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authorChristof Schmitt <christof.schmitt@de.ibm.com>2010-10-06 13:19:44 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2010-11-22 10:43:10 -0800
commit7a951eac442423d9200a4767d4dd5b656103b93c (patch)
treed63c796a4285b3ce5621f41efedab981264ad764
parentc47f5a57a00ee2aa37130d128ae21ee8700dde4d (diff)
Fix race when removing SCSI devices
commit 546ae796bfac6399e30da4b5af2cf7a6d0f8a4ec upstream. Removing SCSI devices through echo 1 > /sys/bus/scsi/devices/ ... /delete while the FC transport class removes the SCSI target can lead to an oops: Unable to handle kernel pointer dereference at virtual kernel address 00000000b6815000 Oops: 0011 [#1] PREEMPT SMP DEBUG_PAGEALLOC Modules linked in: sunrpc qeth_l3 binfmt_misc dm_multipath scsi_dh dm_mod ipv6 qeth ccwgroup [last unloaded: scsi_wait_scan] CPU: 1 Not tainted 2.6.35.5-45.x.20100924-s390xdefault #1 Process fc_wq_0 (pid: 861, task: 00000000b7331240, ksp: 00000000b735bac0) Krnl PSW : 0704200180000000 00000000003ff6e4 (__scsi_remove_device+0x24/0xd0) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:2 PM:0 EA:3 Krnl GPRS: 0000000000000001 0000000000000000 00000000b6815000 00000000bc24a8c0 00000000003ff7c8 000000000056dbb8 0000000000000002 0000000000835d80 ffffffff00000000 0000000000001000 00000000b6815000 00000000bc24a7f0 00000000b68151a0 00000000b6815000 00000000b735bc20 00000000b735bbf8 Krnl Code: 00000000003ff6d6: a7840001 brc 8,3ff6d8 00000000003ff6da: a7fbffd8 aghi %r15,-40 00000000003ff6de: e3e0f0980024 stg %r14,152(%r15) >00000000003ff6e4: e31021200004 lg %r1,288(%r2) 00000000003ff6ea: a71f0000 cghi %r1,0 00000000003ff6ee: a7a40011 brc 10,3ff710 00000000003ff6f2: a7390003 lghi %r3,3 00000000003ff6f6: c0e5ffffc8b1 brasl %r14,3f8858 Call Trace: ([<0000000000001000>] 0x1000) [<00000000003ff7d2>] scsi_remove_device+0x42/0x54 [<00000000003ff8ba>] __scsi_remove_target+0xca/0xfc [<00000000003ff99a>] __remove_child+0x3a/0x48 [<00000000003e3246>] device_for_each_child+0x72/0xbc [<00000000003ff93a>] scsi_remove_target+0x4e/0x74 [<0000000000406586>] fc_rport_final_delete+0xb2/0x23c [<000000000015d080>] worker_thread+0x200/0x344 [<000000000016330c>] kthread+0xa0/0xa8 [<0000000000106c1a>] kernel_thread_starter+0x6/0xc [<0000000000106c14>] kernel_thread_starter+0x0/0xc INFO: lockdep is turned off. Last Breaking-Event-Address: [<00000000003ff7cc>] scsi_remove_device+0x3c/0x54 The function __scsi_remove_target iterates through the SCSI devices on the host, but it drops the host_lock before calling scsi_remove_device. When the SCSI device is deleted from another thread, the pointer to the SCSI device in scsi_remove_device can become invalid. Fix this by getting a reference to the SCSI device before dropping the host_lock to keep the SCSI device alive for the call to scsi_remove_device. Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com> Signed-off-by: James Bottomley <James.Bottomley@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/scsi/scsi_sysfs.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index ab3c71869be5..2aafca0fe5e6 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -979,10 +979,11 @@ static void __scsi_remove_target(struct scsi_target *starget)
list_for_each_entry(sdev, &shost->__devices, siblings) {
if (sdev->channel != starget->channel ||
sdev->id != starget->id ||
- sdev->sdev_state == SDEV_DEL)
+ scsi_device_get(sdev))
continue;
spin_unlock_irqrestore(shost->host_lock, flags);
scsi_remove_device(sdev);
+ scsi_device_put(sdev);
spin_lock_irqsave(shost->host_lock, flags);
goto restart;
}