support_capture_subprocess result;
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result = support_capture_subprocess (do_test_child_alarm, NULL);
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result = support_capture_subprocess (do_test_child_alarm, &args);
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support_capture_subprocess_check (&result, "tst-select-child", 0,
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sc_allow_none);
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}
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args.tmo = (struct timeval) { .tv_sec = TYPE_MAXIMUM (time_t),
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.tv_usec = 0 };
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{
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struct support_capture_subprocess result;
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result = support_capture_subprocess (do_test_child_alarm, &args);
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support_capture_subprocess_check (&result, "tst-select-child", 0,
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sc_allow_none);
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}
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args.tmo = (struct timeval) { .tv_sec = 0, .tv_usec = 0 };
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{
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fd_set rfds;
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FD_ZERO (&rfds);
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@ -21,7 +21,6 @@
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#include <sys/select.h>
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#include <errno.h>
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#include <sysdep-cancel.h>
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#include <time64-support.h>
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/* Check the first NFDS descriptors each in READFDS (if not NULL) for read
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readiness, in WRITEFDS (if not NULL) for write readiness, and in EXCEPTFDS
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@ -65,53 +64,56 @@ __select64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
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#ifndef __NR_pselect6_time64
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# define __NR_pselect6_time64 __NR_pselect6
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#endif
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int r;
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if (supports_time64 ())
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{
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r = SYSCALL_CANCEL (pselect6_time64, nfds, readfds, writefds, exceptfds,
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#ifdef __ASSUME_TIME64_SYSCALLS
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int r = SYSCALL_CANCEL (pselect6_time64, nfds, readfds, writefds, exceptfds,
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pts64, NULL);
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/* Linux by default will update the timeout after a pselect6 syscall
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(though the pselect() glibc call suppresses this behavior).
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Since select() on Linux has the same behavior as the pselect6
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syscall, we update the timeout here. */
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if (r >= 0 || errno != ENOSYS)
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{
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if (timeout != NULL)
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TIMESPEC_TO_TIMEVAL (timeout, pts64);
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return r;
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#else
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bool need_time64 = timeout != NULL && !in_time_t_range (timeout->tv_sec);
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if (need_time64)
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{
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int r = SYSCALL_CANCEL (pselect6_time64, nfds, readfds, writefds,
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exceptfds, pts64, NULL);
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if ((r >= 0 || errno != ENOSYS) && timeout != NULL)
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{
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TIMESPEC_TO_TIMEVAL (timeout, &ts64);
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}
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else
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__set_errno (EOVERFLOW);
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return r;
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}
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mark_time64_unsupported ();
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}
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#ifndef __ASSUME_TIME64_SYSCALLS
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# ifdef __ASSUME_PSELECT
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struct timespec ts32, *pts32 = NULL;
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if (pts64 != NULL)
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{
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if (! in_time_t_range (pts64->tv_sec))
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{
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__set_errno (EINVAL);
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return -1;
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}
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ts32.tv_sec = s;
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ts32.tv_nsec = ns;
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ts32.tv_sec = pts64->tv_sec;
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ts32.tv_nsec = pts64->tv_nsec;
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pts32 = &ts32;
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}
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# ifndef __ASSUME_PSELECT
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# ifdef __NR__newselect
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# undef __NR_select
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# define __NR_select __NR__newselect
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# endif
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r = SYSCALL_CANCEL (select, nfds, readfds, writefds, exceptfds, pts32);
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# else
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r = SYSCALL_CANCEL (pselect6, nfds, readfds, writefds, exceptfds, pts32,
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NULL);
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# endif
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if (timeout != NULL)
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*timeout = valid_timespec_to_timeval64 (ts32);
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#endif
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int r = SYSCALL_CANCEL (pselect6, nfds, readfds, writefds, exceptfds, pts32,
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NULL);
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if (timeout != NULL)
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TIMESPEC_TO_TIMEVAL (timeout, pts32);
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return r;
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# else
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struct timeval tv32, *ptv32 = NULL;
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if (pts64 != NULL)
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{
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tv32 = valid_timespec64_to_timeval (*pts64);
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ptv32 = &tv32;
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}
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int r = SYSCALL_CANCEL (select, nfds, readfds, writefds, exceptfds, ptv32);
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if (timeout != NULL)
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*timeout = valid_timeval_to_timeval64 (tv32);
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return r;
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# endif /* __ASSUME_PSELECT */
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#endif
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}
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#if __TIMESIZE != 64
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