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

FUJITA Tomonori
2009-02-16T04:27:08Z

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>
---
drivers/scsi/sg.c | 50 ++++++++++++++------------------------------------
1 files changed, 14 insertions(+), 36 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index b459864..17d1bd5 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);
--
1.5.6.5