Re: [PATCH: 2.6.20-rc4-mm1] JFS: Avoid deadlock introduced byexplicit I/O plugging

[Dave Kleikamp]

On Thu, 2007-01-18 at 01:30 -0500, Josef Sipek wrote:
> On Wed, Jan 17, 2007 at 04:55:49PM -0600, Dave Kleikamp wrote:

> >  /*
> >   *	jfs_lock.h
> > @@ -42,6 +43,7 @@ do {							\
> >  		if (cond)				\
> >  			break;				\
> >  		unlock_cmd;				\
> > +		blk_replug_current_nested();		\
> >  		schedule();				\
> >  		lock_cmd;				\
> >  	}						\
> 
> Is {,un}lock_cmd a macro? ...

They are the commands passed into this macro (as arguments) to
release/take a lock.  This is a home-grown wait_on_event type macro
where the condition must be checked while holding a lock.  And the
commands passed in are themselves macros.  The jfs code could probably
be cleaned up a bit as far as excessive use of macros for locking, but
it's been working for a few years with few problems.

-- 
David Kleikamp
IBM Linux Technology Center

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