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[SCSI] sg: push file descriptor list locking down to per-device locking 

Push file descriptor list locking down to per-device locking. Let sg_index_lock
only protect device lookup.
sdp->detached is also set and checked with this lock held.

Signed-off-by: Vaughan Cao <vaughan.cao@oracle.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
This commit is contained in:
Vaughan Cao 2013-08-29 10:00:39 +08:00 committed by James Bottomley
parent e32c9e6300
commit 1f962ebcdf
1 changed files with 34 additions and 28 deletions
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62
drivers/scsi/sg.c
View File

@ -106,8 +106,7 @@ static int sg_add(struct device *, struct class_interface *);
static void sg_remove(struct device *, struct class_interface *); static void sg_remove(struct device *, struct class_interface *);
static DEFINE_IDR(sg_index_idr); static DEFINE_IDR(sg_index_idr);
static DEFINE_RWLOCK(sg_index_lock); /* Also used to lock static DEFINE_RWLOCK(sg_index_lock);
file descriptor list for device */
static struct class_interface sg_interface = { static struct class_interface sg_interface = {
.add_dev = sg_add, .add_dev = sg_add,
@ -144,8 +143,7 @@ typedef struct sg_request { /* SG_MAX_QUEUE requests outstanding per file */
} Sg_request; } Sg_request;
typedef struct sg_fd { /* holds the state of a file descriptor */ typedef struct sg_fd { /* holds the state of a file descriptor */
/* sfd_siblings is protected by sg_index_lock */ struct list_head sfd_siblings; /* protected by sfd_lock of device */
struct list_head sfd_siblings;
struct sg_device *parentdp; /* owning device */ struct sg_device *parentdp; /* owning device */
wait_queue_head_t read_wait; /* queue read until command done */ wait_queue_head_t read_wait; /* queue read until command done */
rwlock_t rq_list_lock; /* protect access to list in req_arr */ rwlock_t rq_list_lock; /* protect access to list in req_arr */
@ -170,7 +168,7 @@ typedef struct sg_device { /* holds the state of each scsi generic device */
struct scsi_device *device; struct scsi_device *device;
int sg_tablesize; /* adapter's max scatter-gather table size */ int sg_tablesize; /* adapter's max scatter-gather table size */
u32 index; /* device index number */ u32 index; /* device index number */
/* sfds is protected by sg_index_lock */ spinlock_t sfd_lock; /* protect file descriptor list for device */
struct list_head sfds; struct list_head sfds;
struct rw_semaphore o_sem; /* exclude open should hold this rwsem */ struct rw_semaphore o_sem; /* exclude open should hold this rwsem */
volatile char detached; /* 0->attached, 1->detached pending removal */ volatile char detached; /* 0->attached, 1->detached pending removal */
@ -227,9 +225,9 @@ static int sfds_list_empty(Sg_device *sdp)
unsigned long flags; unsigned long flags;
int ret; int ret;
read_lock_irqsave(&sg_index_lock, flags); spin_lock_irqsave(&sdp->sfd_lock, flags);
ret = list_empty(&sdp->sfds); ret = list_empty(&sdp->sfds);
read_unlock_irqrestore(&sg_index_lock, flags); spin_unlock_irqrestore(&sdp->sfd_lock, flags);
return ret; return ret;
} }
@ -1393,6 +1391,7 @@ static Sg_device *sg_alloc(struct gendisk *disk, struct scsi_device *scsidp)
disk->first_minor = k; disk->first_minor = k;
sdp->disk = disk; sdp->disk = disk;
sdp->device = scsidp; sdp->device = scsidp;
spin_lock_init(&sdp->sfd_lock);
INIT_LIST_HEAD(&sdp->sfds); INIT_LIST_HEAD(&sdp->sfds);
init_rwsem(&sdp->o_sem); init_rwsem(&sdp->o_sem);
sdp->sg_tablesize = queue_max_segments(q); sdp->sg_tablesize = queue_max_segments(q);
@ -1527,11 +1526,13 @@ static void sg_remove(struct device *cl_dev, struct class_interface *cl_intf)
/* Need a write lock to set sdp->detached. */ /* Need a write lock to set sdp->detached. */
write_lock_irqsave(&sg_index_lock, iflags); write_lock_irqsave(&sg_index_lock, iflags);
spin_lock(&sdp->sfd_lock);
sdp->detached = 1; sdp->detached = 1;
list_for_each_entry(sfp, &sdp->sfds, sfd_siblings) { list_for_each_entry(sfp, &sdp->sfds, sfd_siblings) {
wake_up_interruptible(&sfp->read_wait); wake_up_interruptible(&sfp->read_wait);
kill_fasync(&sfp->async_qp, SIGPOLL, POLL_HUP); kill_fasync(&sfp->async_qp, SIGPOLL, POLL_HUP);
} }
spin_unlock(&sdp->sfd_lock);
write_unlock_irqrestore(&sg_index_lock, iflags); write_unlock_irqrestore(&sg_index_lock, iflags);
sysfs_remove_link(&scsidp->sdev_gendev.kobj, "generic"); sysfs_remove_link(&scsidp->sdev_gendev.kobj, "generic");
@ -2056,13 +2057,13 @@ sg_add_sfp(Sg_device * sdp, int dev)
sfp->cmd_q = SG_DEF_COMMAND_Q; sfp->cmd_q = SG_DEF_COMMAND_Q;
sfp->keep_orphan = SG_DEF_KEEP_ORPHAN; sfp->keep_orphan = SG_DEF_KEEP_ORPHAN;
sfp->parentdp = sdp; sfp->parentdp = sdp;
write_lock_irqsave(&sg_index_lock, iflags); spin_lock_irqsave(&sdp->sfd_lock, iflags);
if (sdp->detached) { if (sdp->detached) {
write_unlock_irqrestore(&sg_index_lock, iflags); spin_unlock_irqrestore(&sdp->sfd_lock, iflags);
return ERR_PTR(-ENODEV); return ERR_PTR(-ENODEV);
} }
list_add_tail(&sfp->sfd_siblings, &sdp->sfds); list_add_tail(&sfp->sfd_siblings, &sdp->sfds);
write_unlock_irqrestore(&sg_index_lock, iflags); spin_unlock_irqrestore(&sdp->sfd_lock, iflags);
SCSI_LOG_TIMEOUT(3, printk("sg_add_sfp: sfp=0x%p\n", sfp)); SCSI_LOG_TIMEOUT(3, printk("sg_add_sfp: sfp=0x%p\n", sfp));
if (unlikely(sg_big_buff != def_reserved_size)) if (unlikely(sg_big_buff != def_reserved_size))
sg_big_buff = def_reserved_size; sg_big_buff = def_reserved_size;
@ -2109,11 +2110,12 @@ static void sg_remove_sfp_usercontext(struct work_struct *work)
static void sg_remove_sfp(struct kref *kref) static void sg_remove_sfp(struct kref *kref)
{ {
struct sg_fd *sfp = container_of(kref, struct sg_fd, f_ref); struct sg_fd *sfp = container_of(kref, struct sg_fd, f_ref);
struct sg_device *sdp = sfp->parentdp;
unsigned long iflags; unsigned long iflags;
write_lock_irqsave(&sg_index_lock, iflags); spin_lock_irqsave(&sdp->sfd_lock, iflags);
list_del(&sfp->sfd_siblings); list_del(&sfp->sfd_siblings);
write_unlock_irqrestore(&sg_index_lock, iflags); spin_unlock_irqrestore(&sdp->sfd_lock, iflags);
INIT_WORK(&sfp->ew.work, sg_remove_sfp_usercontext); INIT_WORK(&sfp->ew.work, sg_remove_sfp_usercontext);
schedule_work(&sfp->ew.work); schedule_work(&sfp->ew.work);
@ -2500,7 +2502,7 @@ static int sg_proc_seq_show_devstrs(struct seq_file *s, void *v)
return 0; return 0;
} }
/* must be called while holding sg_index_lock */ /* must be called while holding sg_index_lock and sfd_lock */
static void sg_proc_debug_helper(struct seq_file *s, Sg_device * sdp) static void sg_proc_debug_helper(struct seq_file *s, Sg_device * sdp)
{ {
int k, m, new_interface, blen, usg; int k, m, new_interface, blen, usg;
@ -2585,22 +2587,26 @@ static int sg_proc_seq_show_debug(struct seq_file *s, void *v)
read_lock_irqsave(&sg_index_lock, iflags); read_lock_irqsave(&sg_index_lock, iflags);
sdp = it ? sg_lookup_dev(it->index) : NULL; sdp = it ? sg_lookup_dev(it->index) : NULL;
if (sdp && !list_empty(&sdp->sfds)) { if (sdp) {
struct scsi_device *scsidp = sdp->device; spin_lock(&sdp->sfd_lock);
if (!list_empty(&sdp->sfds)) {
struct scsi_device *scsidp = sdp->device;
seq_printf(s, " >>> device=%s ", sdp->disk->disk_name); seq_printf(s, " >>> device=%s ", sdp->disk->disk_name);
if (sdp->detached) if (sdp->detached)
seq_printf(s, "detached pending close "); seq_printf(s, "detached pending close ");
else else
seq_printf seq_printf
(s, "scsi%d chan=%d id=%d lun=%d em=%d", (s, "scsi%d chan=%d id=%d lun=%d em=%d",
scsidp->host->host_no, scsidp->host->host_no,
scsidp->channel, scsidp->id, scsidp->channel, scsidp->id,
scsidp->lun, scsidp->lun,
scsidp->host->hostt->emulated); scsidp->host->hostt->emulated);
seq_printf(s, " sg_tablesize=%d excl=%d\n", seq_printf(s, " sg_tablesize=%d excl=%d\n",
sdp->sg_tablesize, sdp->exclude); sdp->sg_tablesize, sdp->exclude);
sg_proc_debug_helper(s, sdp); sg_proc_debug_helper(s, sdp);
}
spin_unlock(&sdp->sfd_lock);
} }
read_unlock_irqrestore(&sg_index_lock, iflags); read_unlock_irqrestore(&sg_index_lock, iflags);
return 0; return 0;