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authorMartin Peschke <mpeschke@linux.vnet.ibm.com>2013-08-22 17:45:37 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-08-29 09:47:39 -0700
commite1a289ee6734dd5f9a81a260f3027ad8010f530a (patch)
treee1fc09dfa08ffe812e7d7d3374b92925fe2055bb
parentbda5d1efa09527e443a6990f81459779a313e24d (diff)
SCSI: zfcp: fix schedule-inside-lock in scsi_device list loops
commit 924dd584b198a58aa7cb3efefd8a03326550ce8f upstream. 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> Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com> Signed-off-by: James Bottomley <JBottomley@Parallels.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/s390/scsi/zfcp_erp.c29
1 files changed, 22 insertions, 7 deletions
diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c
index 4133ab6e20f1..8e8f3533d2a1 100644
--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/drivers/s390/scsi/zfcp_erp.c
@@ -102,10 +102,13 @@ static void zfcp_erp_action_dismiss_port(struct zfcp_port *port)
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 @@ static void _zfcp_erp_lun_reopen_all(struct zfcp_port *port, int clear,
{
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)
@@ -1435,8 +1440,10 @@ void zfcp_erp_set_adapter_status(struct zfcp_adapter *adapter, u32 mask)
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);
}
/**
@@ -1470,11 +1477,13 @@ void zfcp_erp_clear_adapter_status(struct zfcp_adapter *adapter, u32 mask)
}
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);
}
/**
@@ -1488,16 +1497,19 @@ void zfcp_erp_set_port_status(struct zfcp_port *port, u32 mask)
{
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);
}
/**
@@ -1512,6 +1524,7 @@ void zfcp_erp_clear_port_status(struct zfcp_port *port, u32 mask)
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);
@@ -1521,13 +1534,15 @@ void zfcp_erp_clear_port_status(struct zfcp_port *port, u32 mask)
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);
}
/**