* [PATCH 2/2] scsi: remove scsi_end_request
2014-03-12 11:06 [PATCH 1/2] scsi: explicitly release bidi buffers Christoph Hellwig
@ 2014-03-12 11:07 ` Christoph Hellwig
2014-03-26 9:46 ` [PATCH 1/2] scsi: explicitly release bidi buffers Christoph Hellwig
1 sibling, 0 replies; 3+ messages in thread
From: Christoph Hellwig @ 2014-03-12 11:07 UTC (permalink / raw)
To: James Bottomley; +Cc: linux-scsi
By folding scsi_end_request into its only caller we can significantly clean
up the completion logic. We can use simple goto labels now to only have
a single place to finish or requeue command there instead of the previous
convoluted logic.
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 3012700..0bcb7c4 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -511,66 +511,6 @@ void scsi_run_host_queues(struct Scsi_Host *shost)
scsi_run_queue(sdev->request_queue);
}
-/*
- * Function: scsi_end_request()
- *
- * Purpose: Post-processing of completed commands (usually invoked at end
- * of upper level post-processing and scsi_io_completion).
- *
- * Arguments: cmd - command that is complete.
- * error - 0 if I/O indicates success, < 0 for I/O error.
- * bytes - number of bytes of completed I/O
- * requeue - indicates whether we should requeue leftovers.
- *
- * Lock status: Assumed that lock is not held upon entry.
- *
- * Returns: cmd if requeue required, NULL otherwise.
- *
- * Notes: This is called for block device requests in order to
- * mark some number of sectors as complete.
- *
- * We are guaranteeing that the request queue will be goosed
- * at some point during this call.
- * Notes: If cmd was requeued, upon return it will be a stale pointer.
- */
-static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
- int bytes, int requeue)
-{
- struct request_queue *q = cmd->device->request_queue;
- struct request *req = cmd->request;
-
- /*
- * If there are blocks left over at the end, set up the command
- * to queue the remainder of them.
- */
- if (blk_end_request(req, error, bytes)) {
- /* kill remainder if no retrys */
- if (error && scsi_noretry_cmd(cmd))
- blk_end_request_all(req, error);
- else {
- if (requeue) {
- /*
- * Bleah. Leftovers again. Stick the
- * leftovers in the front of the
- * queue, and goose the queue again.
- */
- scsi_release_buffers(cmd);
- scsi_requeue_command(q, cmd);
- cmd = NULL;
- }
- return cmd;
- }
- }
-
- /*
- * This will goose the queue request function at the end, so we don't
- * need to worry about launching another command.
- */
- scsi_release_buffers(cmd);
- scsi_next_command(cmd);
- return NULL;
-}
-
static inline unsigned int scsi_sgtable_index(unsigned short nents)
{
unsigned int index;
@@ -716,16 +656,9 @@ static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
*
* Returns: Nothing
*
- * Notes: This function is matched in terms of capabilities to
- * the function that created the scatter-gather list.
- * In other words, if there are no bounce buffers
- * (the normal case for most drivers), we don't need
- * the logic to deal with cleaning up afterwards.
- *
- * We must call scsi_end_request(). This will finish off
- * the specified number of sectors. If we are done, the
- * command block will be released and the queue function
- * will be goosed. If we are not done then we have to
+ * Notes: We will finish off the specified number of sectors. If we
+ * are done, the command block will be released and the queue
+ * function will be goosed. If we are not done then we have to
* figure out what to do next:
*
* a) We can call scsi_requeue_command(). The request
@@ -734,7 +667,7 @@ static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
* be used if we made forward progress, or if we want
* to switch from READ(10) to READ(6) for example.
*
- * b) We can call scsi_queue_insert(). The request will
+ * b) We can call __scsi_queue_insert(). The request will
* be put back on the queue and retried using the same
* command as before, possibly after a delay.
*
@@ -792,6 +725,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
scsi_release_buffers(cmd);
scsi_release_bidi_buffers(cmd);
+
blk_end_request_all(req, 0);
scsi_next_command(cmd);
@@ -831,12 +765,25 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
}
/*
- * A number of bytes were successfully read. If there
- * are leftovers and there is some kind of error
- * (result != 0), retry the rest.
+ * If we finished all bytes in the request we are done now.
*/
- if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL)
- return;
+ if (!blk_end_request(req, error, good_bytes))
+ goto next_command;
+
+ /*
+ * Kill remainder if no retrys.
+ */
+ if (error && scsi_noretry_cmd(cmd)) {
+ blk_end_request_all(req, error);
+ goto next_command;
+ }
+
+ /*
+ * If there had been no error, but we have leftover bytes in the
+ * requeues just queue the command up again.
+ */
+ if (result == 0)
+ goto requeue;
error = __scsi_error_from_host_byte(cmd, result);
@@ -958,7 +905,6 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
switch (action) {
case ACTION_FAIL:
/* Give up and fail the remainder of the request */
- scsi_release_buffers(cmd);
if (!(req->cmd_flags & REQ_QUIET)) {
if (description)
scmd_printk(KERN_INFO, cmd, "%s\n",
@@ -968,12 +914,11 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
scsi_print_sense("", cmd);
scsi_print_command(cmd);
}
- if (blk_end_request_err(req, error))
- scsi_requeue_command(q, cmd);
- else
- scsi_next_command(cmd);
- break;
+ if (!blk_end_request_err(req, error))
+ goto next_command;
+ /*FALLTHRU*/
case ACTION_REPREP:
+ requeue:
/* Unprep the request and put it back at the head of the queue.
* A new command will be prepared and issued.
*/
@@ -989,6 +934,11 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
__scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
break;
}
+ return;
+
+next_command:
+ scsi_release_buffers(cmd);
+ scsi_next_command(cmd);
}
static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH 1/2] scsi: explicitly release bidi buffers
2014-03-12 11:06 [PATCH 1/2] scsi: explicitly release bidi buffers Christoph Hellwig
2014-03-12 11:07 ` [PATCH 2/2] scsi: remove scsi_end_request Christoph Hellwig
@ 2014-03-26 9:46 ` Christoph Hellwig
1 sibling, 0 replies; 3+ messages in thread
From: Christoph Hellwig @ 2014-03-26 9:46 UTC (permalink / raw)
To: James Bottomley; +Cc: linux-scsi
Now that LSF is done can I get anyone excited to review these?
On Wed, Mar 12, 2014 at 04:06:06AM -0700, Christoph Hellwig wrote:
> Instead of trying to guess when we have a BIDI buffer in scsi_release_buffers
> add a function to explicitly free the BIDI ressoures in the one place that
> handles them. This avoids needing a special __scsi_release_buffers for the
> case where we already have freed the request as well.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
>
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index debe30a..3012700 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -511,8 +511,6 @@ void scsi_run_host_queues(struct Scsi_Host *shost)
> scsi_run_queue(sdev->request_queue);
> }
>
> -static void __scsi_release_buffers(struct scsi_cmnd *, int);
> -
> /*
> * Function: scsi_end_request()
> *
> @@ -568,7 +566,7 @@ static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
> * This will goose the queue request function at the end, so we don't
> * need to worry about launching another command.
> */
> - __scsi_release_buffers(cmd, 0);
> + scsi_release_buffers(cmd);
> scsi_next_command(cmd);
> return NULL;
> }
> @@ -624,30 +622,10 @@ static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
> __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);
> }
>
> -static void __scsi_release_buffers(struct scsi_cmnd *cmd, int do_bidi_check)
> -{
> -
> - if (cmd->sdb.table.nents)
> - scsi_free_sgtable(&cmd->sdb);
> -
> - memset(&cmd->sdb, 0, sizeof(cmd->sdb));
> -
> - if (do_bidi_check && scsi_bidi_cmnd(cmd)) {
> - struct scsi_data_buffer *bidi_sdb =
> - cmd->request->next_rq->special;
> - scsi_free_sgtable(bidi_sdb);
> - kmem_cache_free(scsi_sdb_cache, bidi_sdb);
> - cmd->request->next_rq->special = NULL;
> - }
> -
> - if (scsi_prot_sg_count(cmd))
> - scsi_free_sgtable(cmd->prot_sdb);
> -}
> -
> /*
> * Function: scsi_release_buffers()
> *
> - * Purpose: Completion processing for block device I/O requests.
> + * Purpose: Free resources allocate for a scsi_command.
> *
> * Arguments: cmd - command that we are bailing.
> *
> @@ -658,15 +636,29 @@ static void __scsi_release_buffers(struct scsi_cmnd *cmd, int do_bidi_check)
> * Notes: In the event that an upper level driver rejects a
> * command, we must release resources allocated during
> * the __init_io() function. Primarily this would involve
> - * the scatter-gather table, and potentially any bounce
> - * buffers.
> + * the scatter-gather table.
> */
> void scsi_release_buffers(struct scsi_cmnd *cmd)
> {
> - __scsi_release_buffers(cmd, 1);
> + if (cmd->sdb.table.nents)
> + scsi_free_sgtable(&cmd->sdb);
> +
> + memset(&cmd->sdb, 0, sizeof(cmd->sdb));
> +
> + if (scsi_prot_sg_count(cmd))
> + scsi_free_sgtable(cmd->prot_sdb);
> }
> EXPORT_SYMBOL(scsi_release_buffers);
>
> +static void scsi_release_bidi_buffers(struct scsi_cmnd *cmd)
> +{
> + struct scsi_data_buffer *bidi_sdb = cmd->request->next_rq->special;
> +
> + scsi_free_sgtable(bidi_sdb);
> + kmem_cache_free(scsi_sdb_cache, bidi_sdb);
> + cmd->request->next_rq->special = NULL;
> +}
> +
> /**
> * __scsi_error_from_host_byte - translate SCSI error code into errno
> * @cmd: SCSI command (unused)
> @@ -799,6 +791,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
> req->next_rq->resid_len = scsi_in(cmd)->resid;
>
> scsi_release_buffers(cmd);
> + scsi_release_bidi_buffers(cmd);
> blk_end_request_all(req, 0);
>
> scsi_next_command(cmd);
> --
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---end quoted text---
^ permalink raw reply [flat|nested] 3+ messages in thread