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path: root/drivers/scsi/sg.c
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Diffstat (limited to 'drivers/scsi/sg.c')
-rw-r--r--drivers/scsi/sg.c34
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);