[SCSI] sg: completely protect sfds (035d12e6) · Commits · 戴 / test

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);

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