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 C319D47F778; Fri, 25 Sep 2026 11:11:39 +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=1790334701; cv=none; b=dHNFA/+xuUg+tWVxUO7rwYSA0klUWM9cRtusy64gFJBSrBsVs+p2apfRtZ1H/y6SVDtSk4t64Mr0mTFQNaXqWuLuBbDKuqWuh+YJIu7bUbPmlN9OEml2R6mjcUelAQRf3kWiR0k1QvZuxvJClkLJnXs7JXy+KLDPzZgIOp2PNak= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790334701; c=relaxed/simple; bh=KGClkuKaUup4lCgi0hiMD2W62qNnYOQ5xSa3Rbyi+3U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=MztDp1HmGcuo8yVIYhh85FtfecAj+/H2HC2HQBgDv9eVCe/JeyjoU+VhfQCYMk1BtRUo1mgAiBmp9rGa2cIkvTEm9/MlgPnfg2mbtPVssp0W30ho6nI50U50WyufEtcw1aIOjFiFw3pYrCVJHYQQG6buKjbaLY2WUDDGVvoV8+U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UcQ8lQEy; 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="UcQ8lQEy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B07A1F000FF; Fri, 25 Sep 2026 11:11:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790334699; bh=7AfOVXhNr6aVAS93mjjDI1zHRc5gJSUYX5m1TeHMjbw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=UcQ8lQEyVJJseW0HcSUKhkWo7UXHZl5Kd253Eeky/jbi/l1ESUSi7MzSPvOdvQ8xA sU8NoSmHM8SgRyEp8wJD6c0rEpj4DPJWe1gxilagy3b6RRr5lMo5KZAo6epy36PoRC qAzncL0VFKpgLImY18w3QHCH3p294DIU9rbhK9tGeMCNNgWpPWtgEZ+OBkXmjrkXON AeON+IUgUIIaHgIl6FmObMzP/+Lb1TT5vw1p7c577omkRjdZQGmfmnrvUVvgbYiSYm Hqsa1hX/s0FEZCVmAmfE7jC6k4XEG1iKBx/eDbg0ZcrYWjksnV1ZRFVe7XsZ2pRn43 nl6xkLd9bGqDQ== 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 v18 03/11] perf/hw_breakpoint: Add register_wide_hw_breakpoint_cpuslocked() API Date: Fri, 25 Sep 2026 20:11:29 +0900 Message-ID: <179033468904.136630.17162448537904534428.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <179033464327.136630.864883694296882051.stgit@devnote2> References: <179033464327.136630.864883694296882051.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); /**