[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>

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index d45ac4a..7bf54c9 100644 (file)
--- 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);