From: Jeff Dike Date: Mon, 10 Jul 2006 11:45:11 +0000 (-0700) Subject: [PATCH] uml: fix exitcall ordering bug X-Git-Tag: v2.6.18-rc2~156 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=61232f2fe44f7ac12d7512d099a8f10923eff7ea;p=linux-2.6 [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 Cc: Paolo 'Blaisorblade' Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/arch/um/os-Linux/sigio.c b/arch/um/os-Linux/sigio.c index 0d2422a7d7..d22623e8fc 100644 --- a/arch/um/os-Linux/sigio.c +++ b/arch/um/os-Linux/sigio.c @@ -191,6 +191,13 @@ int ignore_sigio_fd(int fd) 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 @@ int ignore_sigio_fd(int fd) update_thread(); out: sigio_unlock(); - return(err); + return err; } static struct pollfd *setup_initial_poll(int fd)