[alsa-devel] [PATCH v2 1/2] remgap: Fix possible sleep-in-atomic in regmap_bulk_write()

[Takashi Iwai]

At Tue, 18 Mar 2014 12:22:18 +0000,
Mark Brown wrote:
> 
> On Tue, Mar 18, 2014 at 12:58:33PM +0100, Takashi Iwai wrote:
> 
> >  		wval = kmemdup(val, val_count * val_bytes, GFP_KERNEL);
> >  		if (!wval) {
> > -			ret = -ENOMEM;
> >  			dev_err(map->dev, "Error in memory allocation\n");
> > -			goto out;
> > +			return -ENOMEM;
> >  		}
> > +		map->lock(map->lock_arg);
> >  		for (i = 0; i < val_count * val_bytes; i += val_bytes)
> >  			map->format.parse_inplace(wval + i);
> >  
> >  		ret = _regmap_raw_write(map, reg, wval, val_bytes * val_count);
> > +		map->unlock(map->lock_arg);
> 
> If we're reducing the locking region here then we should take the lock
> after doing the parse_inplace() to reduce the locked region.  Nothing
> else can be referring to the data since we only just allocated it.  I'll
> fix that by hand and apply.

I thought of that, too, but didn't take it because covering the lock
there doesn't change the fact that it's still fundamentally racy.

> Please also send things to the list for the subsystem (linux-kernel if
> there's not a specific one).

OK, I just copied the previous recipient of the thread...


Takashi