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Commit 33480a0e authored by Tejun Heo's avatar Tejun Heo Committed by Jeff Garzik
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[PATCH] libata: don't initialize sg in ata_exec_internal() if DMA_NONE (take #2) 



Calling sg_init_one() with NULL buf causes oops on certain
configurations.  Don't initialize sg in ata_exec_internal() if
DMA_NONE and make the function complain if @buf is NULL when dma_dir
isn't DMA_NONE.  While at it, fix comment.

The problem is discovered and initial patch was submitted by Arnd
Bergmann.

Signed-off-by: default avatarTejun Heo <htejun@gmail.com>
Cc: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: default avatarJeff Garzik <jeff@garzik.org>
parent c10340ac

drivers/ata/libata-core.c

+10 −4
Original line number Diff line number Diff line
@@ -1332,7 +1332,7 @@ unsigned ata_exec_internal_sg(struct ata_device *dev, 
}



/**

 *	ata_exec_internal_sg - execute libata internal command

 *	ata_exec_internal - execute libata internal command

 *	@dev: Device to which the command is sent

 *	@tf: Taskfile registers for the command and the result

 *	@cdb: CDB for packet command
@@ -1353,11 +1353,17 @@ unsigned ata_exec_internal(struct ata_device *dev, 
			   struct ata_taskfile *tf, const u8 *cdb,

			   int dma_dir, void *buf, unsigned int buflen)

{

	struct scatterlist sg;

	struct scatterlist *psg = NULL, sg;

	unsigned int n_elem = 0;



	if (dma_dir != DMA_NONE) {

		WARN_ON(!buf);

		sg_init_one(&sg, buf, buflen);

		psg = &sg;

		n_elem++;

	}



	return ata_exec_internal_sg(dev, tf, cdb, dma_dir, &sg, 1);

	return ata_exec_internal_sg(dev, tf, cdb, dma_dir, psg, n_elem);

}



/**