Commit 4045de89 authored by Bart Van Assche's avatar Bart Van Assche Committed by Martin K. Petersen
Browse files

scsi: sg: Enable runtime power management 



In 2010, runtime power management support was implemented in the SCSI
core.  The description of patch "[SCSI] implement runtime Power
Management" mentions that the sg driver is skipped but not why. This
patch enables runtime power management even if an instance of the sg
driver is held open.  Enabling runtime PM for the sg driver is safe
because all interactions of the sg driver with the SCSI device pass
through the block layer (blk_execute_rq_nowait()) and the block layer
already supports runtime PM.

Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Fixes: bc4f2401 ("[SCSI] implement runtime Power Management")
Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20241030220310.1373569-1-bvanassche@acm.org


Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 95bbdca4

drivers/scsi/sg.c

+1 −8
Original line number Diff line number Diff line
@@ -307,10 +307,6 @@ sg_open(struct inode *inode, struct file *filp) 
	if (retval)

		goto sg_put;



	retval = scsi_autopm_get_device(device);

	if (retval)

		goto sdp_put;



	/* scsi_block_when_processing_errors() may block so bypass

	 * check if O_NONBLOCK. Permits SCSI commands to be issued

	 * during error recovery. Tread carefully. */
@@ -318,7 +314,7 @@ sg_open(struct inode *inode, struct file *filp) 
	      scsi_block_when_processing_errors(device))) {

		retval = -ENXIO;

		/* we are in error recovery for this device */

		goto error_out;

		goto sdp_put;

	}



	mutex_lock(&sdp->open_rel_lock);
@@ -371,8 +367,6 @@ sg_open(struct inode *inode, struct file *filp) 
	}

error_mutex_locked:

	mutex_unlock(&sdp->open_rel_lock);

error_out:

	scsi_autopm_put_device(device);

sdp_put:

	kref_put(&sdp->d_ref, sg_device_destroy);

	scsi_device_put(device);
@@ -392,7 +386,6 @@ sg_release(struct inode *inode, struct file *filp) 
	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp, "sg_release\n"));



	mutex_lock(&sdp->open_rel_lock);

	scsi_autopm_put_device(sdp->device);

	kref_put(&sfp->f_ref, sg_remove_sfp);

	sdp->open_cnt--;