[PATCH] target: Make transport_lookup_cmd_lun() locking IRQ-safe

[Roland Dreier <roland@kernel.org>]

From: Roland Dreier <roland@purestorage.com>

transport_lookup_cmd_lun() may be called from interrupt context (eg
tcm_loop_allocate_core_cmd() calls it, and it has a comment that says,
"Can be called from interrupt context"), so it needs to use
spin_lock_irqsave() instead of spin_lock_irq() to avoid enabling
interrupts at the wrong time.

(And indeed the last set of lock operations, on lun_cmd_lock, were
already using spin_lock_irqsave(), so we just need to fix the other
two locks we take)

Signed-off-by: Roland Dreier <roland@purestorage.com>
---
Not sure if this is causing anything other than lockdep reports at
the moment, so I don't think it's worth trying to get into 3.0.0-rc...

 drivers/target/target_core_device.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index fcb8161..ca0ba71 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -72,7 +72,7 @@ int transport_lookup_cmd_lun(struct se_cmd *se_cmd, u32 unpacked_lun)
 		return -ENODEV;
 	}
 
-	spin_lock_irq(&se_sess->se_node_acl->device_list_lock);
+	spin_lock_irqsave(&se_sess->se_node_acl->device_list_lock, flags);
 	se_cmd->se_deve = &se_sess->se_node_acl->device_list[unpacked_lun];
 
 	if (se_cmd->se_deve->lun_flags & TRANSPORT_LUNFLAGS_INITIATOR_ACCESS) {
@@ -89,7 +89,7 @@ int transport_lookup_cmd_lun(struct se_cmd *se_cmd, u32 unpacked_lun)
 			       " Access for 0x%08x\n",
 			       se_cmd->se_tfo->get_fabric_name(),
 			       unpacked_lun);
-			spin_unlock_irq(&se_sess->se_node_acl->device_list_lock);
+			spin_unlock_irqrestore(&se_sess->se_node_acl->device_list_lock, flags);
 			return -EACCES;
 		}
 
@@ -107,7 +107,7 @@ int transport_lookup_cmd_lun(struct se_cmd *se_cmd, u32 unpacked_lun)
 		se_cmd->se_orig_obj_ptr = se_cmd->se_lun->lun_se_dev;
 		se_cmd->se_cmd_flags |= SCF_SE_LUN_CMD;
 	}
-	spin_unlock_irq(&se_sess->se_node_acl->device_list_lock);
+	spin_unlock_irqrestore(&se_sess->se_node_acl->device_list_lock, flags);
 
 	if (!se_lun) {
 		/*
@@ -156,13 +156,13 @@ int transport_lookup_cmd_lun(struct se_cmd *se_cmd, u32 unpacked_lun)
 
 	/* TODO: get rid of this and use atomics for stats */
 	dev = se_lun->lun_se_dev;
-	spin_lock_irq(&dev->stats_lock);
+	spin_lock_irqsave(&dev->stats_lock, flags);
 	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_irq(&dev->stats_lock);
+	spin_unlock_irqrestore(&dev->stats_lock, flags);
 
 	/*
 	 * Add the iscsi_cmd_t to the struct se_lun's cmd list.  This list is used