Re: [PATCH] pcmcia driver model support [4/5]

[Adam Belay <ambx1@neo.rr.com>]

On Fri, Aug 06, 2004 at 10:35:38AM +0000, Adam Belay wrote:
> On Fri, Aug 06, 2004 at 11:43:20AM +0100, Russell King wrote:
> > On Thu, Aug 05, 2004 at 10:28:20PM +0000, Adam Belay wrote:
> > > It is not safe to use the skt_sem in pcmcia_validate_mem.  This patch
> > > fixes a real world bug, and without it many systems will fail to shutdown
> > > properly.
> > 
> > However, we need to take this semaphore here to prevent the socket state
> > changing.  It sounds from your description that we're hitting yet another
> > stupid recursion bug in PCMCIA...
> 
> It's worth noting that we don't hold skt_sem in pcmcia_get_first_tuple (and
> possibly others), but we probably should be.  This may have been to prevent
> recursion bugs.
> 
> > 
> > It sounds like we shouldn't be holding skt_sem when we wait for userspace
> > to reply to the ejection request.
> 
> The situation is rather complicated.  pcmcia_eject_card itself has to hold
> skt_sem to ensure the socket state remains correct.  We could always release
> the semaphore while sending the event, and then grab it again.  Of course we
> would have to check if the socket is still present a second time in the same
> function.  How does this look (untested)?

Sorry, the last patch was incorrect.

--- a/drivers/pcmcia/cs.c	2004-08-05 21:28:48.000000000 +0000
+++ b/drivers/pcmcia/cs.c	2004-08-06 10:42:34.000000000 +0000
@@ -2056,9 +2056,14 @@
 			break;
 		}
 
+		up(&skt->skt_sem);
 		ret = send_event(skt, CS_EVENT_EJECTION_REQUEST, CS_EVENT_PRI_LOW);
-		if (ret != 0) {
-			ret = -EINVAL;
+		if (ret != 0)
+			return -EINVAL;
+		down(&skt->skt_sem);
+
+		if (!(skt->state & SOCKET_PRESENT)) {
+			ret = -ENODEV;
 			break;
 		}