From nobody Thu Apr 2 18:46:23 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C785A356A0B for ; Wed, 11 Feb 2026 22:32:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770849144; cv=none; b=VVK0/Wxwn9EyT05ukHnur9KoLompeH4EzgYl9ODjK3doimolaNbIuZjvwXI5YzokkbECIHpCvcxVwydL3O6Ls/i102u1TWqcrJ6Bbtey8twGM/irAQlCN8Ryh4UTNZGUbbcOAkEMwCqvDKrWi9pQt0snK/LUcihwV1zBgiYv6ZA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770849144; c=relaxed/simple; bh=s295lL6q8K8Ne/0PfNFhb/twpqM7r7QP3z2ozzUVaK0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uUduIXPnio7Hl/rT6y0nFU2NX1P/GVRz2ghjXVxofHvWJE3R8Cvc6iMpOPAdEKd0UO9z8ob7NncDMP26JPjAul97Qu4zsWSGwdqKcGmbZIDKpiCBjlK2rtNORdVFblZeimIaTN7fWDy1zjIHphPVPq4cyVHcdWK0cEahXD1UTSs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Mg4vgdHv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Mg4vgdHv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 502F1C2BC87; Wed, 11 Feb 2026 22:32:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770849144; bh=s295lL6q8K8Ne/0PfNFhb/twpqM7r7QP3z2ozzUVaK0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Mg4vgdHvcDsbdwiCFdda34V/XJE/MfJFRDj+BVBcj7eDJgU75grHtwH/HXfbtXh+f gOeYyZCA8r7ohjVS7ba2zHu8xezBX5tX51Wf4JoTt2HxkZ6RaA2FzZJwAM73khcsXP O3BBnvDe1TvVT2XosWSqnh7f4U02MJGqW7JFngQXnMN2LfvVRkuTOGYbRy1ag8H3E7 6MglqP9z8hOgB3rk6gh9DEtk3MQ/Wd5ZlAEc8VXk6Ma0EhbTTQPThLuIJk9XwBebhR bQKILu3ry6TeeCgXV5j+LorKBTI4um9CkEsD/o5ZAHlnVLPuX60GHUoE5aAhgMGYsE qdrVNLeMSh4Wg== From: Namhyung Kim To: Peter Zijlstra , Ingo Molnar Cc: Mark Rutland , Alexander Shishkin , Arnaldo Carvalho de Melo , LKML , Guenter Roeck Subject: [PATCH 3/3] perf/core: Simplify __detach_global_ctx_data() Date: Wed, 11 Feb 2026 14:32:21 -0800 Message-ID: <20260211223222.3119790-4-namhyung@kernel.org> X-Mailer: git-send-email 2.53.0.273.g2a3d683680-goog In-Reply-To: <20260211223222.3119790-1-namhyung@kernel.org> References: <20260211223222.3119790-1-namhyung@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Like in the attach_global_ctx_data() it has a O(N^2) loop to delete task context data for each thread. But perf_free_ctx_data_rcu() can be called under RCU read lock, so just calls it directly rather than iterating the whole thread list again. Signed-off-by: Namhyung Kim --- kernel/events/core.c | 15 ++++----------- 1 file changed, 4 insertions(+), 11 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 5b05a71edeb47955..e67e1baa99d1e5a9 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5561,22 +5561,15 @@ static void __detach_global_ctx_data(void) struct task_struct *g, *p; struct perf_ctx_data *cd; =20 -again: scoped_guard (rcu) { for_each_process_thread(g, p) { cd =3D rcu_dereference(p->perf_ctx_data); - if (!cd || !cd->global) - continue; - cd->global =3D 0; - get_task_struct(p); - goto detach; + if (cd && cd->global) { + cd->global =3D 0; + detach_task_ctx_data(p); + } } } - return; -detach: - detach_task_ctx_data(p); - put_task_struct(p); - goto again; } =20 static void detach_global_ctx_data(void) --=20 2.53.0.273.g2a3d683680-goog