[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>
diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c
index 1d4c8fe..c82fe65 100644
--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/drivers/s390/scsi/zfcp_erp.c
@@ -102,10 +102,13 @@
if (atomic_read(&port->status) & ZFCP_STATUS_COMMON_ERP_INUSE)
zfcp_erp_action_dismiss(&port->erp_action);
- else
- shost_for_each_device(sdev, port->adapter->scsi_host)
+ else {
+ spin_lock(port->adapter->scsi_host->host_lock);
+ __shost_for_each_device(sdev, port->adapter->scsi_host)
if (sdev_to_zfcp(sdev)->port == port)
zfcp_erp_action_dismiss_lun(sdev);
+ spin_unlock(port->adapter->scsi_host->host_lock);
+ }
}
static void zfcp_erp_action_dismiss_adapter(struct zfcp_adapter *adapter)
@@ -592,9 +595,11 @@
{
struct scsi_device *sdev;
- shost_for_each_device(sdev, port->adapter->scsi_host)
+ spin_lock(port->adapter->scsi_host->host_lock);
+ __shost_for_each_device(sdev, port->adapter->scsi_host)
if (sdev_to_zfcp(sdev)->port == port)
_zfcp_erp_lun_reopen(sdev, clear, id, 0);
+ spin_unlock(port->adapter->scsi_host->host_lock);
}
static void zfcp_erp_strategy_followup_failed(struct zfcp_erp_action *act)
@@ -1434,8 +1439,10 @@
atomic_set_mask(common_mask, &port->status);
read_unlock_irqrestore(&adapter->port_list_lock, flags);
- shost_for_each_device(sdev, adapter->scsi_host)
+ spin_lock_irqsave(adapter->scsi_host->host_lock, flags);
+ __shost_for_each_device(sdev, adapter->scsi_host)
atomic_set_mask(common_mask, &sdev_to_zfcp(sdev)->status);
+ spin_unlock_irqrestore(adapter->scsi_host->host_lock, flags);
}
/**
@@ -1469,11 +1476,13 @@
}
read_unlock_irqrestore(&adapter->port_list_lock, flags);
- shost_for_each_device(sdev, adapter->scsi_host) {
+ spin_lock_irqsave(adapter->scsi_host->host_lock, flags);
+ __shost_for_each_device(sdev, adapter->scsi_host) {
atomic_clear_mask(common_mask, &sdev_to_zfcp(sdev)->status);
if (clear_counter)
atomic_set(&sdev_to_zfcp(sdev)->erp_counter, 0);
}
+ spin_unlock_irqrestore(adapter->scsi_host->host_lock, flags);
}
/**
@@ -1487,16 +1496,19 @@
{
struct scsi_device *sdev;
u32 common_mask = mask & ZFCP_COMMON_FLAGS;
+ unsigned long flags;
atomic_set_mask(mask, &port->status);
if (!common_mask)
return;
- shost_for_each_device(sdev, port->adapter->scsi_host)
+ spin_lock_irqsave(port->adapter->scsi_host->host_lock, flags);
+ __shost_for_each_device(sdev, port->adapter->scsi_host)
if (sdev_to_zfcp(sdev)->port == port)
atomic_set_mask(common_mask,
&sdev_to_zfcp(sdev)->status);
+ spin_unlock_irqrestore(port->adapter->scsi_host->host_lock, flags);
}
/**
@@ -1511,6 +1523,7 @@
struct scsi_device *sdev;
u32 common_mask = mask & ZFCP_COMMON_FLAGS;
u32 clear_counter = mask & ZFCP_STATUS_COMMON_ERP_FAILED;
+ unsigned long flags;
atomic_clear_mask(mask, &port->status);
@@ -1520,13 +1533,15 @@
if (clear_counter)
atomic_set(&port->erp_counter, 0);
- shost_for_each_device(sdev, port->adapter->scsi_host)
+ spin_lock_irqsave(port->adapter->scsi_host->host_lock, flags);
+ __shost_for_each_device(sdev, port->adapter->scsi_host)
if (sdev_to_zfcp(sdev)->port == port) {
atomic_clear_mask(common_mask,
&sdev_to_zfcp(sdev)->status);
if (clear_counter)
atomic_set(&sdev_to_zfcp(sdev)->erp_counter, 0);
}
+ spin_unlock_irqrestore(port->adapter->scsi_host->host_lock, flags);
}
/**