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Commit b75ca5ea authored by Stefan Richter's avatar Stefan Richter
Browse files

firewire: sbp2: omit Scsi_Host lock from queuecommand 



firewire-sbp2 already takes care for internal serialization where
required (ORB list accesses), and it does not use cmd->serial_number
internally.  Hence it is safe to not grab the shost lock around
queuecommand.

While we are at housekeeping, drop a redundant struct member:
sbp2_command_orb.done is set once in a hot path and dereferenced once in
a hot path.  We can as well dereference sbp2_command_orb.cmd->scsi_done
instead.

Signed-off-by: default avatarStefan Richter <stefanr@s5r6.in-berlin.de>
parent 6ea9e7bb

drivers/firewire/sbp2.c

+6 −14
Original line number Diff line number Diff line
@@ -125,9 +125,6 @@ MODULE_PARM_DESC(workarounds, "Work around device bugs (default = 0" 
	", override internal blacklist = " __stringify(SBP2_WORKAROUND_OVERRIDE)

	", or a combination)");



/* I don't know why the SCSI stack doesn't define something like this... */

typedef void (*scsi_done_fn_t)(struct scsi_cmnd *);



static const char sbp2_driver_name[] = "sbp2";



/*
@@ -314,7 +311,6 @@ struct sbp2_command_orb { 
		u8 command_block[SBP2_MAX_CDB_SIZE];

	} request;

	struct scsi_cmnd *cmd;

	scsi_done_fn_t done;

	struct sbp2_logical_unit *lu;



	struct sbp2_pointer page_table[SG_ALL] __attribute__((aligned(8)));
@@ -1398,7 +1394,7 @@ static void complete_command_orb(struct sbp2_orb *base_orb, 
	sbp2_unmap_scatterlist(device->card->device, orb);



	orb->cmd->result = result;

	orb->done(orb->cmd);

	orb->cmd->scsi_done(orb->cmd);

}



static int sbp2_map_scatterlist(struct sbp2_command_orb *orb,
@@ -1463,7 +1459,8 @@ static int sbp2_map_scatterlist(struct sbp2_command_orb *orb, 


/* SCSI stack integration */



static int sbp2_scsi_queuecommand_lck(struct scsi_cmnd *cmd, scsi_done_fn_t done)

static int sbp2_scsi_queuecommand(struct Scsi_Host *shost,

				  struct scsi_cmnd *cmd)

{

	struct sbp2_logical_unit *lu = cmd->device->hostdata;

	struct fw_device *device = target_device(lu->tgt);
@@ -1477,7 +1474,7 @@ static int sbp2_scsi_queuecommand_lck(struct scsi_cmnd *cmd, scsi_done_fn_t done 
	if (cmd->sc_data_direction == DMA_BIDIRECTIONAL) {

		fw_error("Can't handle DMA_BIDIRECTIONAL, rejecting command\n");

		cmd->result = DID_ERROR << 16;

		done(cmd);

		cmd->scsi_done(cmd);

		return 0;

	}
@@ -1490,11 +1487,8 @@ static int sbp2_scsi_queuecommand_lck(struct scsi_cmnd *cmd, scsi_done_fn_t done 
	/* Initialize rcode to something not RCODE_COMPLETE. */

	orb->base.rcode = -1;

	kref_init(&orb->base.kref);



	orb->lu = lu;

	orb->done = done;

	orb->cmd = cmd;



	orb->request.next.high = cpu_to_be32(SBP2_ORB_NULL);

	orb->request.misc = cpu_to_be32(

		COMMAND_ORB_MAX_PAYLOAD(lu->tgt->max_payload) |
@@ -1529,8 +1523,6 @@ static int sbp2_scsi_queuecommand_lck(struct scsi_cmnd *cmd, scsi_done_fn_t done 
	return retval;

}



static DEF_SCSI_QCMD(sbp2_scsi_queuecommand)



static int sbp2_scsi_slave_alloc(struct scsi_device *sdev)

{

	struct sbp2_logical_unit *lu = sdev->hostdata;