linux-kernel - [PATCH 1/9] ipu_idmac: Use disable_irq

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Message-Id: <1239861252.29831.114.camel@linux-51e8.site>
Date:	Thu, 16 Apr 2009 15:54:12 +1000
From:	Ben Nizette <bn@...sdigital.com>
To:	dan.j.williams@...el.com
Cc:	linux-kernel <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/9] ipu_idmac: Use disable_irq_nosync() from within irq
	handlers.


disable_irq() should wait for all running handlers to complete
before returning.  As such, if it's used to disable an interrupt
from that interrupt's handler it will deadlock.  This replaces
the dangerous instances with the _nosync() variant which doesn't
have this problem.

Note the 2 handlers in question are only used #ifdef DEBUG so
I imagine these code paths don't get hit often.

Signed-off-by: Ben Nizette <bn@...sdigital.com>
---
diff --git a/drivers/dma/ipu/ipu_idmac.c b/drivers/dma/ipu/ipu_idmac.c
index e202a6c..3a4deea 100644
--- a/drivers/dma/ipu/ipu_idmac.c
+++ b/drivers/dma/ipu/ipu_idmac.c
@@ -1547,7 +1547,7 @@ static irqreturn_t ic_sof_irq(int irq, void *dev_id)
 	struct idmac_channel *ichan = dev_id;
 	printk(KERN_DEBUG "Got SOF IRQ %d on Channel %d\n",
 	       irq, ichan->dma_chan.chan_id);
-	disable_irq(irq);
+	disable_irq_nosync(irq);
 	return IRQ_HANDLED;
 }
 
@@ -1556,7 +1556,7 @@ static irqreturn_t ic_eof_irq(int irq, void *dev_id)
 	struct idmac_channel *ichan = dev_id;
 	printk(KERN_DEBUG "Got EOF IRQ %d on Channel %d\n",
 	       irq, ichan->dma_chan.chan_id);
-	disable_irq(irq);
+	disable_irq_nosync(irq);
 	return IRQ_HANDLED;
 }
 
-- 
1.6.0.2



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