linux-kernel - Re: [PATCH 1/6] kill-the-BKL/reiserfs: release write lock on fs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 01 May 2009 08:31:12 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>,
	Jeff Mahoney <jeffm@...e.com>,
	ReiserFS Development List <reiserfs-devel@...r.kernel.org>,
	Chris Mason <chris.mason@...cle.com>,
	Alexander Beregalov <a.beregalov@...il.com>,
	Alessio Igor Bogani <abogani@...ware.it>,
	Jonathan Corbet <corbet@....net>,
	Alexander Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH 1/6] kill-the-BKL/reiserfs: release write lock on fs_changed()

Frederic Weisbecker <fweisbec@...il.com> writes:
>
> diff --git a/include/linux/reiserfs_fs.h b/include/linux/reiserfs_fs.h
> index 6587b4e..397d281 100644
> --- a/include/linux/reiserfs_fs.h
> +++ b/include/linux/reiserfs_fs.h
> @@ -1302,7 +1302,13 @@ static inline loff_t max_reiserfs_offset(struct inode *inode)
>  #define get_generation(s) atomic_read (&fs_generation(s))
>  #define FILESYSTEM_CHANGED_TB(tb)  (get_generation((tb)->tb_sb) != (tb)->fs_gen)
>  #define __fs_changed(gen,s) (gen != get_generation (s))
> -#define fs_changed(gen,s) ({cond_resched(); __fs_changed(gen, s);})
> +#define fs_changed(gen,s)		\
> +({					\
> +	reiserfs_write_unlock(s);	\
> +	cond_resched();			\
> +	reiserfs_write_lock(s);		\

Did you try writing that 

    if (need_resched()) {               \
	reiserfs_write_unlock(s);	\
	cond_resched();			\  (or schedule(), but cond_resched does a loop)
	reiserfs_write_lock(s);		\
    }				

? That might give better performance under load because users will be better
batched and you don't release the lock unnecessarily in the unloaded case.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/