On Fri, Mar 28, 2025 at 04:44:53AM -0600, Simon Glass wrote:
> Hi Tom,
>
> On Thu, 27 Mar 2025 at 17:50, Tom Rini <tr...@konsulko.com> wrote:
> >
> > On Wed, Mar 26, 2025 at 10:46:57AM -0600, Simon Glass wrote:
> > > Hi Quentin,
> > >
> > > On Tue, 25 Mar 2025 at 04:20, Quentin Schulz <quentin.sch...@cherry.de>
> > > wrote:
> > > >
> > > > Hi Simon,
> > > >
> > > > On 3/20/25 4:26 AM, Simon Glass wrote:
> > > > > Hi Quentin,
> > > > >
> > > > > On Wed, 19 Mar 2025 at 16:31, Quentin Schulz
> > > > > <quentin.sch...@cherry.de> wrote:
> > > > >>
> > > > >> Hi Simon
> > > > >>
> > > > >> On 3/19/25 4:03 PM, Simon Glass wrote:
> > > > >>> Hi Quentin,
> > > > >>>
> > > > >>> On Wed, 19 Mar 2025 at 13:04, Quentin Schulz
> > > > >>> <quentin.sch...@cherry.de> wrote:
> > > > >>>>
> > > > >>>> Hi Simon,
> > > > >>>>
> > > > >>>> On 3/19/25 12:49 PM, Simon Glass wrote:
> > > > >>>>> Logging of function return-values is used very frequently in
> > > > >>>>> U-Boot now.
> > > > >>>>> Add a few helper macros to make it less verbose to use.
> > > > >>>>>
> > > > >>>>> It turns out that the log_ret() variants are not so useful, since
> > > > >>>>> it is
> > > > >>>>> not obviously where the error is coming from. So only the
> > > > >>>>> log_msg_ret()
> > > > >>>>> variants are worthy of these macros.
> > > > >>>>>
> > > > >>>>> Signed-off-by: Simon Glass <s...@chromium.org>
> > > > >>>>> ---
> > > > >>>>>
> > > > >>>>> include/log.h | 26 ++++++++++++++++++++++++++
> > > > >>>>> 1 file changed, 26 insertions(+)
> > > > >>>>>
> > > > >>>>> diff --git a/include/log.h b/include/log.h
> > > > >>>>> index 4f6d6a2c2cf..bdda7af570c 100644
> > > > >>>>> --- a/include/log.h
> > > > >>>>> +++ b/include/log.h
> > > > >>>>> @@ -380,6 +380,32 @@ void __assert_fail(const char *assertion,
> > > > >>>>> const char *file, unsigned int line,
> > > > >>>>> #define log_msg_retz(_msg, _ret) ((void)(_msg), _ret)
> > > > >>>>> #endif
> > > > >>>>>
> > > > >>>>> +/*
> > > > >>>>> + * LOGR() - helper macro for calling a function and logging
> > > > >>>>> error returns
> > > > >>>>> + *
> > > > >>>>> + * Logs if the function returns a negative value
> > > > >>>>> + *
> > > > >>>>> + * Usage: LOGR("abc", my_function(...));
> > > > >>>>> + */
> > > > >>>>> +#define LOGR(_msg, _expr) do { \
> > > > >>>>> + int _ret = _expr; \
> > > > >>>>> + if (_ret < 0) \
> > > > >>>>> + return log_msg_ret(_msg, _ret); \
> > > > >>>>> + } while (0)
> > > > >>>>> +
> > > > >>>>> +/*
> > > > >>>>> + * LOGZ() - helper macro for calling a function and logging
> > > > >>>>> error returns
> > > > >>>>> + *
> > > > >>>>> + * Logs if the function returns a non-zero value
> > > > >>>>> + *
> > > > >>>>> + * Usage: LOGZ("abc", my_function(...));
> > > > >>>>> + */
> > > > >>>>> +#define LOGZ(_msg, _expr) do { \
> > > > >>>>> + int _ret = _expr; \
> > > > >>>>> + if (_ret) \
> > > > >>>>> + return log_msg_retz(_msg, _ret); \
> > > > >>>>> + } while (0)
> > > > >>>>> +
> > > > >>>>
> > > > >>>> Mmmm not sure this forced return call is a good idea, this would
> > > > >>>> forbid
> > > > >>>> us from performing some unwinding for example.
> > > > >>>
> > > > >>> Yes, it is really only for simple cases. Without the return, there
> > > > >>> isn't much value and you may as well not use this macro.
> > > > >>>
> > > > >>>>
> > > > >>>> I don't really see how that is better than simply calling
> > > > >>>>
> > > > >>>> return log_msg_retz("abc", my_function());
> > > > >>>
> > > > >>> That's not the intention. It actually replaces:
> > > > >>>
> > > > >>> ret = my_function();
> > > > >>> if (ret)
> > > > >>> return_log_msg_ret("abc", ret);
> > > > >>>
> > > > >>> I use this a lot in my code. You can't always just return, since
> > > > >>> there
> > > > >>> may not be an error.
> > > > >>>
> > > > >>
> > > > >> I see, I read too fast again. Only return if it's an error.
> > > > >>
> > > > >>>>
> > > > >>>> ?
> > > > >>>>
> > > > >>>> If we were to keep this, I would recommend to rename the macro and
> > > > >>>> fix
> > > > >>>> the docstring because it does not only log if the function returns
> > > > >>>> a
> > > > >>>> non-zero value. It does actually return.
> > > > >>>>
> > > > >>>> So something like
> > > > >>>>
> > > > >>>> LOGZ_AND_RETURN(_msg, _expr)
> > > > >>>>
> > > > >>>> maybe?
> > > > >>>
> > > > >>> Sure, longer names are easier to learn, but then it is so long I
> > > > >>> doubt
> > > > >>> anyone would use it.
> > > > >>>
> > > > >>> Perhaps LOG_RET() and LOG_RETZ() ? But they might get confused with
> > > > >>> log_ret() and log_retz(), which I am actually thinking of deleting.
> > > > >>>
> > > > >>> I would like the shortest possible name to avoid spilling functions
> > > > >>> onto the next line all the time.
> > > > >>>
> > > > >>
> > > > >> It should be absolutely obvious from the macro name that this can in
> > > > >> fact return because missing to unwind code is among the things
> > > > >> developers typically easily miss already, so with this macro it'll be
> > > > >> even easier to forget about undoing things.
> > > > >>
> > > > >
> > > > > Yes that's true. We don't have a huge amount of tests for this 'undo'
> > > > > code either. I would bet that a code-coverage map would show that.
> > > > >
> > > >
> > > > Yeah but that's not a reason to make it even harder to spot issues in
> > > > the undo code :)
> > >
> > > I suspect people will just have to learn the macros, as they have with
> >
> > I would ask "What kernel construct have people already learned and we
> > can adapt inside the macro?".
>
> Is there such a thing?Likely so. This isn't some new and novel problem, and it's likely more people have put thought in to this and come up with something well reviewed there. -- Tom
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