Commits
Martin Peschke committed 924dd584b19
[SCSI] zfcp: fix schedule-inside-lock in scsi_device list loops BUG: sleeping function called from invalid context at kernel/workqueue.c:2752 in_atomic(): 1, irqs_disabled(): 1, pid: 360, name: zfcperp0.0.1700 CPU: 1 Not tainted 3.9.3+ #69 Process zfcperp0.0.1700 (pid: 360, task: 0000000075b7e080, ksp: 000000007476bc30) <snip> Call Trace: ([<00000000001165de>] show_trace+0x106/0x154) [<00000000001166a0>] show_stack+0x74/0xf4 [<00000000006ff646>] dump_stack+0xc6/0xd4 [<000000000017f3a0>] __might_sleep+0x128/0x148 [<000000000015ece8>] flush_work+0x54/0x1f8 [<00000000001630de>] __cancel_work_timer+0xc6/0x128 [<00000000005067ac>] scsi_device_dev_release_usercontext+0x164/0x23c [<0000000000161816>] execute_in_process_context+0x96/0xa8 [<00000000004d33d8>] device_release+0x60/0xc0 [<000000000048af48>] kobject_release+0xa8/0x1c4 [<00000000004f4bf2>] __scsi_iterate_devices+0xfa/0x130 [<000003ff801b307a>] zfcp_erp_strategy+0x4da/0x1014 [zfcp] [<000003ff801b3caa>] zfcp_erp_thread+0xf6/0x2b0 [zfcp] [<000000000016b75a>] kthread+0xf2/0xfc [<000000000070c9de>] kernel_thread_starter+0x6/0xc [<000000000070c9d8>] kernel_thread_starter+0x0/0xc Apparently, the ref_count for some scsi_device drops down to zero, triggering device removal through execute_in_process_context(), while the lldd error recovery thread iterates through a scsi device list. Unfortunately, execute_in_process_context() decides to immediately execute that device removal function, instead of scheduling asynchronous execution, since it detects process context and thinks it is safe to do so. But almost all calls to shost_for_each_device() in our lldd are inside spin_lock_irq, even in thread context. Obviously, schedule() inside spin_lock_irq sections is a bad idea. Change the lldd to use the proper iterator function, __shost_for_each_device(), in combination with required locking. Occurences that need to be changed include all calls in zfcp_erp.c, since those might be executed in zfcp error recovery thread context with a lock held. Other occurences of shost_for_each_device() in zfcp_fsf.c do not need to be changed (no process context, no surrounding locking). The problem was introduced in Linux 2.6.37 by commit b62a8d9b45b971a67a0f8413338c230e3117dff5 "[SCSI] zfcp: Use SCSI device data zfcp_scsi_dev instead of zfcp_unit". Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Martin Peschke <mpeschke@linux.vnet.ibm.com> Cc: stable@vger.kernel.org #2.6.37+ Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com> Signed-off-by: James Bottomley <JBottomley@Parallels.com>