[073/146] [SCSI] target: Fix interrupt context bug with stats_lock and

Greg KH
2011-06-01T08:12:48Z

core_tmr_alloc_req

From: Nicholas Bellinger <nab@linux-iscsi.org>

commit 53ab6709b4d35b1924240854d794482fd7d33d4a upstream.

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>
Signed-off-by: James Bottomley <jbottomley@parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/target/target_core_device.c | 4 ++--
drivers/target/target_core_tmr.c | 7 ++++---
2 files changed, 6 insertions(+), 5 deletions(-)

--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -151,13 +151,13 @@ 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);
}

/*
--- 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",