From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 EC64A38AC7E; Sat, 3 Oct 2026 07:52:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791013977; cv=none; b=m3952xnHfSLo+mVnAcR5Kse19yfjI7tub0cA+6hjByBoNABOy7tnGQLgbqkaXGWHJU/KoYXdCtQ2wBHdcVfDSPUmwTj+v8pNXzVr5QAAwdUPR3u/kk2fsTgyATzG3g+ZnYWIWvAwYbPJhlBccXV7reM6tUygo/qYvAs2OU/n6mQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791013977; c=relaxed/simple; bh=KGClkuKaUup4lCgi0hiMD2W62qNnYOQ5xSa3Rbyi+3U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=HYIDYnNbbvGyLstHxEZAy+zOFZyoucmpQNBJxLYY7RshbycRAE6f4GzxfLwQl98lXwfUk1Vzv7WFYE+amn1i68rbdVlp/BH6k+OLXBpHsFJHCRDR8aJUi53fArZQaYHfWSqMJoB1Ijpw9PauQcTwAOem5fw8EgVVuG+Lg3R8CqI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Q2K+iLuW; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Q2K+iLuW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B18071F0089B; Sat, 3 Oct 2026 07:52:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791013975; bh=7AfOVXhNr6aVAS93mjjDI1zHRc5gJSUYX5m1TeHMjbw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Q2K+iLuWCcu8LKT/4ysXhgkBg5FP6wqTzgptpjcxTgWntvdg9ueamNUoNl6x7AkzR /wQGMnXZQsEDxsQxHqw9HSuBCJUV+FoYqGQ8b8p4UIrYLxrNqmxcu/OZsKMSwSDnxU 7jkgpcbbqHUlJQFduVVyzTRi243i8Ld+hyERnpuBIG2EevRiA9LLk42pwj3aR2e8OS neMNIRpU0+R7guQJH8q5Jb/CAtP+JjDLNMFQ6FCdvX9f6cSV7amln/Gb87XZmtxo/b K69nY01PbXciPx9SRNQpCYXQA7pem/95ZkzlLas5TdBRCSypNVTVxHzPcCFQt4heE4 JHa24j7RiYpew== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Peter Zijlstra , Ingo Molnar Cc: Jinchao Wang , Mathieu Desnoyers , Masami Hiramatsu , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org, x86@kernel.org Subject: [PATCH v19 03/11] perf/hw_breakpoint: Add register_wide_hw_breakpoint_cpuslocked() API Date: Sat, 3 Oct 2026 16:52:49 +0900 Message-ID: <179101396937.22872.545144610777427663.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <179101393469.22872.5895666191299551553.stgit@devnote2> References: <179101393469.22872.5895666191299551553.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit From: Masami Hiramatsu (Google) Add register_wide_hw_breakpoint_cpuslocked() which registers a wide hardware breakpoint across all online CPUs while caller holds cpus_read_lock(). This allows callers who need to perform additional setup under cpus_read_lock() without releasing it to avoid races with CPU hotplug and without triggering recursive lockdep warnings. Refactor register_wide_hw_breakpoint() as a wrapper around register_wide_hw_breakpoint_cpuslocked(). Assisted-by: LLM Signed-off-by: Masami Hiramatsu (Google) --- include/linux/hw_breakpoint.h | 9 +++++++++ kernel/events/hw_breakpoint.c | 38 ++++++++++++++++++++++++++++++++------ 2 files changed, 41 insertions(+), 6 deletions(-) diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h index bf65c7fffd99..65efe55fef14 100644 --- a/include/linux/hw_breakpoint.h +++ b/include/linux/hw_breakpoint.h @@ -76,6 +76,11 @@ register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr, void *context, int cpu); +extern struct perf_event * __percpu * +register_wide_hw_breakpoint_cpuslocked(struct perf_event_attr *attr, + perf_overflow_handler_t triggered, + void *context); + extern struct perf_event * __percpu * register_wide_hw_breakpoint(struct perf_event_attr *attr, perf_overflow_handler_t triggered, @@ -123,6 +128,10 @@ register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr, void *context, int cpu) { return NULL; } static inline struct perf_event * __percpu * +register_wide_hw_breakpoint_cpuslocked(struct perf_event_attr *attr, + perf_overflow_handler_t triggered, + void *context) { return NULL; } +static inline struct perf_event * __percpu * register_wide_hw_breakpoint(struct perf_event_attr *attr, perf_overflow_handler_t triggered, void *context) { return NULL; } diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index 69bfb17b87c4..5627ad97600a 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -832,27 +832,30 @@ void unregister_hw_breakpoint(struct perf_event *bp) EXPORT_SYMBOL_GPL(unregister_hw_breakpoint); /** - * register_wide_hw_breakpoint - register a wide breakpoint in the kernel + * register_wide_hw_breakpoint_cpuslocked - register a wide breakpoint with cpus locked * @attr: breakpoint attributes * @triggered: callback to trigger when we hit the breakpoint * @context: context data could be used in the triggered callback * + * Same as register_wide_hw_breakpoint(), but caller must hold cpus_read_lock(). + * * @return a set of per_cpu pointers to perf events */ struct perf_event * __percpu * -register_wide_hw_breakpoint(struct perf_event_attr *attr, - perf_overflow_handler_t triggered, - void *context) +register_wide_hw_breakpoint_cpuslocked(struct perf_event_attr *attr, + perf_overflow_handler_t triggered, + void *context) { struct perf_event * __percpu *cpu_events, *bp; long err = 0; int cpu; + lockdep_assert_cpus_held(); + cpu_events = alloc_percpu(typeof(*cpu_events)); if (!cpu_events) return ERR_PTR_PCPU(-ENOMEM); - cpus_read_lock(); for_each_online_cpu(cpu) { bp = perf_event_create_kernel_counter(attr, cpu, NULL, triggered, context); @@ -863,7 +866,6 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr, per_cpu(*cpu_events, cpu) = bp; } - cpus_read_unlock(); if (likely(!err)) return cpu_events; @@ -871,6 +873,30 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr, unregister_wide_hw_breakpoint(cpu_events); return ERR_PTR_PCPU(err); } +EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint_cpuslocked); + +/** + * register_wide_hw_breakpoint - register a wide breakpoint in the kernel + * @attr: breakpoint attributes + * @triggered: callback to trigger when we hit the breakpoint + * @context: context data could be used in the triggered callback + * + * @return a set of per_cpu pointers to perf events + */ +struct perf_event * __percpu * +register_wide_hw_breakpoint(struct perf_event_attr *attr, + perf_overflow_handler_t triggered, + void *context) +{ + struct perf_event * __percpu *cpu_events; + + cpus_read_lock(); + cpu_events = register_wide_hw_breakpoint_cpuslocked(attr, triggered, + context); + cpus_read_unlock(); + + return cpu_events; +} EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint); /**