From nobody Wed Nov 27 14:38:38 2024 Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9CC5E149C4F for ; Wed, 9 Oct 2024 23:54:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728518047; cv=none; b=k3tcnO/bBeBpiZpUwAy3S/Wrgacqhuhh2PxD8vFgZpvlYUDo0XCbG7xX4IrDseUUBRT4e65CWWAvPqEryMWJ+gARcSyslo++WJG7iVsmRXA97yU9j89gHn7Xgc1ijunPPTJHYhU/LjdwR2Fd9QWcavahxc0aYB/1UycBIOih6Ao= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728518047; c=relaxed/simple; bh=wqY14AU+JSwok0UwEF/K9zE/dL8T0OKEFy+eP0e6QlU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=qRoo14aNiQHZ9fZ+3RaHHCyW/WI77hXdcYRkcJumS4N40vTM3qRrq4Nk51xjijaji5xz6eAt+JveT30TYfXclRel74QpnNZEuw+XuW+snW0GQlVrJxMXCv8NdOljKwjvc45ONlOC8A3bYPKFdalAbPrMgAqzW9Qc0oe09mBIXD0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--jstultz.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=IF1cR3ir; arc=none smtp.client-ip=209.85.219.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--jstultz.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="IF1cR3ir" Received: by mail-yb1-f201.google.com with SMTP id 3f1490d57ef6-e2904a54a10so462642276.3 for ; Wed, 09 Oct 2024 16:54:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1728518044; x=1729122844; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=CkogdeMtbJj9ox/OqjcbeCQ27hEpo9k2fOdRUr04kJg=; b=IF1cR3irF50m8fJcxHC2XNlqv6djdWsYWgWj9CirBlQuy66k03JKA8O0mkBdlepMVS xWRhsP6URWeW1/3nGMis6xXO2oeq4Fvn/rg9SBlbViLd1OQ5jPRCUqSLrpu2zQwyL3Tv SbgVAxqO8a/t+YKeCH3D7p/AOfuju5Kc/fgHHz6YZbEW+aL9wnLfGuDreJQlvxnbOhLw N3kWl5uWIsqf3WKTLZ5QovgOM6QTZF/fkv9nBr56c7nRdeluRsvu+8v6fGGGfhWoTxYS ej4CYTlKWAHdxPM5UnCfpLttKKzX8il3ut/XyEfwnMLOOwYWvANfM4ovZtMXnxHh69yV wQQQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1728518044; x=1729122844; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=CkogdeMtbJj9ox/OqjcbeCQ27hEpo9k2fOdRUr04kJg=; b=r3pL1TNwBMSLSLHM2shqY4jpCQq+bBd66GDUPOWBpGW+Pmnz14DiHt4GmQuKRhAPtm 2nICe3X8rE2p+IMS8hkwhctR28HSpl3ZQgGpTg969ow33Dh6E+9yvqku1QTAVGopZ226 UtS/AboIJ98BDk/ydSU0tetazan9O8t38u+ur1kPGiwLJAdJMI3emehhT9wf1/e3fRm7 QAD2LiiWeYIW2oB74uJ6j+v8PmhFZpOD+ZUdl/Jfa+TU5C6/zsBw4Y0fD6pUCVRrT0bW ezpAf6T5LbMzD+bZRsAuKuO6TscAS+kL+i7I32ZiMYCMpEy+qIFe9gRJ9oT3V4YNNG0q 5sFQ== X-Gm-Message-State: AOJu0Yx3iTyYllkz7fuQPAlo1M+Bv+d13YsJyad7xKLB2WeJKOSeSQCI IPbt56h0bKOKes7Y8sIoizVLjgM1FmRv5lRO7CixCEDSKM0Eg0w0O7rhYp8bNhvEGGuIR+aw7xw wi2mPIEfrERZQ6V3IRNf5mXW7stVqliVAu+8OKE5RWB3ahKZKcCiUCPUUE39zIqvtvEK4E0DBwl A04poNQ2JlPhgsfaZeYlWJbokSidzLqJFNIMikGtXIHAiD X-Google-Smtp-Source: AGHT+IGubb1i6Fe4d1tNJZZWfjTqMmvikGKS3I8RQwQIBtaDowV7huq0tOvyvN/FAU/Qkd6pvEsYusKzWfH5 X-Received: from jstultz-noogler2.c.googlers.com ([fda3:e722:ac3:cc00:24:72f4:c0a8:600]) (user=jstultz job=sendgmr) by 2002:a25:c74a:0:b0:e25:cea9:b0e with SMTP id 3f1490d57ef6-e28fe54b2f9mr2895276.9.1728518044054; Wed, 09 Oct 2024 16:54:04 -0700 (PDT) Date: Wed, 9 Oct 2024 16:53:36 -0700 In-Reply-To: <20241009235352.1614323-1-jstultz@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241009235352.1614323-1-jstultz@google.com> X-Mailer: git-send-email 2.47.0.rc0.187.ge670bccf7e-goog Message-ID: <20241009235352.1614323-4-jstultz@google.com> Subject: [RESEND x3][PATCH v12 3/7] locking/mutex: Expose __mutex_owner() From: John Stultz To: LKML Cc: Juri Lelli , Joel Fernandes , Qais Yousef , Ingo Molnar , Peter Zijlstra , Vincent Guittot , Dietmar Eggemann , Valentin Schneider , Steven Rostedt , Ben Segall , Zimuzo Ezeozue , Mel Gorman , Will Deacon , Waiman Long , Boqun Feng , "Paul E. McKenney" , Metin Kaya , Xuewen Yan , K Prateek Nayak , Thomas Gleixner , Daniel Lezcano , kernel-team@android.com, Metin Kaya , Valentin Schneider , "Connor O'Brien" , John Stultz Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Juri Lelli Implementing proxy execution requires that scheduler code be able to identify the current owner of a mutex. Expose __mutex_owner() for this purpose (alone!). Includes a null mutex check, so that users of the function can be simplified. Cc: Joel Fernandes Cc: Qais Yousef Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Juri Lelli Cc: Vincent Guittot Cc: Dietmar Eggemann Cc: Valentin Schneider Cc: Steven Rostedt Cc: Ben Segall Cc: Zimuzo Ezeozue Cc: Mel Gorman Cc: Will Deacon Cc: Waiman Long Cc: Boqun Feng Cc: "Paul E. McKenney" Cc: Metin Kaya Cc: Xuewen Yan Cc: K Prateek Nayak Cc: Thomas Gleixner Cc: Daniel Lezcano Cc: kernel-team@android.com Tested-by: K Prateek Nayak Tested-by: Metin Kaya Reviewed-by: Metin Kaya Reviewed-by: Valentin Schneider Signed-off-by: Juri Lelli [Removed the EXPORT_SYMBOL] Signed-off-by: Valentin Schneider Signed-off-by: Connor O'Brien [jstultz: Reworked per Peter's suggestions] Signed-off-by: John Stultz --- v4: * Move __mutex_owner() to kernel/locking/mutex.h instead of adding a new globally available accessor function to keep the exposure of this low, along with keeping it an inline function, as suggested by PeterZ v10: * Handle null lock ptr, to simplify later code, as suggested by Metin Kaya v11: * Tweak commit message suggested by Metin Kaya --- kernel/locking/mutex.c | 25 ------------------------- kernel/locking/mutex.h | 27 +++++++++++++++++++++++++++ 2 files changed, 27 insertions(+), 25 deletions(-) diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index cd248d1767eb..3302e52f0c96 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -56,31 +56,6 @@ __mutex_init(struct mutex *lock, const char *name, struc= t lock_class_key *key) } EXPORT_SYMBOL(__mutex_init); =20 -/* - * @owner: contains: 'struct task_struct *' to the current lock owner, - * NULL means not owned. Since task_struct pointers are aligned at - * at least L1_CACHE_BYTES, we have low bits to store extra state. - * - * Bit0 indicates a non-empty waiter list; unlock must issue a wakeup. - * Bit1 indicates unlock needs to hand the lock to the top-waiter - * Bit2 indicates handoff has been done and we're waiting for pickup. - */ -#define MUTEX_FLAG_WAITERS 0x01 -#define MUTEX_FLAG_HANDOFF 0x02 -#define MUTEX_FLAG_PICKUP 0x04 - -#define MUTEX_FLAGS 0x07 - -/* - * Internal helper function; C doesn't allow us to hide it :/ - * - * DO NOT USE (outside of mutex code). - */ -static inline struct task_struct *__mutex_owner(struct mutex *lock) -{ - return (struct task_struct *)(atomic_long_read(&lock->owner) & ~MUTEX_FLA= GS); -} - static inline struct task_struct *__owner_task(unsigned long owner) { return (struct task_struct *)(owner & ~MUTEX_FLAGS); diff --git a/kernel/locking/mutex.h b/kernel/locking/mutex.h index 0b2a79c4013b..cbff35b9b7ae 100644 --- a/kernel/locking/mutex.h +++ b/kernel/locking/mutex.h @@ -20,6 +20,33 @@ struct mutex_waiter { #endif }; =20 +/* + * @owner: contains: 'struct task_struct *' to the current lock owner, + * NULL means not owned. Since task_struct pointers are aligned at + * at least L1_CACHE_BYTES, we have low bits to store extra state. + * + * Bit0 indicates a non-empty waiter list; unlock must issue a wakeup. + * Bit1 indicates unlock needs to hand the lock to the top-waiter + * Bit2 indicates handoff has been done and we're waiting for pickup. + */ +#define MUTEX_FLAG_WAITERS 0x01 +#define MUTEX_FLAG_HANDOFF 0x02 +#define MUTEX_FLAG_PICKUP 0x04 + +#define MUTEX_FLAGS 0x07 + +/* + * Internal helper function; C doesn't allow us to hide it :/ + * + * DO NOT USE (outside of mutex & scheduler code). + */ +static inline struct task_struct *__mutex_owner(struct mutex *lock) +{ + if (!lock) + return NULL; + return (struct task_struct *)(atomic_long_read(&lock->owner) & ~MUTEX_FLA= GS); +} + #ifdef CONFIG_DEBUG_MUTEXES extern void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter); --=20 2.47.0.rc0.187.ge670bccf7e-goog