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Message-ID: <20100704080146.GA31828@merkur.ravnborg.org>
Date: Sun, 4 Jul 2010 10:01:46 +0200
From: Sam Ravnborg <sam@...nborg.org>
To: Arnd Bergmann <arnd@...db.de>
Cc: Jens Axboe <axboe@...nel.dk>,
Christoph Hellwig <hch@...radead.org>,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
John Kacur <jkacur@...hat.com>,
Frederic Weisbecker <fweisbec@...il.com>,
linux-scsi@...r.kernel.org
Subject: Re: [PATCH 2/6] block: push down BKL into .open and .release
>
> static int DAC960_getgeo(struct block_device *bdev, struct hd_geometry *geo)
> diff --git a/drivers/block/amiflop.c b/drivers/block/amiflop.c
> index 7a51535..8af7af7 100644
> --- a/drivers/block/amiflop.c
> +++ b/drivers/block/amiflop.c
> @@ -1555,10 +1555,13 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
> int old_dev;
> unsigned long flags;
>
> + lock_kernel();
> old_dev = fd_device[drive];
>
> - if (fd_ref[drive] && old_dev != system)
> + if (fd_ref[drive] && old_dev != system) {
> + unlock_kernel();
> return -EBUSY;
> + }
>
> if (mode & (FMODE_READ|FMODE_WRITE)) {
> check_disk_change(bdev);
> @@ -1571,8 +1574,10 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
> fd_deselect (drive);
> rel_fdc();
>
> - if (wrprot)
> + if (wrprot) {
> + unlock_kernel();
> return -EROFS;
> + }
> }
> }
>
> @@ -1589,6 +1594,7 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
> printk(KERN_INFO "fd%d: accessing %s-disk with %s-layout\n",drive,
> unit[drive].type->name, data_types[system].name);
>
> + unlock_kernel();
> return 0;
> }
Using goto for errorhandling here would have been nicer.
Also did you forget to include smp_locks.h?
>
> @@ -1597,6 +1603,7 @@ static int floppy_release(struct gendisk *disk, fmode_t mode)
> struct amiga_floppy_struct *p = disk->private_data;
> int drive = p - unit;
>
> + lock_kernel();
> if (unit[drive].dirty == 1) {
> del_timer (flush_track_timer + drive);
> non_int_flush_track (drive);
> @@ -1610,6 +1617,7 @@ static int floppy_release(struct gendisk *disk, fmode_t mode)
> /* the mod_use counter is handled this way */
> floppy_off (drive | 0x40000000);
> #endif
> + unlock_kernel();
> return 0;
> }
Cooked up the following replacement patch:
[Not build tested]
diff --git a/drivers/block/amiflop.c b/drivers/block/amiflop.c
index 832798a..25d63cf 100644
--- a/drivers/block/amiflop.c
+++ b/drivers/block/amiflop.c
@@ -67,6 +67,7 @@
#include <linux/elevator.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
+#include <linux/smp_lock.h>
#include <asm/setup.h>
#include <asm/uaccess.h>
@@ -1541,11 +1542,16 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
int system = (MINOR(bdev->bd_dev) & 4) >> 2;
int old_dev;
unsigned long flags;
+ int err;
+ err = 0;
+ lock_kernel();
old_dev = fd_device[drive];
- if (fd_ref[drive] && old_dev != system)
- return -EBUSY;
+ if (fd_ref[drive] && old_dev != system) {
+ err = -EBUSY;
+ goto out;
+ }
if (mode & (FMODE_READ|FMODE_WRITE)) {
check_disk_change(bdev);
@@ -1558,8 +1564,10 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
fd_deselect (drive);
rel_fdc();
- if (wrprot)
- return -EROFS;
+ if (wrprot) {
+ err = -EROFS;
+ goto out;
+ }
}
}
@@ -1576,7 +1584,9 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
printk(KERN_INFO "fd%d: accessing %s-disk with %s-layout\n",drive,
unit[drive].type->name, data_types[system].name);
- return 0;
+out:
+ unlock_kernel();
+ return err;
}
static int floppy_release(struct gendisk *disk, fmode_t mode)
@@ -1584,6 +1594,7 @@ static int floppy_release(struct gendisk *disk, fmode_t mode)
struct amiga_floppy_struct *p = disk->private_data;
int drive = p - unit;
+ lock_kernel();
if (unit[drive].dirty == 1) {
del_timer (flush_track_timer + drive);
non_int_flush_track (drive);
@@ -1597,6 +1608,7 @@ static int floppy_release(struct gendisk *disk, fmode_t mode)
/* the mod_use counter is handled this way */
floppy_off (drive | 0x40000000);
#endif
+ unlock_kernel();
return 0;
}
Feel free to use this as is.
> +++ b/drivers/block/aoe/aoeblk.c
> @@ -12,6 +12,7 @@
> #include <linux/slab.h>
> #include <linux/genhd.h>
> #include <linux/netdevice.h>
> +#include <linux/smp_lock.h>
> #include "aoe.h"
>
> static struct kmem_cache *buf_pool_cache;
> @@ -124,13 +125,16 @@ aoeblk_open(struct block_device *bdev, fmode_t mode)
> struct aoedev *d = bdev->bd_disk->private_data;
> ulong flags;
>
> + lock_kernel();
> spin_lock_irqsave(&d->lock, flags);
> if (d->flags & DEVFL_UP) {
> d->nopen++;
> spin_unlock_irqrestore(&d->lock, flags);
> + unlock_kernel();
> return 0;
> }
> spin_unlock_irqrestore(&d->lock, flags);
> + unlock_kernel();
> return -ENODEV;
> }
"goto out" would be cleaner.
> diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
> index 1f70aec..4f2e12f 100644
> --- a/drivers/block/pktcdvd.c
> +++ b/drivers/block/pktcdvd.c
> @@ -2383,6 +2383,7 @@ static int pkt_open(struct block_device *bdev, fmode_t mode)
>
> VPRINTK(DRIVER_NAME": entering open\n");
>
> + lock_kernel();
> mutex_lock(&ctl_mutex);
> pd = pkt_find_dev_from_minor(MINOR(bdev->bd_dev));
> if (!pd) {
> @@ -2410,6 +2411,7 @@ static int pkt_open(struct block_device *bdev, fmode_t mode)
> }
>
> mutex_unlock(&ctl_mutex);
> + unlock_kernel();
> return 0;
>
> out_dec:
> @@ -2417,6 +2419,7 @@ out_dec:
> out:
> VPRINTK(DRIVER_NAME": failed open (%d)\n", ret);
> mutex_unlock(&ctl_mutex);
> + unlock_kernel();
> return ret;
> }
>
> @@ -2425,6 +2428,7 @@ static int pkt_close(struct gendisk *disk, fmode_t mode)
> struct pktcdvd_device *pd = disk->private_data;
> int ret = 0;
>
> + lock_kernel();
> mutex_lock(&ctl_mutex);
> pd->refcnt--;
> BUG_ON(pd->refcnt < 0);
> @@ -2433,6 +2437,7 @@ static int pkt_close(struct gendisk *disk, fmode_t mode)
> pkt_release_dev(pd, flush);
> }
> mutex_unlock(&ctl_mutex);
> + unlock_kernel();
> return ret;
> }
Improved "goto" errorhandling would be nicer.
Is smp_lock.h included by other files?
Replacement patch (not build tested...):
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 8a549db..30d585d 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -59,6 +59,8 @@
#include <linux/freezer.h>
#include <linux/mutex.h>
#include <linux/slab.h>
+#include <linux/smp_lock.h>
+
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/scsi.h>
@@ -2382,11 +2384,12 @@ static int pkt_open(struct block_device *bdev, fmode_t mode)
VPRINTK(DRIVER_NAME": entering open\n");
+ lock_kernel();
mutex_lock(&ctl_mutex);
pd = pkt_find_dev_from_minor(MINOR(bdev->bd_dev));
if (!pd) {
ret = -ENODEV;
- goto out;
+ goto out_fail;
}
BUG_ON(pd->refcnt < 0);
@@ -2408,14 +2411,16 @@ static int pkt_open(struct block_device *bdev, fmode_t mode)
set_blocksize(bdev, CD_FRAMESIZE);
}
- mutex_unlock(&ctl_mutex);
- return 0;
+ ret = 0;
+ goto out;
out_dec:
pd->refcnt--;
-out:
+out_fail:
VPRINTK(DRIVER_NAME": failed open (%d)\n", ret);
+out:
mutex_unlock(&ctl_mutex);
+ unlock_kernel();
return ret;
}
Lot's of other places could benefit from improved goto error handling.
The driver maintainers should do this (if there is a maintainer).
I stopped with the small replacement patches.
I did not find anything else going through this patch.
Sam
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