[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: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/um/os-Linux/sigio.c b/arch/um/os-Linux/sigio.c
index 0d2422a..d22623e 100644
--- a/arch/um/os-Linux/sigio.c
+++ b/arch/um/os-Linux/sigio.c
@@ -191,6 +191,13 @@
struct pollfd *p;
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();
for(i = 0; i < current_poll.used; i++){
if(current_poll.poll[i].fd == fd) break;
@@ -215,7 +222,7 @@
update_thread();
out:
sigio_unlock();
- return(err);
+ return err;
}
static struct pollfd *setup_initial_poll(int fd)