ChangeLog:
- convert 3 BUG calls to WARN calls
- un-invert some conditional logic to uncover the real fast path
- try to improve the comments, including noting what the bool return
value from scsi_end_request() means
Signed-off-by: Douglas Gilbert <dgilb...@interlog.com>
---
drivers/scsi/scsi_lib.c | 45 ++++++++++++++++++++++++++-------------------
1 file changed, 26 insertions(+), 19 deletions(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 8074d0a14391..9ebcf6f15d1d 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -650,6 +650,7 @@ static void scsi_release_bidi_buffers(struct scsi_cmnd *cmd)
cmd->request->next_rq->special = NULL;
}
+/* Returns false when no more bytes to process, true if there are more */
static bool scsi_end_request(struct request *req, blk_status_t error,
unsigned int bytes, unsigned int bidi_bytes)
{
@@ -1030,38 +1031,44 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned
int good_bytes)
*/
scsi_req(req->next_rq)->resid_len = scsi_in(cmd)->resid;
if (scsi_end_request(req, BLK_STS_OK, blk_rq_bytes(req),
- blk_rq_bytes(req->next_rq)))
- BUG();
+ blk_rq_bytes(req->next_rq)))
+ WARN(true, "Bidi command with remaining bytes");
return;
}
}
- /* no bidi support for !blk_rq_is_passthrough yet */
- BUG_ON(blk_bidi_rq(req));
+ /* no bidi support yet, other than in pass-through */
+ if (unlikely(blk_bidi_rq(req))) {
+ WARN_ONCE(true, "Only support bidi command in passthrough");
+ scmd_printk(KERN_ERR, cmd, "Killing bidi command\n");
+ if (scsi_end_request(req, BLK_STS_IOERR, blk_rq_bytes(req),
+ blk_rq_bytes(req->next_rq)))
+ WARN(true, "Bidi command with remaining bytes");
+ return;
+ }
- /*
- * Next deal with any sectors which we were able to correctly
- * handle.
- */
SCSI_LOG_HLCOMPLETE(1, scmd_printk(KERN_INFO, cmd,
"%u sectors total, %d bytes done.\n",
blk_rq_sectors(req), good_bytes));
/*
- * special case: failed zero length commands always need to
- * drop down into the retry code. Otherwise, if we finished
- * all bytes in the request we are done now.
+ * Next deal with any sectors which we were able to correctly
+ * handle. Fast path should return in this block.
*/
- if (unlikely(!(blk_stat && blk_rq_bytes(req) == 0) &&
- !scsi_end_request(req, blk_stat, good_bytes, 0)))
- return;
-
+ if (likely(blk_rq_bytes(req) > 0 || blk_stat == BLK_STS_OK)) {
+ if (likely(!scsi_end_request(req, blk_stat, good_bytes, 0)))
+ return; /* no bytes remaining */
+ }
/*
- * Kill remainder if no retrys.
+ * This leaves failed, zero length commands plus commands with
+ * some bytes remaining.
*/
+
+ /* Kill remainder if no retrys. */
if (unlikely(blk_stat && scsi_noretry_cmd(cmd))) {
if (scsi_end_request(req, blk_stat, blk_rq_bytes(req), 0))
- BUG();
+ WARN_ONCE(true,
+ "Bytes remaining after failed, no-retry command");
return;
}
@@ -1071,8 +1078,8 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned
int good_bytes)
*/
if (likely(result == 0)) {
/*
- * Fast path: Unprep the request and put it back at the head
- * of the queue. A new command will be prepared and issued.
+ * Unprep the request and put it back at the head of the
+ * queue. A new command will be prepared and issued.
* This block is the same as case ACTION_REPREP in
* scsi_io_completion_action() above.
*/
--
2.14.1
