Every user of the BKL in the sd driver is the
result of the pushdown from the block layer
into the open/close/ioctl functions.
The only place that used to rely on the BKL is
the sdkp->openers variable, which gets converted
into an atomic_t.
Nothing else seems to rely on the BKL, since the
functions do not touch global data without holding
another lock, and the open/close functions are
still protected from concurrent execution using
the bdev->bd_mutex.
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: linux-scsi@xxxxxxxxxxxxxxx
Cc: "James E.J. Bottomley" <James.Bottomley@xxxxxxx>
---
drivers/scsi/sd.c | 17 +++++++----------
drivers/scsi/sd.h | 2 +-
2 files changed, 8 insertions(+), 11 deletions(-)
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index cf1441f..a0142a7 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -746,6 +746,8 @@ 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)
{
@@ -758,7 +760,6 @@ 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;
/*
@@ -797,17 +798,15 @@ 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;
}
@@ -821,6 +820,8 @@ 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)
{
@@ -829,8 +830,7 @@ 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);
}
@@ -840,7 +840,6 @@ 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;
}
@@ -893,7 +892,6 @@ 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
@@ -923,7 +921,6 @@ static int sd_ioctl(struct block_device *bdev, fmode_t mode,
break;
}
out:
- unlock_kernel();
return error;
}
@@ -2317,7 +2314,7 @@ 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) {
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 43d3caf..f81a930 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -47,7 +47,7 @@ struct scsi_disk {
struct scsi_device *device;
struct device dev;
struct gendisk *disk;
- unsigned int openers; /* protected by BKL for now, yuck */
+ atomic_t openers;
sector_t capacity; /* size in 512-byte sectors */
u32 index;
unsigned short hw_sector_size;
--
1.7.0.4
--
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