[LTP] [PATCH v2] lib: shell: Fix timeout process races

[Li Wang]

Hi Cyril,



> +++ b/testcases/lib/tst_timeout_kill.c
> @@ -0,0 +1,75 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2021 Cyril Hrubis <chrubis@suse.cz>
> + */
> +
> +#include <stdio.h>
> +#include <signal.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +#include <errno.h>
> +#include <string.h>
> +
> +static void print_help(const char *name)
> +{
> +       fprintf(stderr, "usage: %s timeout pid\n", name);
> +}
> +
> +#define print_msg(fmt, ...) fprintf(stderr, fmt "\n", ##__VA_ARGS__)
> +
> +int main(int argc, char *argv[])
> +{
> +       int timeout, pid, ret, i;
> +
> +       if (argc != 3) {
> +               print_help(argv[0]);
> +               return 1;
> +       }
> +
> +       timeout = atoi(argv[1]);
> +       pid = atoi(argv[2]);
> +
> +       if (timeout < 0) {
> +               fprintf(stderr, "Invalid timeout '%s'\n", argv[1]);
> +               print_help(argv[0]);
> +               return 1;
> +       }
> +
> +       if (pid <= 1) {
> +               fprintf(stderr, "Invalid pid '%s'\n", argv[2]);
> +               print_help(argv[0]);
> +               return 1;
> +       }
> +
> +       if (timeout)
> +               sleep(timeout);
> +
> +       print_msg("Test timed out, sending SIGTERM!");
> +       print_msg("If you are running on slow machine, try exporting
> LTP_TIMEOUT_MUL > 1");
> +
> +       ret = kill(-pid, SIGTERM);
>

This 'pid' is the parent shell process id, so it obviously that
tst_timeout_kill
process would get signal SIGTERM as well.

I'm thinking maybe we should let tst_timeout_kill itself ignore SIGTERM
otherwise we have no chance to perform the following double-check code?



> +       if (ret) {
> +               print_msg("kill(%i) failed: %s", -pid, strerror(errno));
> +               return 1;
> +       }
> +
> +       usleep(100000);
> +
> +       i = 10;
> +
> +       while (!kill(-pid, 0) && i-- > 0) {
>

And just check 'pid' but not '-pid' as original shell behavior?


> +               print_msg("Test is still running...");
> +               sleep(1);
> +       }
> +
> +       if (!kill(-pid, 0)) {
>

check pid, if so like that.


> +               print_msg("Test is still running, sending SIGKILL");
> +               ret = kill(-pid, SIGKILL);
> +               if (ret) {
> +                       print_msg("kill(%i) failed: %s", -pid,
> strerror(errno));
> +                       return 1;
> +               }
> +       }
> +
> +       return 0;
> +}
> --
> 2.32.0
>
>
> --
> Mailing list info: https://lists.linux.it/listinfo/ltp
>
>

-- 
Regards,
Li Wang
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.linux.it/pipermail/ltp/attachments/20210921/c5169ccd/attachment.htm>