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Commit 61232f2f authored by Jeff Dike's avatar Jeff Dike Committed by Linus Torvalds
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[PATCH] uml: fix exitcall ordering bug 



This fixes an exitcall ordering bug - calls to ignore_sigio_fd can come from
exitcalls that come after the sigio thread has been killed.  This would cause
shutdown to hang or crash.

Fixed by having ignore_sigio_fd check that the thread is present before trying
to communicate with it.

Signed-off-by: default avatarJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 8e64d96a

arch/um/os-Linux/sigio.c

+8 −1
Original line number Original line Diff line number Diff line
@@ -191,6 +191,13 @@ int ignore_sigio_fd(int fd) 
	struct pollfd *p;

	struct pollfd *p;

	int err = 0, i, n = 0;

	int err = 0, i, n = 0;





	/* This is called from exitcalls elsewhere in UML - if

	 * sigio_cleanup has already run, then update_thread will hang

	 * or fail because the thread is no longer running.

	 */

	if(write_sigio_pid == -1)

		return -EIO;



	sigio_lock();

	sigio_lock();

	for(i = 0; i < current_poll.used; i++){

	for(i = 0; i < current_poll.used; i++){

		if(current_poll.poll[i].fd == fd) break;

		if(current_poll.poll[i].fd == fd) break;
@@ -215,7 +222,7 @@ int ignore_sigio_fd(int fd) 
	update_thread();

	update_thread();

 out:

 out:

	sigio_unlock();

	sigio_unlock();

	return(err);

	return err;

}

}





static struct pollfd *setup_initial_poll(int fd)

static struct pollfd *setup_initial_poll(int fd)