linux-kernel - Re: [PATCH v3 1/3] drm/amd/display: Add ASSERT

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Message-ID: <1d34d05c-d408-4ee3-c385-f9367b7c3be5@loongson.cn>
Date: Tue, 14 Jan 2025 19:52:20 +0800
From: Tiezhu Yang <yangtiezhu@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: Alex Deucher <alexander.deucher@....com>,
 Christian König <christian.koenig@....com>,
 Xinhui Pan <Xinhui.Pan@....com>, Harry Wentland <harry.wentland@....com>,
 Leo Li <sunpeng.li@....com>, Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
 Nathan Chancellor <nathan@...nel.org>, Josh Poimboeuf <jpoimboe@...nel.org>,
 Peter Zijlstra <peterz@...radead.org>, loongarch@...ts.linux.dev,
 amd-gfx@...ts.freedesktop.org, llvm@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/3] drm/amd/display: Add ASSERT_BUG() macro definition

On 01/14/2025 04:29 PM, Huacai Chen wrote:
> Hi, Tiezhu,
>
> On Tue, Jan 14, 2025 at 2:16 PM Tiezhu Yang <yangtiezhu@...ngson.cn> wrote:
>>
>> In order to keep the current ability for the aim of debugging and avoid
>> printing the warning message twice, add ASSERT_BUG() macro definition to
>> harden the callers of division functions.
>>
>> Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
>> ---
>>  drivers/gpu/drm/amd/display/dc/os_types.h | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/amd/display/dc/os_types.h b/drivers/gpu/drm/amd/display/dc/os_types.h
>> index f2ba76c1e0c0..932bbe05ee0a 100644
>> --- a/drivers/gpu/drm/amd/display/dc/os_types.h
>> +++ b/drivers/gpu/drm/amd/display/dc/os_types.h
>> @@ -79,6 +79,11 @@
>>                         dc_breakpoint();        \
>>         } while (0)
>>
>> +#define ASSERT_BUG(expr) do {                  \
>> +               dc_breakpoint();                \
>> +               BUG_ON(!(expr));                \
>> +       } while (0)
> I don't think this is correct, if KGDB is enabled, then whether expr
> is true or false, ASSERT_BUG() will break to KGDB.

It should check expr first, something like this:

#define ASSERT_BUG(expr) do {                   \
                 if (!(expr)) {                  \
                         dc_breakpoint();        \
                         BUG();                  \
                 }                               \
         } while (0)

I will send v4 later.

Thanks,
Tiezhu