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Re: [PATCH-for-8.0] coroutine: Add missing <qemu/atomic.h> include
From: |
Markus Armbruster |
Subject: |
Re: [PATCH-for-8.0] coroutine: Add missing <qemu/atomic.h> include |
Date: |
Wed, 14 Dec 2022 15:11:01 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) |
Philippe Mathieu-Daudé <philmd@linaro.org> writes:
> On 14/12/22 08:58, Markus Armbruster wrote:
>> Philippe Mathieu-Daudé <philmd@linaro.org> writes:
>>
>>> qemu_co_mutex_assert_locked() calls qatomic_read(), which
>>> is declared in <qemu/atomic.h>. This fixes when refactoring:
>>>
>>> In file included from include/qemu/osdep.h:113,
>>> from ../../util/error-report.c:13:
>>> include/qemu/coroutine.h: In function 'qemu_co_mutex_assert_locked':
>>> include/qemu/coroutine.h:182:12: error: implicit declaration of function
>>> 'qatomic_read' [-Werror=implicit-function-declaration]
>>> 182 | assert(qatomic_read(&mutex->locked) &&
>>> | ^~~~~~~~~~~~
>>>
>>> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
>>> ---
>>> include/qemu/coroutine.h | 1 +
>>> 1 file changed, 1 insertion(+)
>>>
>>> diff --git a/include/qemu/coroutine.h b/include/qemu/coroutine.h
>>> index 89650a2d7f..1750c30d8e 100644
>>> --- a/include/qemu/coroutine.h
>>> +++ b/include/qemu/coroutine.h
>>> @@ -17,6 +17,7 @@
>>> #include "qemu/queue.h"
>>> #include "qemu/timer.h"
>>> +#include "qemu/atomic.h"
>>> /**
>>> * Coroutines are a mechanism for stack switching and can be used for
>> I think this papers over the actual problem.
>> Compiling qemu/coroutine.h by itself succeeds for me. Printing headers
>> with -H shows:
>> [osdep.h and everything it includes elided...]
>> . ../include/qemu/coroutine.h
>> .. /work/armbru/qemu/include/qemu/queue.h
>> .. /work/armbru/qemu/include/qemu/timer.h
>> ... /work/armbru/qemu/include/qemu/bitops.h
>> .... /work/armbru/qemu/include/qemu/host-utils.h
>> ..... /work/armbru/qemu/include/qemu/bswap.h
>> ...... /usr/include/byteswap.h
>> ....... /usr/include/bits/byteswap.h
>> ..... /work/armbru/qemu/include/qemu/int128.h
>> .... /work/armbru/qemu/include/qemu/atomic.h
>> [more...]
>> So, qemu/coroutine.h *already* includes qemu/atomic.h, via qemu/timer.h
>> and qemu/bitops.h.
>
> Well I'm not sure this implicit dependency is correct, since "coroutine.h"
> explicitly access a function declared in "atomic.h";
> if I want to modify "qemu/timer.h" or "qemu/bitops.h" I'm back to
> this very patch.
We have a rule "every header should include everything it needs". We
don't have a rule "every header should include everything it needs
directly".
Yes, this means that when you drop includes from a header, you may have
to add them back elsewhere.
>> I suspect the actual problem is an inclusion loop: qemu/coroutine.h and
>> qemu/lockable.h include each other. See my
>> Subject: [PATCH 4/4] coroutine: Break inclusion loop
>> Message-Id: <20221208142306.2642640-5-armbru@redhat.com>
>> and Paolo's review.
>
> So I guess I'll wait your series to get merged and see what happens
> when I rebase my work on yours.
Makes sense to me.