Messages in this thread | | | Date | Fri, 5 Jul 2002 10:47:09 -0700 (PDT) | From | Patrick Mochel <> | Subject | Re: [PATCH] remove BKL from driverfs |
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> > I see no reason to hold the BKL in your situation. I replaced it with > > i_sem in some places and just plain removed it in others. I believe > > that you get all of the protection that you need from dcache_lock in > > the dentry insert and activate. Can you prove me wrong? > > No, and I'm not about to try very hard. It appears that the place you > removed it should be fine. In driverfs_unlink, you replace it with i_sem. > ramfs, which driverfs mimmicks, doesn't hold any lock during unlink. It > seems it could be removed altogether.
Actually, taking i_sem is completely wrong. Look at vfs_unlink() in fs/namei.c:
down(&dentry->d_inode->i_sem); if (d_mountpoint(dentry)) error = -EBUSY; else { error = dir->i_op->unlink(dir, dentry); if (!error) d_delete(dentry); } up(&dentry->d_inode->i_sem);
Then, in driverfs_unlink:
struct inode *inode = dentry->d_inode;
down(&inode->i_sem);
You didn't test this on file removal did you? A good way to verify that you have most of your bases covered is to plug/unplug a USB device a few times. I learned that one from Greg, and it's caught several bugs.
Anyway, I say that the lock can be removed altogether. Ditto for mknod as well.
-pat
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