From nobody Fri Dec 19 07:28:11 2025 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (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 E9B011BBBF7 for ; Thu, 29 Aug 2024 22:52:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724971946; cv=none; b=SzNkXf3zRSRKNTjHbAo7xa5U+lt0KvSfBYyb5J8lBmgHYmDi3SdKuRoi/5bcN3Xk7oSBnuVO167oU1p3IdZFodwLBfmoUDTpC2p5xBZz/zE/yKxztbKRTgMU36Tvg85fK6Cws4odCb60UEJw3YJhuP70jteJVGsZoKQqvQbyshQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724971946; c=relaxed/simple; bh=3hB7bYjjH7sR1VJjuhchcYjwszE2LHNIrp2NDmBBo2g=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=OVdzUL/hebC9BUGfQhHP0vhG8mA7eOjmVbMGlChdWhTvxVsvxGw/6pVEbuJEChGHNKzztb88paY9if3RjxtvUPHmVuMNITbSxHeaI9CyxHO7N6B4G98oZTpntuaJrYSVPvy6h9PF+Dix03K7MVLMbpIxrXCuItfvXRh2+F9KbnI= 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=nIMAV3fH; arc=none smtp.client-ip=209.85.214.201 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="nIMAV3fH" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-201e94a71a0so11683895ad.1 for ; Thu, 29 Aug 2024 15:52:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1724971944; x=1725576744; 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=c6UuP9SE3/x3SmEG+F7YOUZFcdOqMrQ2TnJ/lc47nSs=; b=nIMAV3fH24GoeIJp15ASa+jonlZ69+Zg6vhNGAEDMSszYgdsI1vg74MXXtENRQWq6h a435DFRAfrsIVM/q4MlUJ9ZGNbKEKlre0uCxyuiahMCTEr9iY6a8Pyr2HlOSP9WReHyO H0OiAMic3WiSyFEjRhUOHYluo8jmc+9W/2xxiHMkBhQHGrBaMuGEVi+V42uJGFaqYRxy B6R43IkGrSq77X6orR0Cl+6gKQXrZ9ZBaQ7eOIodPHNO12Atpiz94CJuSFFHuOb15ZdY k7MPvGiaxHeVjWUXJFXwBfLxZhcOvwUfiJ9cp6OIoedAK0KrtbFpm9jguq4lKVAnPPAy k4cw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724971944; x=1725576744; 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=c6UuP9SE3/x3SmEG+F7YOUZFcdOqMrQ2TnJ/lc47nSs=; b=v984C9Vs2KRi1hTP9baDsK5DHC1fJ1lqqe0Z6Kx888xlN3+s0XERBqgQG1JIa4R1dQ nAQiXJKzZDcup/gll8xIquax1CpJT3oYk9kzpwnSgGKAC0cxhmL+APxRhK+AhGEd5JPH 7yymWhrkOzaz7ItvtGWqDyR/OMj6cPAdSEVGZzeeOCsQHtMoVqSfLA/9c2u24HkRC5by kQ0wprvI6FiwCElP46oZ2D+l/4t5+05eYmnci65AU+UaPz7oJm/74UF3/0jaQIJBg6/X ogB/qkc2OAt7J2sWc7ut3QiGWGJtHZh7s3D+rnDwBPjcdbkok9n8KrLGaxmYOn1dTNEt auWQ== X-Gm-Message-State: AOJu0YxQER4kAKT0iJHv/M5auVWbQPe0pilPFpOe5IwckzUCsLX/5F7b /yuxBXwQBlTXhmw8zzyuKrES2sX5BS4wxTRkrxiLrpd9YbfSGiMF1glSd2d2K2A9ZQso9OopFDg s0poMlP2EjQlzol3AZHPBDQlYcFkXA+3mxaAuRqge0pqj4SUCPzd10x2wFSk7Ov/V8nZA7Dl+Aa Yar0G5h0WuVYAWh6POQ+ZfVZ1E2a1xMAkxM03snSpHPycd X-Google-Smtp-Source: AGHT+IEHcmgh+c/05aLYwKgX0+8iCbrEbDXsMw0EF0IhhsAT1iox2QjpGxm4WeY9l69heP1xCgQzpIwfG3iz X-Received: from jstultz-noogler2.c.googlers.com ([fda3:e722:ac3:cc00:24:72f4:c0a8:600]) (user=jstultz job=sendgmr) by 2002:a17:903:4303:b0:1f9:e5e4:494b with SMTP id d9443c01a7336-2050e9aaf54mr92895ad.2.1724971942564; Thu, 29 Aug 2024 15:52:22 -0700 (PDT) Date: Thu, 29 Aug 2024 15:52:03 -0700 In-Reply-To: <20240829225212.6042-1-jstultz@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240829225212.6042-1-jstultz@google.com> X-Mailer: git-send-email 2.46.0.469.g59c65b2a67-goog Message-ID: <20240829225212.6042-4-jstultz@google.com> Subject: [RESEND][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 cd248d1767eb3..3302e52f0c967 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 0b2a79c4013bd..cbff35b9b7ae3 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 2.46.0.469.g59c65b2a67-goog