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From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: aneesh.kumar@linux.vnet.ibm.com, cmm@us.ibm.com, tytso@mit.edu,
	sandeen@redhat.com, linux-ext4@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH -V3 01/11] percpu_counters: make fbc->count read atomic on 32 bit architecture
Date: Thu, 28 Aug 2008 09:57:37 +0200	[thread overview]
Message-ID: <1219910257.6443.6.camel@twins> (raw)
In-Reply-To: <20080827142250.7397a1a7.akpm@linux-foundation.org>

On Wed, 2008-08-27 at 14:22 -0700, Andrew Morton wrote:

> btw, what the heck is percpu_counter_init_irq()?  Some mysterious
> lockdep-specific thing?
> 
> <does git-fiddle.  Oh.  crappy changelog.>
> 
> I let that one leak through uncommented.  Must be getting old. 
> Probably it will need an EXPORT_SYMBOL() sometime.

Basically all it does it break the percpu_counter lock into two classes.

One for the irq-unsafe users and one for the irq-safe users. Without
this lockdep goes splat complaining about irq recursion deadlocks and
the like between these two separate users.


  parent reply	other threads:[~2008-08-28  7:59 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-08-27 15:28 [PATCH -V3 01/11] percpu_counters: make fbc->count read atomic on 32 bit architecture Aneesh Kumar K.V
2008-08-27 15:28 ` [PATCH -V3 02/11] ext4: Make sure all the block allocation paths reserve blocks Aneesh Kumar K.V
2008-08-27 15:28   ` [PATCH -V3 03/11] ext4: Retry block reservation Aneesh Kumar K.V
2008-08-27 15:28     ` [PATCH -V3 04/11] ext4: Add percpu dirty block accounting Aneesh Kumar K.V
2008-08-27 15:28       ` [PATCH -V3 05/11] ext4: Switch to non delalloc mode when we are low on free blocks count Aneesh Kumar K.V
2008-08-27 15:28         ` [PATCH -V3 06/11] ext4: Update meta-data reservation with delalloc Aneesh Kumar K.V
2008-08-27 15:28           ` [PATCH -V3 07/11] ext4: request for blocks with ar.excepted_group = -1 Aneesh Kumar K.V
2008-08-27 15:28             ` [PATCH -V3 08/11] ext4: Signed arithematic fix Aneesh Kumar K.V
2008-08-27 15:28               ` [PATCH -V3 09/11] ext4: Fix ext4 nomballoc allocator for ENOSPC Aneesh Kumar K.V
2008-08-27 15:28                 ` [PATCH -V3 10/11] ext4: Add inode to journal handle after block allocation for ordered mode Aneesh Kumar K.V
2008-08-27 15:28                   ` [PATCH -V3 11/11] ext4: Retry block allocation if we have free blocks left Aneesh Kumar K.V
2008-08-28 21:57                 ` [PATCH -V3 09/11] ext4: Fix ext4 nomballoc allocator for ENOSPC Mingming Cao
2008-08-29  3:44                   ` Aneesh Kumar K.V
2008-08-29  4:14                     ` Aneesh Kumar K.V
2008-08-29  5:02                       ` Mingming Cao
2008-08-29  5:06                     ` Mingming Cao
2008-08-29  8:25                       ` Aneesh Kumar K.V
2008-08-28 21:04               ` [PATCH -V3 08/11] ext4: Signed arithematic fix Mingming Cao
2008-08-28 21:03             ` [PATCH -V3 07/11] ext4: request for blocks with ar.excepted_group = -1 Mingming Cao
2008-08-28 21:03           ` [PATCH -V3 06/11] ext4: Update meta-data reservation with delalloc Mingming Cao
2008-08-28 20:57         ` [PATCH -V3 05/11] ext4: Switch to non delalloc mode when we are low on free blocks count Mingming Cao
2008-08-28 20:56       ` [PATCH -V3 04/11] ext4: Add percpu dirty block accounting Mingming Cao
2008-10-09 20:44       ` Eric Sandeen
2008-10-10  4:52         ` Aneesh Kumar K.V
2008-10-10  4:58           ` Eric Sandeen
2008-10-11 21:10         ` Andreas Dilger
2008-08-28 20:42     ` [PATCH -V3 03/11] ext4: Retry block reservation Mingming Cao
2008-08-28 20:41   ` [PATCH -V3 02/11] ext4: Make sure all the block allocation paths reserve blocks Mingming Cao
2008-08-27 19:05 ` [PATCH -V3 01/11] percpu_counters: make fbc->count read atomic on 32 bit architecture Andrew Morton
2008-08-27 21:01   ` Peter Zijlstra
2008-08-27 21:22     ` Andrew Morton
2008-08-28  3:52       ` Aneesh Kumar K.V
2008-08-28  4:09         ` Andrew Morton
2008-08-28 22:59           ` Mingming Cao
2008-08-28  7:57       ` Peter Zijlstra [this message]
2008-08-28  3:48   ` Aneesh Kumar K.V
2008-08-28  4:06     ` Andrew Morton
2008-08-28 14:19       ` Nick Piggin

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