Remaining BKL users, what to do
Arnd Bergmann
arnd at arndb.de
Thu Sep 16 07:32:59 PDT 2010
The big kernel lock is gone from almost all code in linux-next, this is
the status of what I think will happen to the remaining users:
drivers/gpu/drm/i810/{i810,i830}_dma.c:
Fixable, but needs someone with the hardware to test. Can probably be
marked CONFIG_BROKEN_ON_SMP if nobody cares.
drivers/media/video (V4L):
Mauro is working on it, some drivers get moved to staging while the
others get fixed. An easy workaround would be possible by adding
per-driver mutexes, but Mauro wants to it properly by locking all
the right places.
fs/adfs:
Probably not hard to fix, but needs someone to test it.
adfs has only seen janitorial fixes for the last 5 years.
Do we know of any users?
fs/autofs:
Pretty much dead, replaced by autofs4. I'd suggest moving this
to drivers/staging in 2.6.37 and letting it die there.
fs/coda:
Coda seems to have an active community, but not all of their
code is actually part of linux (pioctl!), while the last official
release is missing many of the cleanups that were don in Linux.
Not sure what to do, if someone is interested, the best way might
be a fresh start with a merger of the mainline linux and the
coda.cs.cmu.edu codebase in drivers/staging.
Just removing the BKL without the Coda community seems like a heap
of pointless work.
fs/freevxfs:
Uses the BKL in readdir and lookup, should be easy to fix. Christoph?
fs/hpfs:
Looks fixable, if anyone cares. Maybe it's time for retirement in
drivers/staging though. The web page only has a Link to the
linux-2.2 version.
fs/lockd:
Trond writes that he has someone working on BKL removal here.
fs/locks.c:
Patch is under discussion, blocked by work on fs/lockd currently.
fs/ncpfs:
Should be fixable if Petr still cares about it. Otherwise suggest
moving to drivers/staging if there are no users left.
fs/qnx4:
Should be easy to fix, there are only a few places in the code that
use the BKL. Anders?
fs/smbfs:
Last I heard this was considered obsolete. Should be move it to
drivers/staging now?
fs/udf:
Not completely trivial, but probably necessary to fix. Project web
site is dead, I hope that Jan Kara can be motivated to fix it though.
fs/ufs:
Evgeniy Dushistov is maintaining this, I hope he can take care of
getting rid of the BKL in UFS.
kernel/trace/blktrace.c:
Should be easy. Ingo? Steven?
net/appletalk:
net/ipx/af_ipx.c:
net/irda/af_irda.c:
Can probably be saved from retirement in drivers/staging if the
maintainers still care.
net/x25:
Andrew Hendry has started working on it.
This is all that's left now. I still need to submit a few patches for
simple file system changes, but it seems we're getting closer to finally
killing it for good.
Arnd
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