linux-kernel - Re: [RFC PATCH bpf-next v2 2/2] bpf: Pass external callchain entry to get_perf

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Message-ID: <da9d29d1-ecfe-4d0a-8e13-aa13f0620d0f@linux.dev>
Date: Tue, 14 Oct 2025 20:34:51 +0800
From: Tao Chen <chen.dylane@...ux.dev>
To: Jiri Olsa <olsajiri@...il.com>
Cc: peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
 namhyung@...nel.org, mark.rutland@....com,
 alexander.shishkin@...ux.intel.com, irogers@...gle.com,
 adrian.hunter@...el.com, kan.liang@...ux.intel.com, song@...nel.org,
 ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
 martin.lau@...ux.dev, eddyz87@...il.com, yonghong.song@...ux.dev,
 john.fastabend@...il.com, kpsingh@...nel.org, sdf@...ichev.me,
 haoluo@...gle.com, linux-perf-users@...r.kernel.org,
 linux-kernel@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [RFC PATCH bpf-next v2 2/2] bpf: Pass external callchain entry to
 get_perf_callchain

在 2025/10/14 20:14, Jiri Olsa 写道:
>> +	struct bpf_perf_callchain_entry entry = { 0 };
> so IIUC having entries on stack we do not need to do preempt_disable
> you had in the previous version, right?
> 

Yes, i think so, preempt_disable seems unnecessary.

> I saw Andrii's justification to have this on the stack, I think it's
> fine, but does it have to be initialized? it seems that only used
> entries are copied to map

That makes sense. Removing it definitely looks better.

-- 
Best Regards
Tao Chen