diff options
| -rw-r--r-- | drivers/scsi/sg.c | 34 |
1 files changed, 29 insertions, 5 deletions
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index d4af13269e85..4efa9b5884b7 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -105,6 +105,8 @@ static int scatter_elem_sz_prev = SG_SCATTER_SZ; static int sg_add(struct device *, struct class_interface *); static void sg_remove(struct device *, struct class_interface *); +static DEFINE_SPINLOCK(sg_open_exclusive_lock); + static DEFINE_IDR(sg_index_idr); static DEFINE_RWLOCK(sg_index_lock); /* Also used to lock file descriptor list for device */ @@ -174,6 +176,7 @@ typedef struct sg_device { /* holds the state of each scsi generic device */ 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 */ char sgdebug; /* 0->off, 1->sense, 9->dump dev, 10-> all devs */ struct gendisk *disk; @@ -222,6 +225,27 @@ static int sg_allow_access(struct file *filp, unsigned char *cmd) return blk_verify_command(cmd, filp->f_mode & FMODE_WRITE); } +static int get_exclude(Sg_device *sdp) +{ + unsigned long flags; + int ret; + + spin_lock_irqsave(&sg_open_exclusive_lock, flags); + ret = sdp->exclude; + spin_unlock_irqrestore(&sg_open_exclusive_lock, flags); + return ret; +} + +static int set_exclude(Sg_device *sdp, char val) +{ + unsigned long flags; + + spin_lock_irqsave(&sg_open_exclusive_lock, flags); + sdp->exclude = val; + spin_unlock_irqrestore(&sg_open_exclusive_lock, flags); + return val; +} + static int sfds_list_empty(Sg_device *sdp) { unsigned long flags; @@ -293,7 +317,7 @@ sg_open(struct inode *inode, struct file *filp) } /* Since write lock is held, no need to check sfd_list */ if (flags & O_EXCL) - sdp->exclude = 1; /* used by release lock */ + set_exclude(sdp, 1); if (sdp->detached) { retval = -ENODEV; @@ -313,7 +337,7 @@ sg_open(struct inode *inode, struct file *filp) retval = -ENOMEM; sem_out: if (flags & O_EXCL) { - sdp->exclude = 0; /* undo if error */ + set_exclude(sdp, 0); /* undo if error */ up_write(&sdp->o_sem); } else up_read(&sdp->o_sem); @@ -340,8 +364,8 @@ sg_release(struct inode *inode, struct file *filp) return -ENXIO; SCSI_LOG_TIMEOUT(3, printk("sg_release: %s\n", sdp->disk->disk_name)); - excl = sdp->exclude; - sdp->exclude = 0; + excl = get_exclude(sdp); + set_exclude(sdp, 0); if (excl) up_write(&sdp->o_sem); else @@ -2598,7 +2622,7 @@ static int sg_proc_seq_show_debug(struct seq_file *s, void *v) scsidp->lun, scsidp->host->hostt->emulated); seq_printf(s, " sg_tablesize=%d excl=%d\n", - sdp->sg_tablesize, sdp->exclude); + sdp->sg_tablesize, get_exclude(sdp)); sg_proc_debug_helper(s, sdp); } read_unlock_irqrestore(&sg_index_lock, iflags); |