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Re: [PATCH 5/6] IMA: use rbtree instead of radix tree for inode information cache

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From: Peter Zijlstra
Subject: Re: [PATCH 5/6] IMA: use rbtree instead of radix tree for inode information cache
Date: Wednesday, October 20, 2010 - 4:31 am

On Wed, 2010-10-20 at 10:17 +1100, Dave Chinner wrote:

Correct, what can be made to work is combine RCU with a seqlock. Retry
the lookup using read_seqretry(), RCU here helps to ensure you're not
stepping on already freed memory.


So, tree modification does:

  write_seqlock();
  /* frob RB-tree, using call_rcu() for frees where needed */
  write_sequnlock();

Lookup does:

  unsigned seq;

  rcu_read_lock()
again;
  seq = read_seqbegin();

  /* RB-tree lookup */

  if (read_seqretry(seq))
    goto again;

  rcu_read_unlock();

  return obj;
  


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Messages in current thread:
[PATCH 1/6] IMA: move read/write counters into struct inode, Eric Paris, (Tue Oct 19, 3:58 pm)
[PATCH 2/6] IMA: drop the inode opencount since it isn't n ..., Eric Paris, (Tue Oct 19, 3:58 pm)
[PATCH 3/6] IMA: use unsigned int instead of long for counters, Eric Paris, (Tue Oct 19, 3:58 pm)
[PATCH 4/6] IMA: only allocate iint when needed, Eric Paris, (Tue Oct 19, 3:58 pm)
[PATCH 5/6] IMA: use rbtree instead of radix tree for inod ..., Eric Paris, (Tue Oct 19, 3:58 pm)
[PATCH 6/6] IMA: use i_writecount rather than a private co ..., Eric Paris, (Tue Oct 19, 3:58 pm)
Re: [PATCH 5/6] IMA: use rbtree instead of radix tree for ..., Dave Chinner, (Tue Oct 19, 4:17 pm)
Re: [PATCH 1/6] IMA: move read/write counters into struct ..., Linus Torvalds, (Tue Oct 19, 5:25 pm)
Re: [PATCH 4/6] IMA: only allocate iint when needed, Al Viro, (Tue Oct 19, 8:53 pm)
Re: [PATCH 5/6] IMA: use rbtree instead of radix tree for ..., Peter Zijlstra, (Wed Oct 20, 4:31 am)
Re: [PATCH 5/6] IMA: use rbtree instead of radix tree for ..., Dave Chinner, (Wed Oct 20, 3:05 pm)
Re: [PATCH 5/6] IMA: use rbtree instead of radix tree for ..., Linus Torvalds, (Wed Oct 20, 3:22 pm)
Re: [PATCH 5/6] IMA: use rbtree instead of radix tree for ..., Trond Myklebust, (Wed Oct 20, 3:47 pm)
Re: [PATCH 5/6] IMA: use rbtree instead of radix tree for ..., Linus Torvalds, (Wed Oct 20, 5:58 pm)
Re: [PATCH 5/6] IMA: use rbtree instead of radix tree for ..., Dave Chinner, (Wed Oct 20, 7:17 pm)
Re: [PATCH 1/6] IMA: move read/write counters into struct ..., Eric Paris, (Fri Oct 22, 8:01 pm)
Re: [PATCH 1/6] IMA: move read/write counters into struct ..., Mimi Zohar, (Sat Oct 23, 11:52 pm)