Messages in this thread Patches in this message | | | Date | Fri, 22 Oct 2004 21:29:24 -0700 | From | Roland McGrath <> | Subject | Re: Fw: BUG_ONs in signal.c? |
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Oh, duh. The race is obvious. Sorry for the confusion there. I think this is the way to fix it.
--- linux-2.6/kernel/signal.c 19 Oct 2004 15:03:02 -0000 1.143 +++ linux-2.6/kernel/signal.c 23 Oct 2004 04:23:31 -0000 @@ -1909,22 +1910,16 @@ relock: * Anything else is fatal, maybe with a core dump. */ current->flags |= PF_SIGNALED; - if (sig_kernel_coredump(signr) && - do_coredump((long)signr, signr, regs)) { + if (sig_kernel_coredump(signr)) { /* - * That killed all other threads in the group and - * synchronized with their demise, so there can't - * be any more left to kill now. The group_exit - * flags are set by do_coredump. Note that - * thread_group_empty won't always be true yet, - * because those threads were blocked in __exit_mm - * and we just let them go to finish dying. - */ - const int code = signr | 0x80; - BUG_ON(!current->signal->group_exit); - BUG_ON(current->signal->group_exit_code != code); - do_exit(code); - /* NOTREACHED */ + * If it was able to dump core, this kills all + * other threads in the group and synchronizes with + * their demise. If we lost the race with another + * thread getting here, it set group_exit_code + * first and our do_group_exit call below will use + * that value and ignore the one we pass it. + */ + do_coredump((long)signr, signr, regs); } /*
While looking at this, I noticed a bug (not directly related) in do_coredump. It was setting the "core dumped" flag even when the format dumping hook failed (e.g. for memory allocation failures).
--- linux-2.6/fs/exec.c 19 Oct 2004 15:05:13 -0000 1.146 +++ linux-2.6/fs/exec.c 23 Oct 2004 04:23:42 -0000 @@ -1417,7 +1417,8 @@ int do_coredump(long signr, int exit_cod retval = binfmt->core_dump(signr, regs, file); - current->signal->group_exit_code |= 0x80; + if (retval) + current->signal->group_exit_code |= 0x80; close_fail: filp_close(file, NULL); fail_unlock:
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