Re: FWD: JFFS2 : Node info mutex fix suggestion.

[Gary Thomas <gary at mlbassoc dot com>]

On Mon, 2004-02-16 at 10:07, Andrew Lunn wrote:
> Hi Folks
> 
> Does anybody know how locking should work in the jffs2 package? 
> 
> To me this patch looks the wrong solution. 

I agree.  I did already pass this to David, with no reply :-(

> 
>    Thanks
>         Andrew
> 
> ----- Forwarded message from Alf Nilsson <alf.nilsson@abem.se> -----
> 
> Date: Thu, 12 Feb 2004 17:19:31 +0100
> From: Alf Nilsson <alf.nilsson@abem.se>
> To: ecos-patches@sources.redhat.com
> Subject: JFFS2 : Node info mutex fix suggestion.
> X-Spam-Status: No, hits=-4.9 required=5.0 tests=BAYES_00 autolearn=ham 
> 	version=2.63
> 
> When running a project with priority inheritance we noticed that all the 
> threads that passed though JFFS did not return to their original 
> priority. This due to the mutex count in the jffs2_inode_info was in 
> some cases 2 as lowest. We found that this depended on a call to 
> fs-ecos.c:jffs2_init_inode_info in fs-ecos.c:jffs2_new_inode. The 2nd 
> call in fs-ecos.c:jffs2_new_inode that increases the mutex occurs in 
> read.c:jffs2_do_new_inode.
> This might not be the ultimate solution, but it seemed like the right 
> place to place the patch, but I'm open for suggestions.
> 
> Regards,
> Alf Nilsson
> 
> Index: current/ChangeLog
> ===================================================================
> RCS file: /cvs/ecos/ecos/packages/fs/jffs2/current/ChangeLog,v
> retrieving revision 1.24
> diff -u -w -p -r1.24 ChangeLog
> --- current/ChangeLog	27 Jan 2004 10:49:06 -0000	1.24
> +++ current/ChangeLog	12 Feb 2004 16:01:10 -0000
> @@ -1,3 +1,10 @@
> +2004-02-12  Alf Nilsson  <alf.nilsson@abem.se>
> +
> +	* src/fs-ecos.c: Removed call to jffs2_init_inode_info in
> +	jffs2_new_inode. The call resulted in the mutex in the inode_info
> +	being locked twice. The 2nd lock is in the call to 
> +	jffs2_do_new_inode.
> +
>  2004-01-09  Thomas Koeller  <thomas.koeller@baslerweb.com>
>  
>  	* src/fs-ecos.c: Fixed inode reference counting in jffs2_ops_link().
> Index: current/src/fs-ecos.c
> ===================================================================
> RCS file: /cvs/ecos/ecos/packages/fs/jffs2/current/src/fs-ecos.c,v
> retrieving revision 1.17
> diff -u -w -p -r1.17 fs-ecos.c
> --- current/src/fs-ecos.c	27 Jan 2004 10:49:06 -0000	1.17
> +++ current/src/fs-ecos.c	12 Feb 2004 16:01:11 -0000
> @@ -1849,7 +1849,7 @@ struct _inode *jffs2_new_inode (struct _
>  		return ERR_PTR(-ENOMEM);
>  
>  	f = JFFS2_INODE_INFO(inode);
> -	jffs2_init_inode_info(f);
> +	memset(f, 0, sizeof(*f));
>  
>  	memset(ri, 0, sizeof(*ri));
>  	/* Set OS-specific defaults for new inodes */
> 
> 
> ----- End forwarded message -----
-- 
Gary Thomas <gary@mlbassoc.com>
MLB Associates