lkml.org 
[lkml]   [2007]   [Jun]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC PATCH 0/6] Convert all tasklets to workqueues
From
Date
 > > [ and on a similar notion, i still havent given up on seeing all BKL 
> > use gone from the kernel. I expect it to happen any decade now ;-) ]

> 2.6.21 had 476 lock_kernel() calls. 2.6.22-git has 473 lock_kernel()
> calls currently. With that kind of flux we'll see the BKL gone in about
> 40 years =B-)

> 'struct semaphore' use on the other hand has gone down by 10% in this
> release, which is a good rate. I guess the lack of lockdep coverage for
> semaphores might be one of the driving forces? ;-)

The problem with removing uses of the BKL is that a "lock_kernel()"
gives no clue about what it is protecting against, and so it requires
a lot of very difficult auditing to replace with appropriate locking.

To take a couple of examples at random: fs/ext4/ioctl.c takes the BKL
in ext4_compat_ioctl() around the call to ext4_ioctl(). Kind of sad
that a "next-generation" FS still uses the BKL, but who understands
things well enough to say how all the cases in ext4_ioctl() are
relying on being called with the BKL held?

As a second example, msr_seek() in arch/i386/kernel/msr.c... is the
inode semaphore enough or not? Who understands the implications well
enough to say?

Most semaphores on the other hand can be replaced by mutexes or
completions in a fairly straightforward way.

- R.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-06-23 00:45    [W:0.170 / U:1.152 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site