From 3b661a92e869ebe2358de8f4b3230ad84f7fce51 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Thu, 21 Jun 2012 23:47:28 -0700 Subject: [SCSI] fix hot unplug vs async scan race The following crash results from cases where the end_device has been removed before scsi_sysfs_add_sdev has had a chance to run. BUG: unable to handle kernel NULL pointer dereference at 0000000000000098 IP: [] sysfs_create_dir+0x32/0xb6 ... Call Trace: [] kobject_add_internal+0x120/0x1e3 [] ? trace_hardirqs_on+0xd/0xf [] kobject_add_varg+0x41/0x50 [] kobject_add+0x64/0x66 [] device_add+0x12d/0x63a [] ? _raw_spin_unlock_irqrestore+0x47/0x56 [] ? module_refcount+0x89/0xa0 [] scsi_sysfs_add_sdev+0x4e/0x28a [] do_scan_async+0x9c/0x145 ...teach scsi_sysfs_add_devices() to check for deleted devices() before trying to add them, and teach scsi_remove_target() how to remove targets that have not been added via device_add(). Cc: Reported-by: Dariusz Majchrzak Signed-off-by: Dan Williams Signed-off-by: James Bottomley --- drivers/scsi/scsi_scan.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/scsi/scsi_scan.c') diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index 2e5fe584aad3..f55e5f166973 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -1717,6 +1717,9 @@ static void scsi_sysfs_add_devices(struct Scsi_Host *shost) { struct scsi_device *sdev; shost_for_each_device(sdev, shost) { + /* target removed before the device could be added */ + if (sdev->sdev_state == SDEV_DEL) + continue; if (!scsi_host_scan_allowed(shost) || scsi_sysfs_add_sdev(sdev) != 0) __scsi_remove_device(sdev); -- cgit