Messages in this thread Patch in this message | | | Date | Fri, 21 Apr 2006 17:31:00 -0700 | From | Chris Spiegel <> | Subject | [PATCH] Exclude kernel threads from kill(-1, ..) |
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kill(-1, ..) currently will try to signal kernel threads, which of course won't die off even with SIGKILL, meaning that ESRCH will never be returned. Instead, allow kill() to return ESRCH if the only processes left are simply unkillable (kernel threads). This does not violate POSIX which says that "an unspecified set of system processes" may be excluded when killing -1.
Signed-off-by: Chris Spiegel <linuxml@happyjack.org>
--- (please CC replies to me)
There is a comment in signal.c which says that Linux's kill(-1, ..) does something that is probably wrong and should be like BSD or SysV. Well, this is a bit more like the modern BSDs (possibly SysV, I'm not familiar with it), although we still don't kill the calling process, a choice I agree with.
This isn't just a pathological fix, it's a problem I ran into with the following code (from NetBSD's /sbin/reboot):
for (i = 1;; ++i) { if (kill(-1, SIGKILL) == -1) { if (errno == ESRCH) break; goto restart; } if (i > 5) { warnx("WARNING: some process(es) wouldn't die"); break; } (void)sleep(2 * i); }
So it fixes a real-world (my world, anyway) problem.
--- linux-2.6/kernel/signal.c.orig 2006-04-21 15:44:17.618784128 -0700 +++ linux-2.6/kernel/signal.c 2006-04-21 16:20:52.269454557 -0700 @@ -1156,7 +1156,8 @@ static int kill_something_info(int sig, read_lock(&tasklist_lock); for_each_process(p) { - if (p->pid > 1 && p->tgid != current->tgid) { + if (p->pid > 1 && p->tgid != current->tgid && + p->mm != NULL) { int err = group_send_sig_info(sig, info, p); ++count; if (err != -EPERM) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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