From b9c98c2a4580b94021266bbf3f4a70b6ca030558 Mon Sep 17 00:00:00 2001 From: Tony Battersby Date: Wed, 5 Mar 2008 10:23:26 -0600 Subject: [PATCH] SCSI: fix BUG when sum(scatterlist) > bufflen commit: 4d2de3a50ce19af2008a90636436a1bf5b3b697b When sending a SCSI command to a tape drive via the SCSI Generic (sg) driver, if the command has a data transfer length more than scatter_elem_sz (32 KB default) and not a multiple of 512, then I either hit BUG_ON(!valid_dma_direction(direction)) in dma_unmap_sg() or else the command never completes (depending on the LLDD). When constructing scatterlists, the sg driver rounds up the scatterlist element sizes to be a multiple of 512. This can result in sum(scatterlist lengths) > bufflen. In this case, scsi_req_map_sg() incorrectly sets bio->bi_size to sum(scatterlist lengths) rather than to bufflen. When the command completes, req_bio_endio() detects that bio->bi_size != 0, and so it doesn't call bio_endio(). This causes the command to be resubmitted, resulting in BUG_ON or the command never completing. This patch makes scsi_req_map_sg() set bio->bi_size to bufflen rather than to sum(scatterlist lengths), which fixes the problem. Signed-off-by: Tony Battersby Acked-by: Mike Christie Signed-off-by: James Bottomley Signed-off-by: Chris Wright Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/scsi_lib.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index a9ac5b1b1667..273728e1c9de 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -298,7 +298,6 @@ static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl, page = sg_page(sg); off = sg->offset; len = sg->length; - data_len += len; while (len > 0 && data_len > 0) { /* -- 2.39.5