Messages in this thread Patch in this message | | | From | Rusty Russell <> | Subject | Re: [PATCH] Attempt to get eject failures back to ioctl(CDROMEJECT) | Date | Thu, 15 Nov 2007 22:32:02 +1100 |
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On Thursday 15 November 2007 19:47:05 Jens Axboe wrote: > On Thu, Nov 15 2007, Rusty Russell wrote: > > If blk_rq_map_sg returns more than was allocated, it's a bug, and > > something's already been overwritten. BUG_ON() is probably the right > > thing here. > > It really just means that it mapped more segments than the block layer > said it would. Usually that wont overwrite memory here since scsi rounds > up on allocating the sg list, but it indeed can. Similar code has been > in scsi_lib.c for ages, I'd suggest covering that in the same patch.
Good point. I assume that you've not seen these printks in recent memory?
This covers both cases:
Subject: [PATCH] scsi: BUG_ON() impossible condition.
If blk_rq_map_sg wrote more than was allocated in the scatterlist, BUG_ON() is probably the right thing to do.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> --- drivers/scsi/scsi_tgt_lib.c | 11 +++-------- 1 files changed, 3 insertions(+), 8 deletions(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1102,7 +1102,6 @@ void scsi_io_completion(struct scsi_cmnd * * Returns: 0 on success * BLKPREP_DEFER if the failure is retryable - * BLKPREP_KILL if the failure is fatal */ static int scsi_init_io(struct scsi_cmnd *cmd) { @@ -1136,17 +1135,9 @@ static int scsi_init_io(struct scsi_cmnd * each segment. */ count = blk_rq_map_sg(req->q, req, cmd->request_buffer); - if (likely(count <= cmd->use_sg)) { - cmd->use_sg = count; - return BLKPREP_OK; - } - - printk(KERN_ERR "Incorrect number of segments after building list\n"); - printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg); - printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors, - req->current_nr_sectors); - - return BLKPREP_KILL; + BUG_ON(count > cmd->use_sg); + cmd->use_sg = count; + return BLKPREP_OK; } static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev, diff --git a/drivers/scsi/scsi_tgt_lib.c b/drivers/scsi/scsi_tgt_lib.c --- a/drivers/scsi/scsi_tgt_lib.c +++ b/drivers/scsi/scsi_tgt_lib.c @@ -367,14 +367,9 @@ static int scsi_tgt_init_cmd(struct scsi dprintk("cmd %p cnt %d %lu\n", cmd, cmd->use_sg, rq_data_dir(rq)); count = blk_rq_map_sg(rq->q, rq, cmd->request_buffer); - if (likely(count <= cmd->use_sg)) { - cmd->use_sg = count; - return 0; - } - - eprintk("cmd %p cnt %d\n", cmd, cmd->use_sg); - scsi_free_sgtable(cmd); - return -EINVAL; + BUG_ON(count > cmd->use_sg); + cmd->use_sg = count; + return 0; } /* TODO: test this crap and replace bio_map_user with new interface maybe */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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