From 4c3df0eba5e8fe98f0de917ade9b2ebba6951c5f Mon Sep 17 00:00:00 2001
From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Tue, 15 Jun 2021 21:00:50 -0300
Subject: 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>
---
 misc/Makefile     |  2 ++
 misc/tst-select.c | 39 ++++++++++++++++++++++++---------------
 2 files changed, 26 insertions(+), 15 deletions(-)

(limited to 'misc')

diff --git a/misc/Makefile b/misc/Makefile
index fa40bf0..66586bc 100644
--- a/misc/Makefile
+++ b/misc/Makefile
@@ -169,5 +169,7 @@ $(objpfx)tst-allocate_once-mem.out: $(objpfx)tst-allocate_once.out
 	$(common-objpfx)malloc/mtrace $(objpfx)tst-allocate_once.mtrace > $@; \
 	$(evaluate-test)
 
+$(objpfx)tst-select: $(librt)
+$(objpfx)tst-select-time64: $(librt)
 $(objpfx)tst-pselect: $(librt)
 $(objpfx)tst-pselect-time64: $(librt)
diff --git a/misc/tst-select.c b/misc/tst-select.c
index 52aa266..134eed9 100644
--- a/misc/tst-select.c
+++ b/misc/tst-select.c
@@ -17,6 +17,7 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <errno.h>
+#include <intprops.h>
 #include <support/capture_subprocess.h>
 #include <support/check.h>
 #include <support/support.h>
@@ -32,12 +33,6 @@ struct child_args
 };
 
 static void
-alarm_handler (int signum)
-{
-  /* Do nothing.  */
-}
-
-static void
 do_test_child (void *clousure)
 {
   struct child_args *args = (struct child_args *) clousure;
@@ -69,17 +64,20 @@ do_test_child (void *clousure)
 static void
 do_test_child_alarm (void *clousure)
 {
-  struct sigaction act = { .sa_handler = alarm_handler };
-  xsigaction (SIGALRM, &act, NULL);
-  alarm (1);
+  struct child_args *args = (struct child_args *) clousure;
 
-  struct timeval tv = { .tv_sec = 10, .tv_usec = 0 };
+  support_create_timer (0, 100000000, false, NULL);
+  struct timeval tv = { .tv_sec = args->tmo.tv_sec, .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);
+  if (args->tmo.tv_sec > INT_MAX)
+    TEST_VERIFY (errno == EINTR || errno == EOVERFLOW);
+  else
+    {
+      TEST_COMPARE (errno, EINTR);
+      if (support_select_modifies_timeout ())
+       TEST_VERIFY (tv.tv_sec < args->tmo.tv_sec);
+    }
 }
 
 static int
@@ -121,13 +119,24 @@ do_test (void)
   xclose (args.fds[0][0]);
   xclose (args.fds[1][1]);
 
+  args.tmo = (struct timeval) { .tv_sec = 10, .tv_usec = 0 };
+  {
+    struct support_capture_subprocess result;
+    result = support_capture_subprocess (do_test_child_alarm, &args);
+    support_capture_subprocess_check (&result, "tst-select-child", 0,
+				      sc_allow_none);
+  }
+
+  args.tmo = (struct timeval) { .tv_sec = TYPE_MAXIMUM (time_t),
+				.tv_usec = 0 };
   {
     struct support_capture_subprocess result;
-    result = support_capture_subprocess (do_test_child_alarm, NULL);
+    result = support_capture_subprocess (do_test_child_alarm, &args);
     support_capture_subprocess_check (&result, "tst-select-child", 0,
 				      sc_allow_none);
   }
 
+  args.tmo = (struct timeval) { .tv_sec = 0, .tv_usec = 0 };
   {
     fd_set rfds;
     FD_ZERO (&rfds);
-- 
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