From: Linus Torvalds <torvalds@linux-foundation.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Eric Paris <eparis@redhat.com>,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-fsdevel@vger.kernel.org, hch@infradead.org,
zohar@us.ibm.com, warthog9@kernel.org, jmorris@namei.org,
kyle@mcmartin.ca, hpa@zytor.com, akpm@linux-foundation.org,
mingo@elte.hu, viro@zeniv.linux.org.uk
Subject: Re: [PATCH 5/6] IMA: use rbtree instead of radix tree for inode information cache
Date: Wed, 20 Oct 2010 15:22:21 -0700 [thread overview]
Message-ID: <AANLkTikoPoV=OYjzX9+Rd5tWERS+n8sFejJuot7++ONP@mail.gmail.com> (raw)
In-Reply-To: <20101020220557.GN32255@dastard>
On Wed, Oct 20, 2010 at 3:05 PM, Dave Chinner <david@fromorbit.com> wrote:
>
> /me wanders off to look at converting the xfs buffer cache rbtrees
> to RCU....
Look out for livelocks, though. And yes, they can happen.
So rather than a loop, one option is to do basically
rcu_read_lock();
seq = read_seqbegin();
.. do lookup ..
need_lock = read_seqretry(seq);
rcu_read_unlock();
if (need_lock) {
get_real_lock();
.. do lookup ..
drop_real_lock();
}
which just falls back to a locked access if the rcu model doesn't work.
Linus
next prev parent reply other threads:[~2010-10-20 22:27 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-19 22:58 [PATCH 1/6] IMA: move read/write counters into struct inode Eric Paris
2010-10-19 22:58 ` [PATCH 2/6] IMA: drop the inode opencount since it isn't needed for operation Eric Paris
2010-10-19 22:58 ` [PATCH 3/6] IMA: use unsigned int instead of long for counters Eric Paris
2010-10-19 22:58 ` [PATCH 4/6] IMA: only allocate iint when needed Eric Paris
2010-10-20 3:53 ` Al Viro
2010-10-19 22:58 ` [PATCH 5/6] IMA: use rbtree instead of radix tree for inode information cache Eric Paris
2010-10-19 23:17 ` Dave Chinner
2010-10-20 11:31 ` Peter Zijlstra
2010-10-20 22:05 ` Dave Chinner
2010-10-20 22:22 ` Linus Torvalds [this message]
2010-10-20 22:47 ` Trond Myklebust
2010-10-21 0:58 ` Linus Torvalds
2010-10-21 2:17 ` Dave Chinner
2010-10-19 22:58 ` [PATCH 6/6] IMA: use i_writecount rather than a private counter Eric Paris
2010-10-20 0:25 ` [PATCH 1/6] IMA: move read/write counters into struct inode Linus Torvalds
2010-10-23 3:01 ` Eric Paris
2010-10-24 6:52 ` Mimi Zohar
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