Re: [PATCH] Reduce stack used by lib/hexdump.c

[Kyle Moffett <mrmacman_g4@mac.com>]

On Dec 05, 2007, at 21:42:35, Joe Perches wrote:
> On Wed, 2007-12-05 at 18:18 -0800, Randy Dunlap wrote:
> > Joe Perches wrote:
> > > Maybe just eliminate the 16 or 32 byte width option and force it  
> > > to only 16 byte widths.
> > Have you checked users (callers)?  I'm pretty sure that one of the  
> > callers wanted 32 and that's why it's there.
>
> I did.  There is only 1 subsystem.  That's easy to change.
>
> drivers/mtd/ubi/debug.c:  print_hex_dump(KERN_DEBUG, "",  
> DUMP_PREFIX_OFFSET, 32, 1,
> drivers/mtd/ubi/io.c:     print_hex_dump(KERN_DEBUG, "",  
> DUMP_PREFIX_OFFSET, 32, 1,
>
> Long lines in the log file are not too easy to read anyway.  Using  
> 16 byte dumps per line instead of 32 isn't painful.
>
> It gets rid of the allocation, reduces the argument count and makes  
> the kernel smaller.  I think it's all good.
>
> Every current caller would have to change though.

Alternatively, since print_hex_dump is not a performance-critical  
path (and usually indicates an error/debug condition), you could  
probably just make a static "hexdump_lock" spinlock and  
spin_lock_irqsave()/spin_unlock_irqrestore().  It would always nest  
inside any other lock (except during crash, where we break locks  
already for printk()), and I doubt any of the callers would notice  
the serialization since they're already serialized on the printk buffer.

Cheers,
Kyle Moffett

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