diff options
| -rw-r--r-- | drivers/scsi/sg.c | 79 |
1 files changed, 41 insertions, 38 deletions
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index df5e961484e1..4efa9b5884b7 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -170,11 +170,11 @@ typedef struct sg_fd { /* holds the state of a file descriptor */ typedef struct sg_device { /* holds the state of each scsi generic device */ struct scsi_device *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; + struct rw_semaphore o_sem; /* exclude open should hold this rwsem */ volatile char detached; /* 0->attached, 1->detached pending removal */ /* exclude protected by sg_open_exclusive_lock */ char exclude; /* opened for exclusive access */ @@ -265,7 +265,6 @@ sg_open(struct inode *inode, struct file *filp) struct request_queue *q; Sg_device *sdp; Sg_fd *sfp; - int res; int retval; nonseekable_open(inode, filp); @@ -294,35 +293,35 @@ sg_open(struct inode *inode, struct file *filp) goto error_out; } - if (flags & O_EXCL) { - if (O_RDONLY == (flags & O_ACCMODE)) { - retval = -EPERM; /* Can't lock it with read only access */ - goto error_out; - } - if (!sfds_list_empty(sdp) && (flags & O_NONBLOCK)) { - retval = -EBUSY; - goto error_out; - } - res = wait_event_interruptible(sdp->o_excl_wait, - ((!sfds_list_empty(sdp) || get_exclude(sdp)) ? 0 : set_exclude(sdp, 1))); - if (res) { - retval = res; /* -ERESTARTSYS because signal hit process */ - goto error_out; - } - } else if (get_exclude(sdp)) { /* some other fd has an exclusive lock on dev */ - if (flags & O_NONBLOCK) { - retval = -EBUSY; - goto error_out; - } - res = wait_event_interruptible(sdp->o_excl_wait, !get_exclude(sdp)); - if (res) { - retval = res; /* -ERESTARTSYS because signal hit process */ - goto error_out; + if ((flags & O_EXCL) && (O_RDONLY == (flags & O_ACCMODE))) { + retval = -EPERM; /* Can't lock it with read only access */ + goto error_out; + } + if (flags & O_NONBLOCK) { + if (flags & O_EXCL) { + if (!down_write_trylock(&sdp->o_sem)) { + retval = -EBUSY; + goto error_out; + } + } else { + if (!down_read_trylock(&sdp->o_sem)) { + retval = -EBUSY; + goto error_out; + } } + } else { + if (flags & O_EXCL) + down_write(&sdp->o_sem); + else + down_read(&sdp->o_sem); } + /* Since write lock is held, no need to check sfd_list */ + if (flags & O_EXCL) + set_exclude(sdp, 1); + if (sdp->detached) { retval = -ENODEV; - goto error_out; + goto sem_out; } if (sfds_list_empty(sdp)) { /* no existing opens on this device */ sdp->sgdebug = 0; @@ -331,17 +330,18 @@ sg_open(struct inode *inode, struct file *filp) } if ((sfp = sg_add_sfp(sdp, dev))) filp->private_data = sfp; + /* retval is already provably zero at this point because of the + * check after retval = scsi_autopm_get_device(sdp->device)) + */ else { + retval = -ENOMEM; +sem_out: if (flags & O_EXCL) { set_exclude(sdp, 0); /* undo if error */ - wake_up_interruptible(&sdp->o_excl_wait); - } - retval = -ENOMEM; - goto error_out; - } - retval = 0; + up_write(&sdp->o_sem); + } else + up_read(&sdp->o_sem); error_out: - if (retval) { scsi_autopm_put_device(sdp->device); sdp_put: scsi_device_put(sdp->device); @@ -358,13 +358,18 @@ sg_release(struct inode *inode, struct file *filp) { Sg_device *sdp; Sg_fd *sfp; + int excl; if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp))) return -ENXIO; SCSI_LOG_TIMEOUT(3, printk("sg_release: %s\n", sdp->disk->disk_name)); + excl = get_exclude(sdp); set_exclude(sdp, 0); - wake_up_interruptible(&sdp->o_excl_wait); + if (excl) + up_write(&sdp->o_sem); + else + up_read(&sdp->o_sem); scsi_autopm_put_device(sdp->device); kref_put(&sfp->f_ref, sg_remove_sfp); @@ -1416,7 +1421,7 @@ static Sg_device *sg_alloc(struct gendisk *disk, struct scsi_device *scsidp) sdp->disk = disk; sdp->device = scsidp; INIT_LIST_HEAD(&sdp->sfds); - init_waitqueue_head(&sdp->o_excl_wait); + init_rwsem(&sdp->o_sem); sdp->sg_tablesize = queue_max_segments(q); sdp->index = k; kref_init(&sdp->d_ref); @@ -2127,13 +2132,11 @@ static void sg_remove_sfp_usercontext(struct work_struct *work) 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; unsigned long iflags; write_lock_irqsave(&sg_index_lock, iflags); list_del(&sfp->sfd_siblings); write_unlock_irqrestore(&sg_index_lock, iflags); - wake_up_interruptible(&sdp->o_excl_wait); INIT_WORK(&sfp->ew.work, sg_remove_sfp_usercontext); schedule_work(&sfp->ew.work); |