linux-kernel - [PATCH 2/6] target: Fix interrupt context bug with stats_lock and core_tmr_alloc

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Message-Id: <1305861554-29960-3-git-send-email-nab@linux-iscsi.org>
Date:	Thu, 19 May 2011 20:19:10 -0700
From:	"Nicholas A. Bellinger" <nab@...ux-iscsi.org>
To:	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-scsi <linux-scsi@...r.kernel.org>,
	James Bottomley <James.Bottomley@...senPartnership.com>
Cc:	Christoph Hellwig <hch@....de>, Hannes Reinecke <hare@...e.de>,
	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
	Andy Grover <agrover@...hat.com>,
	Mike Christie <michaelc@...wisc.edu>,
	Boaz Harrosh <bharrosh@...asas.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Martin Svec <martin.svec@...er.cz>,
	Nicholas Bellinger <nab@...ux-iscsi.org>
Subject: [PATCH 2/6] target: Fix interrupt context bug with stats_lock and core_tmr_alloc_req

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

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

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index d25e208..fc10ed4 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 4a10983..59b8b9c 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",
-- 
1.7.5.1

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