* RE: + big-kernel-lock-contention-in-do_open-and-blkdev_put.patchadded to -mm tree
2006-06-01 8:14 ` + big-kernel-lock-contention-in-do_open-and-blkdev_put.patch added to -mm tree Arjan van de Ven
@ 2006-06-01 18:19 ` Chen, Kenneth W
0 siblings, 0 replies; 2+ messages in thread
From: Chen, Kenneth W @ 2006-06-01 18:19 UTC (permalink / raw)
To: 'Arjan van de Ven', linux-kernel; +Cc: akpm
Arjan van de Ven wrote on Thursday, June 01, 2006 1:15 AM
> > Out of the 63 hits I see in 2.6.17-rc4 with
> > block_device_operations->open(), floppy driver seems to be the only one
> > that mucks around with a global Variable without any protection. We can
> > add a spin lock there.
> > ---
> >
> > fs/block_dev.c | 6 ------
> > 1 file changed, 6 deletions(-)
>
> the fix to floppy.c is missing!
See below for the follow on patch that adds a lock in amiga floppy
open/release method.
> (also I highly question the validity of this patch, last time the BKL
> got dropped from open quite a few rootholes got opened... )
I will be watching bug report on this. If I miss any, I would appreciate
people forward bug report to me and I will fix it!
[patch] add BKL in amiga floppy open/release method since the generic
block device open/release method no longer holds the BKL.
Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
--- ./drivers/block/amiflop.c.orig 2006-06-01 11:43:42.000000000 -0700
+++ ./drivers/block/amiflop.c 2006-06-01 12:10:23.000000000 -0700
@@ -64,6 +64,7 @@
#include <linux/buffer_head.h>
#include <linux/blkdev.h>
#include <linux/elevator.h>
+#include <linux/smp_lock.h>
#include <asm/setup.h>
#include <asm/uaccess.h>
@@ -1591,10 +1592,21 @@ static int floppy_open(struct inode *ino
return 0;
}
+static int floppy_open_lock(struct inode *inode, struct file *filp)
+{
+ int ret;
+
+ lock_kernel();
+ ret = floppy_open(inode, filp);
+ unlock_kernel();
+ return ret;
+}
+
static int floppy_release(struct inode * inode, struct file * filp)
{
int drive = iminor(inode) & 3;
+ lock_kernel();
if (unit[drive].dirty == 1) {
del_timer (flush_track_timer + drive);
non_int_flush_track (drive);
@@ -1608,6 +1620,7 @@ static int floppy_release(struct inode *
/* the mod_use counter is handled this way */
floppy_off (drive | 0x40000000);
#endif
+ unlock_kernel();
return 0;
}
@@ -1647,7 +1660,7 @@ static int amiga_floppy_change(struct ge
static struct block_device_operations floppy_fops = {
.owner = THIS_MODULE,
- .open = floppy_open,
+ .open = floppy_open_lock,
.release = floppy_release,
.ioctl = fd_ioctl,
.getgeo = fd_getgeo,
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