linux-kernel - Re: [PATCH] selftests/bpf: Add -Wsign-compare C compilation flag

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Message-ID: <581decf0-d360-4da8-a247-3b207d5ca21b@gmail.com>
Date: Wed, 1 Oct 2025 21:28:48 +0100
From: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>
To: Eduard Zingerman <eddyz87@...il.com>, andrii@...nel.org, ast@...nel.org,
 daniel@...earbox.net, martin.lau@...ux.dev, song@...nel.org,
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Cc: bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
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Subject: Re: [PATCH] selftests/bpf: Add -Wsign-compare C compilation flag

On 10/1/25 9:23 PM, Eduard Zingerman wrote:
> On Wed, 2025-09-24 at 17:23 +0100, Mehdi Ben Hadj Khelifa wrote:
>> -Change all the source files and the corresponding headers
>> to having matching sign comparisons.
>>
>> Signed-off-by: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>
>> ---
>> As suggested by the TODO, -Wsign-compare was added to the C compilation
>> flags for the selftests/bpf/Makefile and all corresponding files in
>> selftests and a single file under tools/lib/bpf/usdt.bpf.h have been
>> carefully changed to account for correct sign comparisons either by
>> explicit casting or changing the variable type.Only local variables
>> and variables which are in limited scope have been changed in cases
>> where it doesn't break the code.Other struct variables or global ones
>> have left untouched to avoid other conflicts and opted to explicit
>> casting in this case.This change will help avoid implicit type
>> conversions and have predictable behavior.
>>
>> I have already compiled all bpf tests with no errors as well as the
>> kernel and have ran all the selftests with no obvious side effects.
>> I would like to know if it's more convinient to have all changes as
>> a single patch like here or if it needs to be divided in some way
>> and sent as a patch series.
>>
>> Best Regards,
>> Mehdi Ben Hadj Khelifa
>> ---
> 
> I don't understand why this change is necessary.
> Have you found any bugs while doing this conversion?
> 
> [...]

Hi Eduard,
No I have not. It's more of a future proof patch / improvement rather 
than a fixing patch as i mentioned in this email[1] with more detail.
Regards,
Mehdi
[1]:https://lore.kernel.org/all/e3a0d8ff-d03d-4854-bf04-8ff8265b0257@gmail.com/