[PATCH] firewire: time out in fw_core_remove_card

[PATCH] firewire: time out in fw_core_remove_card

[Stefan Richter]

This allows "modprobe -r firewire-ohci" (or card unbinding in general)
to proceed after 40 seconds even if there is a reference counting bug or
other shutdown bug in upper layers.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
 drivers/firewire/fw-card.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Index: linux/drivers/firewire/fw-card.c
===================================================================
--- linux.orig/drivers/firewire/fw-card.c
+++ linux/drivers/firewire/fw-card.c
@@ -16,6 +16,7 @@
  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */
 
+#include <linux/bug.h>
 #include <linux/completion.h>
 #include <linux/crc-itu-t.h>
 #include <linux/delay.h>
@@ -508,7 +509,8 @@ fw_core_remove_card(struct fw_card *card
 
 	/* Wait for all users, especially device workqueue jobs, to finish. */
 	fw_card_put(card);
-	wait_for_completion(&card->done);
+	WARN(wait_for_completion_timeout(&card->done, 40 * HZ) == 0,
+	     KBUILD_MODNAME ": forced card shutdown with references held\n");
 
 	cancel_delayed_work_sync(&card->work);
 	WARN_ON(!list_empty(&card->transaction_list));

-- 
Stefan Richter
-=====-==--- =--= -===-
http://arcgraph.de/sr/

Re: [PATCH] firewire: time out in fw_core_remove_card

[Stefan Richter]

I wrote:
> This allows "modprobe -r firewire-ohci" (or card unbinding in general)
> to proceed after 40 seconds even if there is a reference counting bug or
> other shutdown bug in upper layers.

Hmm, this doesn't work quite perfectly yet if there are userspace 
clients which keep a device open.  fw-cdev needs to be trained to let go 
of a device as gracefully as fw-sbp2 does nowadays.
-- 
Stefan Richter
-=====-==--- =--= -===-
http://arcgraph.de/sr/