On 09/01/2014 12:19 AM, Christoph Hellwig wrote: > On Thu, Aug 28, 2014 at 07:33:27PM +0200, Hannes Reinecke wrote: >> SCSI opcode printing is tricky and needs to take into account >> several different corner cases. So instead of trying to come >> up with an elaborate printk() statement we should be printing >> it into a local buffer. > > scsi_print_command callers are usually deep down the call chain., so I'd > rather avoid using up even more stack here. What are the exact reasons > that we need the local buffer? > I know, and I'm not happy with this patch, either. However, we really, _really_, want to print the decode command name and the CDB in one line ie with one printk() statement. If we don't we'll end up with individual logging messages with one byte per line under high load. Making it impossible to figure out to which CDB these individual bytes are related to. It would be possible to unroll the CDB decoding loop, as we're typically have only 3 formats. But it's near impossible to find some common ground when decoding the command; I've ended up having really convoluted #defines calling into each other, making debugging that code really horrible. You're more than welcome to try... But for now I fear we have to bite the bullet, and ensure the additional stack space it only used when logging is enabled. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
