Commit 65ca846a authored by Bart Van Assche's avatar Bart Van Assche Committed by Martin K. Petersen
Browse files

scsi: core: Introduce {init,exit}_cmd_priv() 

The current behavior of the SCSI core is to clear driver-private data
before preparing a request for submission to the SCSI LLD. Make it possible
for SCSI LLDs to disable clearing of driver-private data.

These hooks will be used by a later patch, namely "scsi: ufs: Let the SCSI
core allocate per-command UFS data".

Link: https://lore.kernel.org/r/20200123035637.21848-2-bvanassche@acm.org


Cc: Tomas Winkler <tomas.winkler@intel.com>
Cc: Stanley Chu <stanley.chu@mediatek.com>
Cc: Bean Huo <beanhuo@micron.com>
Cc: Avri Altman <avri.altman@wdc.com>
Cc: Can Guo <cang@codeaurora.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Johannes Thumshirn <jth@kernel.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent c5a97076

drivers/scsi/scsi_lib.c

+23 −6
Original line number Diff line number Diff line
@@ -1097,7 +1097,7 @@ static void scsi_cleanup_rq(struct request *rq) 
	}

}



/* Called after a request has been started. */

/* Called before a request is prepared. See also scsi_mq_prep_fn(). */

void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)

{

	void *buf = cmd->sense_buffer;
@@ -1105,7 +1105,7 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd) 
	struct request *rq = blk_mq_rq_from_pdu(cmd);

	unsigned int flags = cmd->flags & SCMD_PRESERVED_FLAGS;

	unsigned long jiffies_at_alloc;

	int retries;

	int retries, to_clear;

	bool in_flight;



	if (!blk_rq_is_scsi(rq) && !(flags & SCMD_INITIALIZED)) {
@@ -1116,9 +1116,15 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd) 
	jiffies_at_alloc = cmd->jiffies_at_alloc;

	retries = cmd->retries;

	in_flight = test_bit(SCMD_STATE_INFLIGHT, &cmd->state);

	/* zero out the cmd, except for the embedded scsi_request */

	memset((char *)cmd + sizeof(cmd->req), 0,

		sizeof(*cmd) - sizeof(cmd->req) + dev->host->hostt->cmd_size);

	/*

	 * Zero out the cmd, except for the embedded scsi_request. Only clear

	 * the driver-private command data if the LLD does not supply a

	 * function to initialize that data.

	 */

	to_clear = sizeof(*cmd) - sizeof(cmd->req);

	if (!dev->host->hostt->init_cmd_priv)

		to_clear += dev->host->hostt->cmd_size;

	memset((char *)cmd + sizeof(cmd->req), 0, to_clear);



	cmd->device = dev;

	cmd->sense_buffer = buf;
@@ -1711,6 +1717,7 @@ static int scsi_mq_init_request(struct blk_mq_tag_set *set, struct request *rq, 
	const bool unchecked_isa_dma = shost->unchecked_isa_dma;

	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);

	struct scatterlist *sg;

	int ret = 0;



	if (unchecked_isa_dma)

		cmd->flags |= SCMD_UNCHECKED_ISA_DMA;
@@ -1726,14 +1733,24 @@ static int scsi_mq_init_request(struct blk_mq_tag_set *set, struct request *rq, 
		cmd->prot_sdb = (void *)sg + scsi_mq_inline_sgl_size(shost);

	}



	return 0;

	if (shost->hostt->init_cmd_priv) {

		ret = shost->hostt->init_cmd_priv(shost, cmd);

		if (ret < 0)

			scsi_free_sense_buffer(unchecked_isa_dma,

					       cmd->sense_buffer);

	}



	return ret;

}



static void scsi_mq_exit_request(struct blk_mq_tag_set *set, struct request *rq,

				 unsigned int hctx_idx)

{

	struct Scsi_Host *shost = set->driver_data;

	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);



	if (shost->hostt->exit_cmd_priv)

		shost->hostt->exit_cmd_priv(shost, cmd);

	scsi_free_sense_buffer(cmd->flags & SCMD_UNCHECKED_ISA_DMA,

			       cmd->sense_buffer);

}

include/scsi/scsi_host.h

+3 −0
Original line number Diff line number Diff line
@@ -62,6 +62,9 @@ struct scsi_host_template { 
			    void __user *arg);

#endif



	int (*init_cmd_priv)(struct Scsi_Host *shost, struct scsi_cmnd *cmd);

	int (*exit_cmd_priv)(struct Scsi_Host *shost, struct scsi_cmnd *cmd);



	/*

	 * The queuecommand function is used to queue up a scsi

	 * command block to the LLDD.  When the driver finished

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