From nobody Mon Dec 1 23:36:43 2025 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 12F7A3128A9; Wed, 26 Nov 2025 04:36:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764131781; cv=none; b=MTdqAQxHs7fgWv0lHHxe78Y7lpFrSAhf/Vqi12HnBXm0V4trhdVLE5jpxHXCoPXQBgCl5IzOxGw4n7zwk3vvUR284Zas+zOsPyul1BY6FMO0kiLh0a+pO+YSKxJlXAqlfY8kFKJ1jAK8zhkPIX2ATATNDuAdrCT7fEV35fBlEmg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764131781; c=relaxed/simple; bh=fnoDJXaDSOCeI7NPsxgouHx7Hs97To+mxSZHlmgHiDs=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=m5gGiPXxTWcOuM7GTB6pub0Olt1zyFzLx6egyI6V6XhEUj1o2SZ9ttfPh4DAeQH0SUdP3R3Flh7ZyAeuSs/JsVHQXa6KrTmMsQ7zgCeVN5k79pBmkBozt4BLZ+m+5OS1c/nyCyu5nbpuS8+IkBvLOjH2N48sojaera1XE2H05wo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=K8tCDvww; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=LAlc6rdA; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="K8tCDvww"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="LAlc6rdA" Date: Wed, 26 Nov 2025 04:36:16 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1764131777; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Tnz0md2X20d3tzGa0poevVtw1UzAg8qevBsY2fhfHew=; b=K8tCDvwwbmxX/dOb6vYAF18n4cqzdb7mLi2PyMKF9lcUgKjrvlNmooyXm5N9RoljMP4a3M F8hWdPSVFIDFjejC0oA49IOKLK2mACeUq8S1sIShQRFlF2t45WWinpWKKcvkT91cAqwwLn vimyXVQOy+LHIDFtJSCG/2VW1A6ctnZPDzckS4I2kLnpjBh1lK3+oPDqXC6po8CZz2AuGO F1E9A3g/IE91j0GyWPzPHK/2Mk8i1FJCbdNB0UWqzrxkmdCvsU6VqrElR7xQzn9yGpNPID DvdUG2KBWyuaS+KvGs1dXLgFfC60OzV2Q9eokfLBblAfqt8Ij2xUPSLy+EW9Dw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1764131777; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Tnz0md2X20d3tzGa0poevVtw1UzAg8qevBsY2fhfHew=; b=LAlc6rdAF/Y6yNRFAhuP+Q9DjGVKGTHcV1trPB+FkyZisbMq/cQwjmkpr7Hhu+qXkh53+c NxepjWuCSb85JJAw== From: "tip-bot2 for Thomas Gleixner" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: core/rseq] cpumask: Cache num_possible_cpus() Cc: Thomas Gleixner , "Peter Zijlstra (Intel)" , Yury Norov , Mathieu Desnoyers , Shrikanth Hegde , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20251119172549.578653738@linutronix.de> References: <20251119172549.578653738@linutronix.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <176413177658.498.8348323122345597622.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the core/rseq branch of tip: Commit-ID: 35a5c37cb9f1f947dff18e7cfc75a8cfcfd557ca Gitweb: https://git.kernel.org/tip/35a5c37cb9f1f947dff18e7cfc75a8cfc= fd557ca Author: Thomas Gleixner AuthorDate: Wed, 19 Nov 2025 18:27:01 +01:00 Committer: Thomas Gleixner CommitterDate: Tue, 25 Nov 2025 19:45:40 +01:00 cpumask: Cache num_possible_cpus() Reevaluating num_possible_cpus() over and over does not make sense. That becomes a constant after init as cpu_possible_mask is marked ro_after_init. Cache the value during initialization and provide that for consumption. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Reviewed-by: Yury Norov Reviewed-by: Mathieu Desnoyers Reviewed-by: Shrikanth Hegde Link: https://patch.msgid.link/20251119172549.578653738@linutronix.de --- include/linux/cpumask.h | 10 ++++++++-- kernel/cpu.c | 19 +++++++++++++++++++ 2 files changed, 27 insertions(+), 2 deletions(-) diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index feba06e..66694ee 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -126,6 +126,7 @@ extern struct cpumask __cpu_dying_mask; #define cpu_dying_mask ((const struct cpumask *)&__cpu_dying_mask) =20 extern atomic_t __num_online_cpus; +extern unsigned int __num_possible_cpus; =20 extern cpumask_t cpus_booted_once_mask; =20 @@ -1152,13 +1153,13 @@ void init_cpu_possible(const struct cpumask *src); #define __assign_cpu(cpu, mask, val) \ __assign_bit(cpumask_check(cpu), cpumask_bits(mask), (val)) =20 -#define set_cpu_possible(cpu, possible) assign_cpu((cpu), &__cpu_possible_= mask, (possible)) #define set_cpu_enabled(cpu, enabled) assign_cpu((cpu), &__cpu_enabled_mas= k, (enabled)) #define set_cpu_present(cpu, present) assign_cpu((cpu), &__cpu_present_mas= k, (present)) #define set_cpu_active(cpu, active) assign_cpu((cpu), &__cpu_active_mask, = (active)) #define set_cpu_dying(cpu, dying) assign_cpu((cpu), &__cpu_dying_mask, (dy= ing)) =20 void set_cpu_online(unsigned int cpu, bool online); +void set_cpu_possible(unsigned int cpu, bool possible); =20 /** * to_cpumask - convert a NR_CPUS bitmap to a struct cpumask * @@ -1211,7 +1212,12 @@ static __always_inline unsigned int num_online_cpus(= void) { return raw_atomic_read(&__num_online_cpus); } -#define num_possible_cpus() cpumask_weight(cpu_possible_mask) + +static __always_inline unsigned int num_possible_cpus(void) +{ + return __num_possible_cpus; +} + #define num_enabled_cpus() cpumask_weight(cpu_enabled_mask) #define num_present_cpus() cpumask_weight(cpu_present_mask) #define num_active_cpus() cpumask_weight(cpu_active_mask) diff --git a/kernel/cpu.c b/kernel/cpu.c index db9f6c5..b674fdf 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -3085,10 +3085,13 @@ EXPORT_SYMBOL(cpu_all_bits); #ifdef CONFIG_INIT_ALL_POSSIBLE struct cpumask __cpu_possible_mask __ro_after_init =3D {CPU_BITS_ALL}; +unsigned int __num_possible_cpus __ro_after_init =3D NR_CPUS; #else struct cpumask __cpu_possible_mask __ro_after_init; +unsigned int __num_possible_cpus __ro_after_init; #endif EXPORT_SYMBOL(__cpu_possible_mask); +EXPORT_SYMBOL(__num_possible_cpus); =20 struct cpumask __cpu_online_mask __read_mostly; EXPORT_SYMBOL(__cpu_online_mask); @@ -3116,6 +3119,7 @@ void init_cpu_present(const struct cpumask *src) void init_cpu_possible(const struct cpumask *src) { cpumask_copy(&__cpu_possible_mask, src); + __num_possible_cpus =3D cpumask_weight(&__cpu_possible_mask); } =20 void set_cpu_online(unsigned int cpu, bool online) @@ -3140,6 +3144,21 @@ void set_cpu_online(unsigned int cpu, bool online) } =20 /* + * This should be marked __init, but there is a boatload of call sites + * which need to be fixed up to do so. Sigh... + */ +void set_cpu_possible(unsigned int cpu, bool possible) +{ + if (possible) { + if (!cpumask_test_and_set_cpu(cpu, &__cpu_possible_mask)) + __num_possible_cpus++; + } else { + if (cpumask_test_and_clear_cpu(cpu, &__cpu_possible_mask)) + __num_possible_cpus--; + } +} + +/* * Activate the first processor. */ void __init boot_cpu_init(void)