On Thu, 2017-10-12 at 14:08 +0200, Greg Kroah-Hartman wrote: > On Thu, Oct 12, 2017 at 01:52:29PM +0200, Greg Kroah-Hartman wrote: > > On Thu, Oct 12, 2017 at 01:34:39PM +0200, Peter Zijlstra wrote: > > > On Thu, Oct 12, 2017 at 12:03:04PM +0200, Petr Mladek wrote: > > > > On Thu 2017-10-12 11:45:37, Petr Mladek wrote: > > > > > Hi, > > > > > > > > > > I thought about this a lot from several angles. And I would prefer > > > > > sligly different placement, see the patch below. > > > > > > > > > > On Thu 2017-09-28 14:18:24, Peter Zijlstra wrote: > > > > > > Some people figured vprintk_emit() makes for a nice API and exported > > > > > > it, bypassing the kdb trap. > > > > > > > > > > Sigh, printk() API is pretty complicated and this export > > > > > made it much worse. Well, there are two things: > > > > > > > > > > First, kdb_trap_printk name is a bit misleading. It is not a > > > > > generic trap of any printk message. Instead it seems to be > > > > > used to redirect only particular messages from some existing > > > > > functions, e.g. show_regs() called from kdb_dumpregs(). > > > > > > > > > > Second, it seems that the only user of the exported vprintk_emit() > > > > > is dev_vprintk_emit(). I believe that code using this wrapper > > > > > is not called in the sections where kdb_trap_printk is incremented. > > > > > > > > Well, I wonder if we should go even further and stop exporting > > > > vprintk_emit(). IMHO, the only reason was dev_print_emit() and > > > > the ability to pass the extra "dict" parameter. > > > > > > You have my blessing there, but the device folks might have an opinion > > > on that; Cc'ed Gregkh. > > > > Hm, we "need" that dict option, otherwise the whole dev_printk() family > > of messages will not work properly, right? > > > > Or am I missing something? If you can figure out a way to still support > > the same thing (we need a prefix at the beginning of the message that > > shows the device/driver/binding/etc that emitted the message), that's > > fine with me, I'm not wed to vprintk_emit() :) > > Nope, this doesn't seem to deal with the prefix, except in some odd way > that is tied to the dynamic debugging logic. I really don't know what > this does anymore. Joe wrote it in 2012 as part of the dynamic debug > code. > > Joe, any thoughts?
Man I hate rabbit-holes. I need a few days as I'm otherwise busy. This stuff has been broken for half a decade now. Perhaps it doesn't need fixing? In any case, printk needs a thorough breaking up and refactoring. Pushing around at its edges just makes it worse. vprintk_emit came from Kay Sievers. commit 7ff9554bb578ba02166071d2d487b7fc7d860d62 Author: Kay Sievers <[email protected]> Date: Thu May 3 02:29:13 2012 +0200 printk: convert byte-buffer to variable-length record buffer It seems printk_emit is also exported and unused.
