[Patch] Fix oops on rmmod usb-storage

Hannes Reinecke
2004-09-29T07:47:36Z

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Hi all,

I managed to (hopefully) fix an kernel Oops on rmmod usb-storage.
The Oops we got was something like:

usbcore: deregistering driver usb-storage
scsi: Device offlined - not ready after error recovery: host 0 channel 0
id 0 lun 0
sr 0:0:0:0: Illegal state transition cancel->offline
Badness in scsi_device_set_state at drivers/scsi/scsi_lib.c:1688
[<e12bab6e>] scsi_device_set_state+0x9e/0xd0 [scsi_mod]
[<e12b8a6e>] scsi_eh_offline_sdevs+0x4e/0x70 [scsi_mod]
[<e12b8f1a>] scsi_unjam_host+0x9a/0x1b0 [scsi_mod]
[<e12b90f5>] scsi_error_handler+0xc5/0x160 [scsi_mod]
[<e12b9030>] scsi_error_handler+0x0/0x160 [scsi_mod]
[<c0104255>] kernel_thread_helper+0x5/0x10

It turned out that in drivers/scsi/hosts.c:scsi_remove_host()
first the host is removed with scsi_forget_host() and _then_ all
outstanding I/O to this host is cancelled with scsi_host_cancel().
Sounds a bit fishy as scsi_host_cancel() tries to talk to a host which
we just have deleted ...
(Incidentally, this is most likely the same bug as Bug #2752 and #3480
from bugme.osdl.org :-).
(And also #133249 from bugzilla.redhat.com :-).

The attached patch corrects this.
Please apply.

Cheers,

Hannes
--
Dr. Hannes Reinecke hare@suse.de
SuSE Linux AG S390 & zSeries
Maxfeldstraße 5 +49 911 74053 688
90409 Nürnberg http://www.suse.de

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# This is a BitKeeper generated diff -Nru style patch.
#
# ChangeSet
# 2004/09/29 09:27:51+02:00 hare@lammermuir.suse.de
# We really should cancel I/O requests before removing the host.
#
# Signed-off-by: Hannes Reinecke <hare@suse.de>
#
# drivers/scsi/hosts.c
# 2004/09/29 09:27:46+02:00 hare@lammermuir.suse.de +1 -1
# Change ordering to cancel I/O-request before removing the host.
#
diff -Nru a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
--- a/drivers/scsi/hosts.c 2004-09-29 09:29:19 +02:00
+++ b/drivers/scsi/hosts.c 2004-09-29 09:29:19 +02:00
@@ -75,8 +75,8 @@
**/
void scsi_remove_host(struct Scsi_Host *shost)
{
- scsi_forget_host(shost);
scsi_host_cancel(shost, 0);
+ scsi_forget_host(shost);
scsi_proc_host_rm(shost);

set_bit(SHOST_DEL, &shost->shost_state);