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From: Jens Osterkamp <jens@de.ibm.com>
To: Nathan Lynch <ntl@pobox.com>
Subject: Re: [PATCH] RTAS - adapt procfs interface
Date: Wed, 2 Apr 2008 13:33:22 +0200
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On Tuesday 01 April 2008, Nathan Lynch wrote:
> Jens Osterkamp wrote:
> > 
> > Handling of the proc_dir_entry->count has being changed in 2.6.24-rc5.
> 
> Do you know which commit caused the change?

Yes, we bisected it to the following commit :

commit 5a622f2d0f86b316b07b55a4866ecb5518dd1cf7
Author: Alexey Dobriyan <adobriyan@sw.ru>
Date:   Tue Dec 4 23:45:28 2007 -0800

    proc: fix proc_dir_entry refcounting
    
    Creating PDEs with refcount 0 and "deleted" flag has problems (see below).
    Switch to usual scheme:
    * PDE is created with refcount 1
    * every de_get does +1
    * every de_put() and remove_proc_entry() do -1
    * once refcount reaches 0, PDE is freed.
    
    This elegantly fixes at least two following races (both observed) without
    introducing new locks, without abusing old locks, without spreading
    lock_kernel():

    [...]

Gruß,

Jens

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