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| author | Tony Battersby <tonyb@cybernetics.com> | 2008-02-05 10:36:10 -0500 |
|---|---|---|
| committer | James Bottomley <James.Bottomley@HansenPartnership.com> | 2008-02-07 18:02:44 -0600 |
| commit | 4d2de3a50ce19af2008a90636436a1bf5b3b697b (patch) | |
| tree | 7bf2d1974e54567cba53f258ccfaaa8d9922319a /drivers/scsi | |
| parent | 76d78300a6eb8b7f08e47703b7e68a659ffc2053 (diff) | |
| download | lwn-4d2de3a50ce19af2008a90636436a1bf5b3b697b.tar.gz lwn-4d2de3a50ce19af2008a90636436a1bf5b3b697b.zip | |
[SCSI] fix BUG when sum(scatterlist) > bufflen
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 <tonyb@cybernetics.com>
Acked-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Diffstat (limited to 'drivers/scsi')
| -rw-r--r-- | drivers/scsi/scsi_lib.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index f243fc30c908..135c1d054701 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -301,7 +301,6 @@ 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) { /* |