commit 3e9ca60a580e2b6854cd5314ebb0866a1f387ca8
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Thu Apr 8 07:39:32 2021 -0300

    linux: always update select timeout (BZ #27706)
    
    The timeout should be updated even on failure for time64 support.
    
    Checked on i686-linux-gnu.
    
    (cherry-pick from commit cedbf6d5f3f70ca911176de87d6e453eeab4b7a1)

diff --git a/misc/tst-select.c b/misc/tst-select.c
index 534105b50020fa44..52aa26651f612701 100644
--- a/misc/tst-select.c
+++ b/misc/tst-select.c
@@ -23,6 +23,7 @@
 #include <support/timespec.h>
 #include <support/xunistd.h>
 #include <support/xtime.h>
+#include <support/xsignal.h>
 
 struct child_args
 {
@@ -30,6 +31,12 @@ struct child_args
   struct timeval tmo;
 };
 
+static void
+alarm_handler (int signum)
+{
+  /* Do nothing.  */
+}
+
 static void
 do_test_child (void *clousure)
 {
@@ -59,6 +66,22 @@ do_test_child (void *clousure)
   xwrite (args->fds[1][1], "foo", 3);
 }
 
+static void
+do_test_child_alarm (void *clousure)
+{
+  struct sigaction act = { .sa_handler = alarm_handler };
+  xsigaction (SIGALRM, &act, NULL);
+  alarm (1);
+
+  struct timeval tv = { .tv_sec = 10, .tv_usec = 0 };
+  int r = select (0, NULL, NULL, NULL, &tv);
+  TEST_COMPARE (r, -1);
+  TEST_COMPARE (errno, EINTR);
+
+  if (support_select_modifies_timeout ())
+    TEST_VERIFY (tv.tv_sec < 10);
+}
+
 static int
 do_test (void)
 {
@@ -98,6 +121,13 @@ do_test (void)
   xclose (args.fds[0][0]);
   xclose (args.fds[1][1]);
 
+  {
+    struct support_capture_subprocess result;
+    result = support_capture_subprocess (do_test_child_alarm, NULL);
+    support_capture_subprocess_check (&result, "tst-select-child", 0,
+				      sc_allow_none);
+  }
+
   {
     fd_set rfds;
     FD_ZERO (&rfds);
diff --git a/sysdeps/unix/sysv/linux/select.c b/sysdeps/unix/sysv/linux/select.c
index 3b67ff44765ededf..dc16a816ed9e5f9b 100644
--- a/sysdeps/unix/sysv/linux/select.c
+++ b/sysdeps/unix/sysv/linux/select.c
@@ -107,7 +107,7 @@ __select64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
   r = SYSCALL_CANCEL (pselect6, nfds, readfds, writefds, exceptfds, pts32,
 		      NULL);
 # endif
-  if (r >= 0 && timeout != NULL)
+  if (timeout != NULL)
     *timeout = valid_timespec_to_timeval64 (ts32);
 #endif
 
@@ -128,7 +128,7 @@ __select (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
       ptv64 = &tv64;
     }
   int r = __select64 (nfds, readfds, writefds, exceptfds, ptv64);
-  if (r >= 0 && timeout != NULL)
+  if (timeout != NULL)
     /* The remanining timeout will be always less the input TIMEOUT.  */
     *timeout = valid_timeval64_to_timeval (tv64);
   return r;