172 lines
5.6 KiB
Diff
172 lines
5.6 KiB
Diff
commit 8380ca5833ef2a11bf0162f2290f4f8c85ce3b90
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Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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Date: Wed Mar 31 13:53:34 2021 -0300
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linux: Normalize and return timeout on select (BZ #27651)
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The commit 2433d39b697, which added time64 support to select, changed
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the function to use __NR_pselect6 (or __NR_pelect6_time64) on all
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architectures. However, on architectures where the symbol was
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implemented with __NR_select the kernel normalizes the passed timeout
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instead of return EINVAL. For instance, the input timeval
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{ 0, 5000000 } is interpreted as { 5, 0 }.
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And as indicated by BZ #27651, this semantic seems to be expected
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and changing it results in some performance issues (most likely
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the program does not check the return code and keeps issuing
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select with unormalized tv_usec argument).
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To avoid a different semantic depending whether which syscall the
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architecture used to issue, select now always normalize the timeout
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input. This is a slight change for some ABIs (for instance aarch64).
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Checked on x86_64-linux-gnu and i686-linux-gnu.
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(cherry picked from commit 9d7c5cc38e58fb0923e88901f87174a511b61552)
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diff --git a/include/time.h b/include/time.h
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index caf2af5e74ed6179..e0636132a6ee3fe9 100644
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--- a/include/time.h
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+++ b/include/time.h
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@@ -502,6 +502,11 @@ time_now (void)
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__clock_gettime (TIME_CLOCK_GETTIME_CLOCKID, &ts);
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return ts.tv_sec;
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}
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+
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+#define NSEC_PER_SEC 1000000000L /* Nanoseconds per second. */
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+#define USEC_PER_SEC 1000000L /* Microseconds per second. */
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+#define NSEC_PER_USEC 1000L /* Nanoseconds per microsecond. */
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+
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#endif
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#endif
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diff --git a/misc/tst-select.c b/misc/tst-select.c
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index 5ad057cd51d0f45c..534105b50020fa44 100644
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--- a/misc/tst-select.c
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+++ b/misc/tst-select.c
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@@ -19,6 +19,7 @@
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#include <errno.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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#include <support/timespec.h>
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#include <support/xunistd.h>
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#include <support/xtime.h>
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@@ -47,6 +48,12 @@ do_test_child (void *clousure)
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int r = select (args->fds[0][0] + 1, &rfds, NULL, NULL, &args->tmo);
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TEST_COMPARE (r, 0);
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+ if (support_select_modifies_timeout ())
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+ {
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+ TEST_COMPARE (args->tmo.tv_sec, 0);
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+ TEST_COMPARE (args->tmo.tv_usec, 0);
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+ }
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+
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TEST_TIMESPEC_NOW_OR_AFTER (CLOCK_REALTIME, ts);
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xwrite (args->fds[1][1], "foo", 3);
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@@ -69,6 +76,16 @@ do_test (void)
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sc_allow_none);
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}
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+ if (support_select_normalizes_timeout ())
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+ {
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+ /* This is handled as 1 second instead of failing with EINVAL. */
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+ args.tmo = (struct timeval) { .tv_sec = 0, .tv_usec = 1000000 };
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+ struct support_capture_subprocess result;
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+ result = support_capture_subprocess (do_test_child, &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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+
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/* Same as before, but simulating polling. */
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args.tmo = (struct timeval) { .tv_sec = 0, .tv_usec = 0 };
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{
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diff --git a/sunrpc/svcauth_des.c b/sunrpc/svcauth_des.c
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index 7607abc8186813f6..25a85c90970d4ced 100644
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--- a/sunrpc/svcauth_des.c
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+++ b/sunrpc/svcauth_des.c
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@@ -58,7 +58,6 @@
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#define debug(msg) /*printf("svcauth_des: %s\n", msg) */
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-#define USEC_PER_SEC ((uint32_t) 1000000L)
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#define BEFORE(t1, t2) timercmp(t1, t2, <)
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/*
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diff --git a/sysdeps/unix/sysv/linux/select.c b/sysdeps/unix/sysv/linux/select.c
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index 415aa87d3c87d70c..3b67ff44765ededf 100644
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--- a/sysdeps/unix/sysv/linux/select.c
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+++ b/sysdeps/unix/sysv/linux/select.c
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@@ -33,12 +33,34 @@ int
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__select64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
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struct __timeval64 *timeout)
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{
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- struct __timespec64 ts64, *pts64 = NULL;
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- if (timeout != NULL)
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+ __time64_t s = timeout != NULL ? timeout->tv_sec : 0;
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+ int32_t us = timeout != NULL ? timeout->tv_usec : 0;
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+ int32_t ns;
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+
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+ if (s < 0 || us < 0)
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+ return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
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+
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+ /* Normalize the timeout, as legacy Linux __NR_select and __NR__newselect.
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+ Different than syscall, it also handle possible overflow. */
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+ if (us / USEC_PER_SEC > INT64_MAX - s)
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{
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- ts64 = timeval64_to_timespec64 (*timeout);
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- pts64 = &ts64;
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+ s = INT64_MAX;
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+ ns = NSEC_PER_SEC - 1;
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}
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+ else
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+ {
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+ s += us / USEC_PER_SEC;
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+ us = us % USEC_PER_SEC;
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+ ns = us * NSEC_PER_USEC;
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+ }
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+
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+ struct __timespec64 ts64, *pts64 = NULL;
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+ if (timeout != NULL)
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+ {
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+ ts64.tv_sec = s;
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+ ts64.tv_nsec = ns;
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+ pts64 = &ts64;
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+ }
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#ifndef __NR_pselect6_time64
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# define __NR_pselect6_time64 __NR_pselect6
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@@ -52,10 +74,10 @@ __select64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
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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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+ if (r >= 0 || errno != ENOSYS)
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{
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if (timeout != NULL)
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- TIMEVAL_TO_TIMESPEC (timeout, &ts64);
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+ TIMESPEC_TO_TIMEVAL (timeout, &ts64);
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return r;
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}
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@@ -64,14 +86,15 @@ __select64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
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#ifndef __ASSUME_TIME64_SYSCALLS
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struct timespec ts32, *pts32 = NULL;
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- if (timeout != NULL)
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+ if (pts64 != NULL)
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{
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- if (! in_time_t_range (timeout->tv_sec))
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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 = valid_timespec64_to_timespec (ts64);
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+ ts32.tv_sec = s;
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+ ts32.tv_nsec = ns;
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pts32 = &ts32;
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}
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# ifndef __ASSUME_PSELECT
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