[SCSI] target: Fix interrupt context bug with stats_lock and core_tmr_alloc_req

This patch fixes two bugs wrt to the interrupt context usage of target
core with HW target mode drivers.  It first converts the usage of struct
se_device->stats_lock in transport_get_lun_for_cmd() and core_tmr_lun_reset()
to properly use spin_lock_irq() to address an BUG with CONFIG_LOCKDEP_SUPPORT=y
enabled.

This patch also adds a 'in_interrupt()' check to allow GFP_ATOMIC usage from
core_tmr_alloc_req() to fix a 'sleeping in interrupt context' BUG with HW
target fabrics that require this logic to function.
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>
Cc: stable@kernel.org
Signed-off-by: NJames Bottomley <jbottomley@parallels.com>

drivers/target/target_core_device.c

@@ -150,13 +150,13 @@ int transport_get_lun_for_cmd(
 
 	{
 	struct se_device *dev = se_lun->lun_se_dev;
-	spin_lock(&dev->stats_lock);
+	spin_lock_irq(&dev->stats_lock);
 	dev->num_cmds++;
 	if (se_cmd->data_direction == DMA_TO_DEVICE)
 		dev->write_bytes += se_cmd->data_length;
 	else if (se_cmd->data_direction == DMA_FROM_DEVICE)
 		dev->read_bytes += se_cmd->data_length;
-	spin_unlock(&dev->stats_lock);
+	spin_unlock_irq(&dev->stats_lock);
 	}
 
 	/*

drivers/target/target_core_tmr.c

@@ -55,7 +55,8 @@ struct se_tmr_req *core_tmr_alloc_req(
 {
 	struct se_tmr_req *tmr;
 
-	tmr = kmem_cache_zalloc(se_tmr_req_cache, GFP_KERNEL);
+	tmr = kmem_cache_zalloc(se_tmr_req_cache, (in_interrupt()) ?
+					GFP_ATOMIC : GFP_KERNEL);
 	if (!(tmr)) {
 		printk(KERN_ERR "Unable to allocate struct se_tmr_req\n");
 		return ERR_PTR(-ENOMEM);
@@ -398,9 +399,9 @@ int core_tmr_lun_reset(
 		printk(KERN_INFO "LUN_RESET: SCSI-2 Released reservation\n");
 	}
 
-	spin_lock(&dev->stats_lock);
+	spin_lock_irq(&dev->stats_lock);
 	dev->num_resets++;
-	spin_unlock(&dev->stats_lock);
+	spin_unlock_irq(&dev->stats_lock);
 
 	DEBUG_LR("LUN_RESET: %s for [%s] Complete\n",
 			(preempt_and_abort_list) ? "Preempt" : "TMR",