linux-kernel - [PATCH RT] [scsi-qla2xxx] Fix BUG: sleeping function called from invalid context

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Date:	Fri, 27 Apr 2012 12:48:46 +0200
From:	John Kacur <jkacur@...hat.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	lkml <linux-kernel@...r.kernel.org>
Cc:	rt-users <linux-rt-users@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	David Sommerseth <davids@...hat.com>,
	John Kacur <jkacur@...hat.com>
Subject: [PATCH RT] [scsi-qla2xxx] Fix BUG: sleeping function called from invalid context

The relevant part of the traceback follows
[   11.307652]  [<ffffffff81077b27>] __might_sleep+0xe7/0x110
[   11.307663]  [<ffffffff8150e524>] rt_spin_lock+0x24/0x60
[   11.307670]  [<ffffffff8150da78>] ? rt_spin_lock_slowunlock+0x78/0x90
[   11.307703]  [<ffffffffa0272d83>] qla24xx_intr_handler+0x63/0x2d0 [qla2xxx]
[   11.307736]  [<ffffffffa0262307>] qla2x00_poll+0x67/0x90 [qla2xxx]

Function qla2x00_poll does local_irq_save() before calling qla24xx_intr_handler
which has a spinlock. Since spinlocks are sleepable on rt, it is not allowed
to call them with interrupts disabled. Therefore we use local_irq_save_nort()
instead which saves flags without disabling interrupts.

This fix needs to be applied to v3.0-rt, v3.2-rt and v3.4-rt

Suggested-by: Thomas Gleixner
Signed-off-by: John Kacur <jkacur@...hat.com>
---
 drivers/scsi/qla2xxx/qla_inline.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/qla2xxx/qla_inline.h b/drivers/scsi/qla2xxx/qla_inline.h
index 6e45764..28d9a8d 100644
--- a/drivers/scsi/qla2xxx/qla_inline.h
+++ b/drivers/scsi/qla2xxx/qla_inline.h
@@ -36,12 +36,12 @@ qla2x00_poll(struct rsp_que *rsp)
 {
 	unsigned long flags;
 	struct qla_hw_data *ha = rsp->hw;
-	local_irq_save(flags);
+	local_irq_save_nort(flags);
 	if (IS_QLA82XX(ha))
 		qla82xx_poll(0, rsp);
 	else
 		ha->isp_ops->intr_handler(0, rsp);
-	local_irq_restore(flags);
+	local_irq_restore_nort(flags);
 }
 
 static inline uint8_t *
-- 
1.7.1

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