Date: Sat, 11 Aug 2001 09:15:04 +0800 (+0800) From: Michael Robinson <robinson@netrinsics.com> To: current@freebsd.org Cc: hackers@freebsd.org Subject: _sigprocmask in malloc.c causes full file table? Message-ID: <200108110115.f7B1F4100321@netrinsics.com>
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I'm currently trying to deal with the problem where malloc/free in a
signal handler will crash (in my case, the X window server) if a signal
arrives during malloc or free.
Following the example of, e.g., stdlib/system.c, I tried blocking the usual
suspects (SIGIO, SIGWINCH, etc.), as follows:
void
free(void *ptr)
{
sigset_t old_procmask;
THREAD_LOCK();
_sigprocmask(SIG_BLOCK, &malloc_procmask, &old_procmask);
malloc_func = " in free():";
if (malloc_active++) {
wrtwarning("recursive call.\n");
} else {
ifree(ptr);
UTRACE(ptr, 0, 0);
}
malloc_active--;
_sigprocmask(SIG_SETMASK, &old_procmask, NULL);
THREAD_UNLOCK();
return;
}
That worked for the general case, but it broke mozilla in an interesting
way; mozilla would fail to create a kernel pipe in uthread_init.c, and I
would get a system error:
Aug 11 07:33:25 elephant /boot/kernel/kernel: file: table is full
Aug 11 07:33:25 elephant /boot/kernel/kernel: pid 358 (mozilla-bin), uid 1000: exited on signal 6 (core dumped)
I then changed the initialization of malloc_procmask so that it contained
no signals whatsoever, and the exact same thing happened.
I then commented out all calls to sigprocmask, and everything returned to
normal.
Am I doing something completely boneheaded, or is this an undocumented
subtle interaction?
-Michael Robinson
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