From: Yonghong Song <yonghong.song@linux.dev>
To: Tao Chen <chen.dylane@linux.dev>,
peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
namhyung@kernel.org, mark.rutland@arm.com,
alexander.shishkin@linux.intel.com, jolsa@kernel.org,
irogers@google.com, adrian.hunter@intel.com,
kan.liang@linux.intel.com
Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
bpf@vger.kernel.org
Subject: Re: [PATCH bpf-next v6 2/2] bpf: Hold the perf callchain entry until used completely
Date: Thu, 13 Nov 2025 08:01:38 -0800 [thread overview]
Message-ID: <c41372ad-1591-4f2b-a786-bc0e19f8425c@linux.dev> (raw)
In-Reply-To: <20251112163148.100949-3-chen.dylane@linux.dev>
On 11/12/25 8:31 AM, Tao Chen wrote:
> As Alexei noted, get_perf_callchain() return values may be reused
> if a task is preempted after the BPF program enters migrate disable
> mode. The perf_callchain_entres has a small stack of entries, and
> we can reuse it as follows:
>
> 1. get the perf callchain entry
> 2. BPF use...
> 3. put the perf callchain entry
>
> And Peter suggested that get_recursion_context used with preemption
> disabled, so we should disable preemption at BPF side.
>
> Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
next prev parent reply other threads:[~2025-11-13 16:02 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-12 16:31 [PATCH bpf-next v6 0/2] Pass external callchain entry to get_perf_callchain Tao Chen
2025-11-12 16:31 ` [PATCH bpf-next v6 1/2] perf: Refactor get_perf_callchain Tao Chen
2025-11-12 16:31 ` [PATCH bpf-next v6 2/2] bpf: Hold the perf callchain entry until used completely Tao Chen
2025-11-13 16:01 ` Yonghong Song [this message]
2025-11-26 9:29 ` Tao Chen
2025-12-03 9:33 ` Tao Chen
2025-12-16 23:35 ` Alexei Starovoitov
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