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Commit 035d12e6 authored by Jörn Engel's avatar Jörn Engel Committed by James Bottomley
Browse files

[SCSI] sg: completely protect sfds 



sfds is protected by sg_index_lock - except for sg_open(), where it
isn't.  Change that and add some documentation.

Signed-off-by: default avatarJoern Engel <joern@logfs.org>
Acked-by: default avatarDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
parent b499e524

drivers/scsi/sg.c

+16 −3
Original line number Diff line number Diff line
@@ -146,6 +146,7 @@ typedef struct sg_request { /* SG_MAX_QUEUE requests outstanding per file */ 
} Sg_request;



typedef struct sg_fd {		/* holds the state of a file descriptor */

	/* sfd_siblings is protected by sg_index_lock */

	struct list_head sfd_siblings;

	struct sg_device *parentdp;	/* owning device */

	wait_queue_head_t read_wait;	/* queue read until command done */
@@ -172,6 +173,7 @@ typedef struct sg_device { /* holds the state of each scsi generic device */ 
	wait_queue_head_t o_excl_wait;	/* queue open() when O_EXCL in use */

	int sg_tablesize;	/* adapter's max scatter-gather table size */

	u32 index;		/* device index number */

	/* sfds is protected by sg_index_lock */

	struct list_head sfds;

	volatile char detached;	/* 0->attached, 1->detached pending removal */

	/* exclude protected by sg_open_exclusive_lock */
@@ -244,6 +246,17 @@ static int set_exclude(Sg_device *sdp, char val) 
	return val;

}



static int sfds_list_empty(Sg_device *sdp)

{

	unsigned long flags;

	int ret;



	read_lock_irqsave(&sg_index_lock, flags);

	ret = list_empty(&sdp->sfds);

	read_unlock_irqrestore(&sg_index_lock, flags);

	return ret;

}



static int

sg_open(struct inode *inode, struct file *filp)

{
@@ -287,12 +300,12 @@ sg_open(struct inode *inode, struct file *filp) 
			retval = -EPERM; /* Can't lock it with read only access */

			goto error_out;

		}

		if (!list_empty(&sdp->sfds) && (flags & O_NONBLOCK)) {

		if (!sfds_list_empty(sdp) && (flags & O_NONBLOCK)) {

			retval = -EBUSY;

			goto error_out;

		}

		res = wait_event_interruptible(sdp->o_excl_wait,

					   ((!list_empty(&sdp->sfds) || get_exclude(sdp)) ? 0 : set_exclude(sdp, 1)));

					   ((!sfds_list_empty(sdp) || get_exclude(sdp)) ? 0 : set_exclude(sdp, 1)));

		if (res) {

			retval = res;	/* -ERESTARTSYS because signal hit process */

			goto error_out;
@@ -312,7 +325,7 @@ sg_open(struct inode *inode, struct file *filp) 
		retval = -ENODEV;

		goto error_out;

	}

	if (list_empty(&sdp->sfds)) {	/* no existing opens on this device */

	if (sfds_list_empty(sdp)) {	/* no existing opens on this device */

		sdp->sgdebug = 0;

		q = sdp->device->request_queue;

		sdp->sg_tablesize = queue_max_segments(q);