Re: [BUG] 2.5.62 kmod rewrite broke modprobe's install command

[Rusty Russell]

In message <[e-mail]> you write:
> The reason this happens is that in 2.5.62, modprobe is started
> with SIGCHLD set to SIG_IGN and not blocked. The "install"
> command is run by system(), but due to SIGCHLD being SIG_IGN,
> the child (which terminates quickly) is reaped automatically.
> The parent process (modprobe) does a wait or waitpid, which fails
> with ECHILD since the child is already gone. system() returns -1,
> and modprobe logs a fatal error.

Yes.  Fixed below.

Thanks for the report!
Rusty.
--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.

Name: Enable signals for usermode helpers
Author: Linus Torvalds
Status: Experimental

D: Stelian Pop reported that all signals are blocked in processes
D: execed from the kernel as usermode helpers.

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.62-bk6/kernel/kmod.c working-2.5.62-bk6-usermode-sig/kernel/kmod.c
--- linux-2.5.62-bk6/kernel/kmod.c	2003-02-18 11:18:57.000000000 +1100
+++ working-2.5.62-bk6-usermode-sig/kernel/kmod.c	2003-02-24 12:18:55.000000000 +1100
@@ -152,6 +152,14 @@ static int ____call_usermodehelper(void 
 	struct subprocess_info *sub_info = data;
 	int retval;
 
+	/* Unblock all signals. */
+	flush_signals(curtask);
+	flush_signal_handlers(curtask);
+	spin_lock_irq(&curtask->sighand->siglock);
+	sigemptyset(&curtask->blocked);
+	recalc_sigpending();
+	spin_unlock_irq(&curtask->sighand->siglock);
+
 	retval = -EPERM;
 	if (current->fs->root)
 		retval = execve(sub_info->path, sub_info->argv,sub_info->envp);