[SCSI] sg: remove the own list management for struct sg_fd

This replaces the own list management for struct sg_fd with the
standard list_head structure.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 14 insertions, 36 deletions

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index d45ac4aab92f..7bf54c9a33bb 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -140,7 +140,7 @@ typedef struct sg_request {	/* SG_MAX_QUEUE requests outstanding per file */
 } Sg_request;
 
 typedef struct sg_fd {          /* holds the state of a file descriptor */
-        struct sg_fd *nextfp;   /* NULL when last opened fd on this device */
+        struct list_head sfd_siblings;
         struct sg_device *parentdp;     /* owning device */
         wait_queue_head_t read_wait;    /* queue read until command done */
         rwlock_t rq_list_lock;  /* protect access to list in req_arr */
@@ -167,7 +167,7 @@ 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 */
-        Sg_fd *headfp;          /* first open fd belonging to this device */
+        struct list_head sfds;
         volatile char detached; /* 0->attached, 1->detached pending removal */
         volatile char exclude;  /* opened for exclusive access */
         char sgdebug;           /* 0->off, 1->sense, 9->dump dev, 10-> all devs */
@@ -258,13 +258,13 @@ sg_open(struct inode *inode, struct file *filp)
                         retval = -EPERM; /* Can't lock it with read only access */
                         goto error_out;
                 }
-                if (sdp->headfp && (flags & O_NONBLOCK)) {
+                if (!list_empty(&sdp->sfds) && (flags & O_NONBLOCK)) {
                         retval = -EBUSY;
                         goto error_out;
                 }
                 res = 0;
                 __wait_event_interruptible(sdp->o_excl_wait,
-                        ((sdp->headfp || sdp->exclude) ? 0 : (sdp->exclude = 1)), res);
+                                           ((!list_empty(&sdp->sfds) || sdp->exclude) ? 0 : (sdp->exclude = 1)), res);
                 if (res) {
                         retval = res;   /* -ERESTARTSYS because signal hit process */
                         goto error_out;
@@ -286,7 +286,7 @@ sg_open(struct inode *inode, struct file *filp)
                 retval = -ENODEV;
                 goto error_out;
         }
-        if (!sdp->headfp) {     /* no existing opens on this device */
+        if (list_empty(&sdp->sfds)) {   /* no existing opens on this device */
                 sdp->sgdebug = 0;
                 q = sdp->device->request_queue;
                 sdp->sg_tablesize = min(q->max_hw_segments,
@@ -1375,6 +1375,7 @@ static Sg_device *sg_alloc(struct gendisk *disk, struct scsi_device *scsidp)
         disk->first_minor = k;
         sdp->disk = disk;
         sdp->device = scsidp;
+        INIT_LIST_HEAD(&sdp->sfds);
         init_waitqueue_head(&sdp->o_excl_wait);
         sdp->sg_tablesize = min(q->max_hw_segments, q->max_phys_segments);
         sdp->index = k;
@@ -1517,7 +1518,7 @@ static void sg_remove(struct device *cl_dev, struct class_interface *cl_intf)
         /* Need a write lock to set sdp->detached. */
         write_lock_irqsave(&sg_index_lock, iflags);
         sdp->detached = 1;
-        for (sfp = sdp->headfp; sfp; sfp = sfp->nextfp) {
+        list_for_each_entry(sfp, &sdp->sfds, sfd_siblings) {
                 wake_up_interruptible(&sfp->read_wait);
                 kill_fasync(&sfp->async_qp, SIGPOLL, POLL_HUP);
         }
@@ -2024,14 +2025,7 @@ sg_add_sfp(Sg_device * sdp, int dev)
         sfp->keep_orphan = SG_DEF_KEEP_ORPHAN;
         sfp->parentdp = sdp;
         write_lock_irqsave(&sg_index_lock, iflags);
-        if (!sdp->headfp)
-                sdp->headfp = sfp;
-        else {                  /* add to tail of existing list */
-                Sg_fd *pfp = sdp->headfp;
-                while (pfp->nextfp)
-                        pfp = pfp->nextfp;
-                pfp->nextfp = sfp;
-        }
+        list_add_tail(&sfp->sfd_siblings, &sdp->sfds);
         write_unlock_irqrestore(&sg_index_lock, iflags);
         SCSI_LOG_TIMEOUT(3, printk("sg_add_sfp: sfp=0x%p\n", sfp));
         if (unlikely(sg_big_buff != def_reserved_size))
@@ -2080,28 +2074,10 @@ static void sg_remove_sfp(struct kref *kref)
 {
         struct sg_fd *sfp = container_of(kref, struct sg_fd, f_ref);
         struct sg_device *sdp = sfp->parentdp;
-        Sg_fd *fp;
-        Sg_fd *prev_fp;
         unsigned long iflags;
 
-        /* CAUTION!  Note that sfp can still be found by walking sdp->headfp
-         * even though the refcount is now 0.  Therefore, unlink sfp from
-         * sdp->headfp BEFORE doing any other cleanup.
-         */
-
         write_lock_irqsave(&sg_index_lock, iflags);
-        prev_fp = sdp->headfp;
-        if (sfp == prev_fp)
-                sdp->headfp = prev_fp->nextfp;
-        else {
-                while ((fp = prev_fp->nextfp)) {
-                        if (sfp == fp) {
-                                prev_fp->nextfp = fp->nextfp;
-                                break;
-                        }
-                        prev_fp = fp;
-                }
-        }
+        list_del(&sfp->sfd_siblings);
         write_unlock_irqrestore(&sg_index_lock, iflags);
         wake_up_interruptible(&sdp->o_excl_wait);
 
@@ -2486,10 +2462,12 @@ static void sg_proc_debug_helper(struct seq_file *s, Sg_device * sdp)
         const char * cp;
         unsigned int ms;
 
-        for (k = 0, fp = sdp->headfp; fp != NULL; ++k, fp = fp->nextfp) {
+        k = 0;
+        list_for_each_entry(fp, &sdp->sfds, sfd_siblings) {
+                k++;
                 read_lock(&fp->rq_list_lock); /* irqs already disabled */
                 seq_printf(s, "   FD(%d): timeout=%dms bufflen=%d "
-                           "(res)sgat=%d low_dma=%d\n", k + 1,
+                           "(res)sgat=%d low_dma=%d\n", k,
                            jiffies_to_msecs(fp->timeout),
                            fp->reserve.bufflen,
                            (int) fp->reserve.k_use_sg,
@@ -2559,7 +2537,7 @@ static int sg_proc_seq_show_debug(struct seq_file *s, void *v)
 
         read_lock_irqsave(&sg_index_lock, iflags);
         sdp = it ? sg_lookup_dev(it->index) : NULL;
-        if (sdp && sdp->headfp) {
+        if (sdp && !list_empty(&sdp->sfds)) {
                 struct scsi_device *scsidp = sdp->device;
 
                 seq_printf(s, " >>> device=%s ", sdp->disk->disk_name);