scsi/sd: remove big kernel lock

[net-next-2.6.git] / drivers / scsi / sd.c

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 01680c7c850728503bea1bf41f6658068f0f34cd..fc5d69a84af5ff66ca39fbed2e1496b3b6453f28 100644 (file)
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -783,6 +783,8 @@ static int sd_prep_fn(struct request_queue *q, struct request *rq)
  *     or from within the kernel (e.g. as a result of a mount(1) ).
  *     In the latter case @inode and @filp carry an abridged amount
  *     of information as noted above.
+ *
+ *     Locking: called with bdev->bd_mutex held.
  **/
 static int sd_open(struct block_device *bdev, fmode_t mode)
 {
@@ -795,7 +797,6 @@ static int sd_open(struct block_device *bdev, fmode_t mode)
 
        SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_open\n"));
 
-       lock_kernel();
        sdev = sdkp->device;
 
        /*
@@ -834,17 +835,15 @@ static int sd_open(struct block_device *bdev, fmode_t mode)
        if (!scsi_device_online(sdev))
                goto error_out;
 
-       if (!sdkp->openers++ && sdev->removable) {
+       if ((atomic_inc_return(&sdkp->openers) == 1) && sdev->removable) {
                if (scsi_block_when_processing_errors(sdev))
                        scsi_set_medium_removal(sdev, SCSI_REMOVAL_PREVENT);
        }
 
-       unlock_kernel();
        return 0;
 
 error_out:
        scsi_disk_put(sdkp);
-       unlock_kernel();
        return retval;  
 }
 
@@ -858,6 +857,8 @@ error_out:
  *
  *     Note: may block (uninterruptible) if error recovery is underway
  *     on this disk.
+ *
+ *     Locking: called with bdev->bd_mutex held.
  **/
 static int sd_release(struct gendisk *disk, fmode_t mode)
 {
@@ -866,8 +867,7 @@ static int sd_release(struct gendisk *disk, fmode_t mode)
 
        SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_release\n"));
 
-       lock_kernel();
-       if (!--sdkp->openers && sdev->removable) {
+       if (atomic_dec_return(&sdkp->openers) && sdev->removable) {
                if (scsi_block_when_processing_errors(sdev))
                        scsi_set_medium_removal(sdev, SCSI_REMOVAL_ALLOW);
        }
@@ -877,7 +877,6 @@ static int sd_release(struct gendisk *disk, fmode_t mode)
         * XXX is followed by a "rmmod sd_mod"?
         */
        scsi_disk_put(sdkp);
-       unlock_kernel();
        return 0;
 }
 
@@ -930,7 +929,6 @@ static int sd_ioctl(struct block_device *bdev, fmode_t mode,
        SCSI_LOG_IOCTL(1, printk("sd_ioctl: disk=%s, cmd=0x%x\n",
                                                disk->disk_name, cmd));
 
-       lock_kernel();
        /*
         * If we are in the middle of error recovery, don't let anyone
         * else try and use this device.  Also, if error recovery fails, it
@@ -960,7 +958,6 @@ static int sd_ioctl(struct block_device *bdev, fmode_t mode,
                        break;
        }
 out:
-       unlock_kernel();
        return error;
 }
 
@@ -2346,7 +2343,7 @@ static int sd_probe(struct device *dev)
        sdkp->driver = &sd_template;
        sdkp->disk = gd;
        sdkp->index = index;
-       sdkp->openers = 0;
+       atomic_set(&sdkp->openers, 0);
        sdkp->previous_state = 1;
 
        if (!sdp->request_queue->rq_timeout) {