linux-kernel - Re: [PATCH] remove the BKL: remove "BKL auto-drop" assumption from nfs3_rpc

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Date:	Fri, 10 Apr 2009 20:29:37 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Alessio Igor Bogani <abogani@...ware.it>
Cc:	Ingo Molnar <mingo@...e.hu>, Jonathan Corbet <corbet@....net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] remove the BKL: remove "BKL auto-drop" assumption from
	nfs3_rpc_wrapper()

On Fri, Apr 10, 2009 at 06:34:41PM +0200, Alessio Igor Bogani wrote:
> Fix nfs3_rpc_wrapper()'s "schedule() drops the BKL automatically" assumption,
> when schedule_timeout_killable() does not do that it can lock up.
> 
> Signed-off-by: Alessio Igor Bogani <abogani@...ware.it>


Hi Alessio,

Btw, does it fix the lockdep message you've seen while mounting
an nfs point?

Thanks,
Frederic.


> ---
>  fs/nfs/nfs3proc.c |    7 +++++++
>  1 files changed, 7 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
> index d0cc5ce..d91047c 100644
> --- a/fs/nfs/nfs3proc.c
> +++ b/fs/nfs/nfs3proc.c
> @@ -17,6 +17,7 @@
>  #include <linux/nfs_page.h>
>  #include <linux/lockd/bind.h>
>  #include <linux/nfs_mount.h>
> +#include <linux/smp_lock.h>
>  
>  #include "iostat.h"
>  #include "internal.h"
> @@ -28,11 +29,17 @@ static int
>  nfs3_rpc_wrapper(struct rpc_clnt *clnt, struct rpc_message *msg, int flags)
>  {
>  	int res;
> +	int bkl = kernel_locked();
> +
>  	do {
>  		res = rpc_call_sync(clnt, msg, flags);
>  		if (res != -EJUKEBOX)
>  			break;
> +		if (bkl)
> +			unlock_kernel();
>  		schedule_timeout_killable(NFS_JUKEBOX_RETRY_TIME);
> +		if (bkl)
> +			lock_kernel();
>  		res = -ERESTARTSYS;
>  	} while (!fatal_signal_pending(current));
>  	return res;
> -- 
> 1.6.0.4
> 

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