[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: Nicholas Bellinger <nab@linux-iscsi.org>
Cc: stable@kernel.org
Signed-off-by: James Bottomley <jbottomley@parallels.com>

2 files changed, 6 insertions, 5 deletions

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index d25e20829012..fc10ed4ac493 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -150,13 +150,13 @@ out:
 
         {
         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);
         }
 
         /*
diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index 4a109835e420..59b8b9c5ad72 100644
--- a/drivers/target/target_core_tmr.c
+++ b/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",