On Tue, Aug 27, 2019 at 3:00 PM shuah <shuah@xxxxxxxxxx> wrote: > > On 8/27/19 3:36 PM, Brendan Higgins wrote: > > On Tue, Aug 27, 2019 at 2:09 PM Brendan Higgins > > <brendanhiggins@xxxxxxxxxx> wrote: > >> > >> On Tue, Aug 27, 2019 at 2:03 PM Brendan Higgins > >> <brendanhiggins@xxxxxxxxxx> wrote: > >>> > >>> On Tue, Aug 27, 2019 at 1:21 PM shuah <shuah@xxxxxxxxxx> wrote: > >>>> > >>>> On 8/27/19 11:49 AM, Brendan Higgins wrote: > >>>>> Previously KUnit assumed that printk would always be present, which is > >>>>> not a valid assumption to make. Fix that by ifdefing out functions which > >>>>> directly depend on printk core functions similar to what dev_printk > >>>>> does. > >>>>> > >>>>> Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> > >>>>> Link: https://lore.kernel.org/linux-kselftest/0352fae9-564f-4a97-715a-fabe016259df@xxxxxxxxxx/T/#t > >>>>> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> > >>>>> Signed-off-by: Brendan Higgins <brendanhiggins@xxxxxxxxxx> > >>>>> --- > >>>>> include/kunit/test.h | 7 +++++++ > >>>>> kunit/test.c | 41 ++++++++++++++++++++++++----------------- > >>>>> 2 files changed, 31 insertions(+), 17 deletions(-) > >>>>> > >>>>> diff --git a/include/kunit/test.h b/include/kunit/test.h > >>>>> index 8b7eb03d4971..339af5f95c4a 100644 > >>>>> --- a/include/kunit/test.h > >>>>> +++ b/include/kunit/test.h > >>>>> @@ -339,9 +339,16 @@ static inline void *kunit_kzalloc(struct kunit *test, size_t size, gfp_t gfp) > >>> [...] > >>>> Okay after reviewing this, I am not sure why you need to do all > >>>> this. > >>>> > >>>> Why can't you just change the root function that throws the warn: > >>>> > >>>> static int kunit_vprintk_emit(int level, const char *fmt, va_list args) > >>>> { > >>>> return vprintk_emit(0, level, NULL, 0, fmt, args); > >>>> } > >>>> > >>>> You aren'r really doing anything extra here, other than calling > >>>> vprintk_emit() > >>> > >>> Yeah, I did that a while ago. I think it was a combination of trying > >>> to avoid an extra layer of adding and then removing the log level, and > >>> that's what dev_printk and friends did. > >>> > >>> But I think you are probably right. It's a lot of maintenance overhead > >>> to get rid of that. Probably best to just use what the printk people > >>> have. > >>> > >>>> Unless I am missing something, can't you solve this problem by including > >>>> printk.h and let it handle the !CONFIG_PRINTK case? > >>> > >>> Randy, I hope you don't mind, but I am going to ask you to re-ack my > >>> next revision since it basically addresses the problem in a totally > >>> different way. > >> > >> Actually, scratch that. Checkpatch doesn't like me calling printk > >> without using a KERN_<LEVEL>. > >> > >> Now that I am thinking back to when I wrote this. I think it also > >> might not like using a dynamic KERN_<LEVEL> either (printk("%s my > >> message", KERN_INFO)). > >> > >> I am going to have to do some more investigation. > > > > Alright, I am pretty sure it is safe to do printk("%smessage", KERN_<LEVEL>); > > > > Looking at the printk implementation, it appears to do the format > > before it checks the log level: > > > > https://elixir.bootlin.com/linux/v5.2.10/source/kernel/printk/printk.c#L1907 > > > > So I am pretty sure we can do it either with the vprintk_emit or with printk. > > Let me see if we are on the same page first. I am asking if you can > just include printk.h for vprintk_emit() define for both CONFIG_PRINTK > and !CONFIG_PRINTK cases. Ah sorry, I misunderstood you. No, that doesn't work. I tried including linux/printk.h, and I get the same error. The reason for this is that vprintk_emit() is only defined when CONFIG_PRINTK=y: https://elixir.bootlin.com/linux/latest/ident/vprintk_emit > I am not asking you to use printk() in place of vprintk_emit(). > It is perfectly fine to use vprintk_emit() Okay, cool. > > > > So it appears that we have to weigh the following trade-offs: > > > > Using vprintk_emit: > > > > Pros: > > - That's what dev_printk uses. > > Not sure what you mean by this. I am suggesting if you can just > call vprintk_emit() and include printk.h and not have to ifdef > around all the other callers of kunit_vprintk_emit() Oh, I was just saying that I heavily based my implementation of kunit_printk on dev_printk. So I have a high degree of confidence that it is okay to use it the way that I am using it. > Yes. There is the other issue of why do you need the complexity > of having kunit_vprintk_emit() at all. Right, and the problem with the alternative, is there is no good kernel API for logging with the log level set dynamically. printk prefers to have it as a string prefix on the format string, but I cannot do that because I need to add my own prefix to the format string. So, I guess I should just go ahead and address the earlier comments on this patch?
