On Tue, Aug 27, 2019 at 3:55 PM shuah <shuah@xxxxxxxxxx> wrote: > > On 8/27/19 4:16 PM, Brendan Higgins wrote: > > 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: > > > > This is the real problem here. printk.h defines several for > !CONFIG_PRINTK case. Yeah, Tim pointed that out. I think both of you are right, I should be filing my fix against them. > > 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? > > > > So what does your code do in the case of !CONFIG_PRINTK. From my read of > it, it returns 0 from kunit_printk_emit(0 from my read of it. What I am > saying is this is a lot of indirection instead of fixing the leaf > function which is kunit_vprintk_emit(). Agreed. My apologies, as I mentioned in response to Tim, I just assumed I was using it wrong. > +#else /* CONFIG_PRINTK */ > +static inline int kunit_printk_emit(int level, const char *fmt, ...) > +{ > + return 0; > +} > +#endif /* CONFIG_PRINTK */ > > Does the following work? > > #if defined CONFIG_PRINTK > static int kunit_vprintk_emit(int level, const char *fmt, va_list args) > { > return vprintk_emit(0, level, NULL, 0, fmt, args); > } > #else > static int kunit_vprintk_emit(int level, const char *fmt, va_list args) > { > return 0; > } > #endif > > I think the real problem is in the printk.h with its missing define for > vprintk_emit() for !CONFIG_PRINTK case. There seem to only one call for > this in drivers/base/core.c in CONFIG_PRINTK path. Unless I am totally > missing some context for why there is no stub for vprintk_emit() for > !CONFIG_PRINTK case Agreed. Sorry again for the confusion. Thanks!
