From: Tejun Heo Date: Mon, 11 Dec 2006 17:15:31 +0000 (+0900) Subject: [PATCH] libata: don't initialize sg in ata_exec_internal() if DMA_NONE (take #2) X-Git-Tag: firefly_0821_release~31863^2~5 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=33480a0ede8dcc7e6483054279008f972bd56fd3;p=firefly-linux-kernel-4.4.55.git [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: Tejun Heo Cc: Arnd Bergmann Signed-off-by: Jeff Garzik --- diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c index 011c0a8a2dcc..0d51d13b16bf 100644 --- a/drivers/ata/libata-core.c +++ b/drivers/ata/libata-core.c @@ -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; - sg_init_one(&sg, buf, buflen); + 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); } /**