[PATCH] firewire: fail open() quickly if the node doesn't exist anymore

[Stefan Richter <stefanr@s5r6.in-berlin.de>]

Scenario:  Process A keeps the character device file of node N open.
N is being unplugged.  File /dev/fwN won't be destroyed as long as A
doesn't close it.  Now, process B opens /dev/fwN as well.  Previously
it would succeed but be unable to do any IO on it of course.  With this
patch, process B's open() will fail immediately with -ENODEV.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
 drivers/firewire/fw-device.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

Index: linux/drivers/firewire/fw-device.c
===================================================================
--- linux.orig/drivers/firewire/fw-device.c
+++ linux/drivers/firewire/fw-device.c
@@ -616,8 +616,12 @@ struct fw_device *fw_device_from_devt(de
 
 	down_read(&idr_rwsem);
 	device = idr_find(&fw_device_idr, MINOR(devt));
-	if (device)
-		fw_device_get(device);
+	if (device) {
+		if (fw_device_is_shutdown(device))
+			device = NULL;
+		else
+			fw_device_get(device);
+	}
 	up_read(&idr_rwsem);
 
 	return device;

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