Matt Mackall wrote: > I suppose. I still find this approach less than ideal, especially > putting something potentially large on the stack. The dangers are > perhaps worse than a malloc, really. I pondered on this a bit but the thing is we already use several hundreds bytes in a function which builds complex messages. The original ata_eh_report() implementation allocates 424 bytes on stack for temp buffers and local variables. In addition to that, it calls printk with upto 30 arguments (~240 bytes). While the new implementation allocates 232 bytes sans the buffer and the maximum number of arguments is about sixteen (~128 bytes). ata_eh_report() uses a fixed buffer but 320byte buffer should be sufficient. In total, it's 664 vs 680 and that's for a really big message. mprintk also allows fixed or malloc'd buffers so if you wanna go bigger, malloc'd buffer should do the job. > I also don't like your interface much. Consider this alternative: > > struct mprintk *mp = mprintk_begin(KERN_INFO "ata%u.%2u: ", 1, 0); > mprintk(mp, "ATA %d", 7); > mprintk(mp, ", %u sectors\n", 1024); > mprintk(mp, "everything seems dandy\n"); > mprintk_end(mp); > > That keeps all the "normal" printks short and makes the flush more > explict. I like that the more used function is shorter. Hmmm... The reason why I first used mprintk_push() is to make it clear that the function accumulates messages unlike mprintk() which flushes what's accumulated and prints its own message. > Now we make mprintk_begin attempt to do a kmalloc of a moderate size > (512 bytes?) and failing that, return null. Then mprintk can fall > through to printk in the NULL case. If you wanna do that implicitly, you need GFP_ flag in mprintk_begin() and atomic allocation should be used from interrupt handlers and friends and they fail easily under the right (or wrong) conditions. Forcing kmalloc isn't a good idea. Having multiple initializers is one way to do it. Any suggestions? Thanks. -- tejun - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
