From patchwork Mon Nov 28 12:20:05 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Nicolai_H=C3=A4hnle?= X-Patchwork-Id: 9449475 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 9C72F600CB for ; Mon, 28 Nov 2016 12:20:55 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8C6E620453 for ; Mon, 28 Nov 2016 12:20:55 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8122A27BFF; Mon, 28 Nov 2016 12:20:55 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_MED, T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 0C59520453 for ; Mon, 28 Nov 2016 12:20:55 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 40B776E2D2; Mon, 28 Nov 2016 12:20:37 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from mail-wj0-x243.google.com (mail-wj0-x243.google.com [IPv6:2a00:1450:400c:c01::243]) by gabe.freedesktop.org (Postfix) with ESMTPS id 105E16E2BD for ; Mon, 28 Nov 2016 12:20:27 +0000 (UTC) Received: by mail-wj0-x243.google.com with SMTP id kp2so13843555wjc.0 for ; Mon, 28 Nov 2016 04:20:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=PiF7crrq6Atwd1gupifWWfiHEyfXHK9NqMGcdDQSlDc=; b=jf13F2IsRE3fivDmt/STBCFac7Nboe4pBzPJjD/0wbNncPv+osmiutzIlOXfKl8bDX Xk+klXMMC2ZFzpdDiBnZimChdduXxeW7ixF4Lqi9WCfN/FU5d2K7sp6HFEjcKnN8Xm9k /uKO5GqwxrMWqszEGTR+VbF4ovXiqJO/5XIqPF1rtPTLdN+1TSLZ/YG/F2iflzKjqXxe RwYBBqrjbtbOQmJ7GF1PpjpFhni+uOmjxa9CHSJngEzfzj88mBPECIyUVf/zcTVGwE5c syMyOQosrJcZYHjvonAqk8jF37eSTY3yEFgouhwuUCqcaqvL/Yx6pb+L3TqBC/dr12he ++Yw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=PiF7crrq6Atwd1gupifWWfiHEyfXHK9NqMGcdDQSlDc=; b=UhWkY6ZaUDI5/cqfepFjs6SisJ0JswnrmtLHT39JToye2LSJva73zKdfRLIKz44MJU RyN69mg4GO6s8YdCwj9tTE2stpytJNjWBLzWPQSYQrGX0ehSnsJH1gv0oDyYMpUiEDEw 5i5Bbb+B1NfEWHtIPtyzS8yuc+LPqcZQUICf5Erx18leCaPe2eM3SsBvUwXWdAwULFVO qAwxxyWmc9alUSZPUyyqbw7QemN088Dl75442/can9IVrsmF1qHVftMkIQiZ/ZaKhhMs UEOPQdp38Qti16RfIWW0Pm08FdTZBvCQO0V90rpA3bHb6P+qUhOxQvW5NH3TtG50kecC iztg== X-Gm-Message-State: AKaTC02gGJkgF723HCdmvolRKMg6ysoYxl4LH96ZCWfQLhrcVHTMg7PerXviz+wjHMFk4A== X-Received: by 10.194.58.198 with SMTP id t6mr17823233wjq.44.1480335625343; Mon, 28 Nov 2016 04:20:25 -0800 (PST) Received: from cassiopeia.fritz.box ([2001:a61:1119:dc01:d88b:9432:f601:27ed]) by smtp.gmail.com with ESMTPSA id a13sm28830511wma.18.2016.11.28.04.20.24 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 28 Nov 2016 04:20:24 -0800 (PST) From: =?UTF-8?q?Nicolai=20H=C3=A4hnle?= To: linux-kernel@vger.kernel.org Subject: [PATCH 04/11] locking/ww_mutex: Set use_ww_ctx even when locking without a context Date: Mon, 28 Nov 2016 13:20:05 +0100 Message-Id: <1480335612-12069-5-git-send-email-nhaehnle@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1480335612-12069-1-git-send-email-nhaehnle@gmail.com> References: <1480335612-12069-1-git-send-email-nhaehnle@gmail.com> MIME-Version: 1.0 Cc: Maarten Lankhorst , =?UTF-8?q?Nicolai=20H=C3=A4hnle?= , Peter Zijlstra , dri-devel@lists.freedesktop.org, Ingo Molnar X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: Nicolai Hähnle We will add a new field to struct mutex_waiter. This field must be initialized for all waiters if any waiter uses the ww_use_ctx path. So there is a trade-off: Keep ww_mutex locking without a context on the faster non-use_ww_ctx path, at the cost of adding the initialization to all mutex locks (including non-ww_mutexes), or avoid the additional cost for non-ww_mutex locks, at the cost of adding additional checks to the use_ww_ctx path. We take the latter choice. It may be worth eliminating the users of ww_mutex_lock(lock, NULL), but there are a lot of them. Move the declaration of ww in __mutex_lock_common closer to its uses because gcc otherwise (incorrectly) believes ww may be used without initialization. Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Maarten Lankhorst Cc: Daniel Vetter Cc: Chris Wilson Cc: dri-devel@lists.freedesktop.org Signed-off-by: Nicolai Hähnle --- include/linux/ww_mutex.h | 11 ++--------- kernel/locking/mutex.c | 37 +++++++++++++++++++++++++------------ 2 files changed, 27 insertions(+), 21 deletions(-) diff --git a/include/linux/ww_mutex.h b/include/linux/ww_mutex.h index 2bb5deb..a5960e5 100644 --- a/include/linux/ww_mutex.h +++ b/include/linux/ww_mutex.h @@ -222,11 +222,7 @@ extern int __must_check __ww_mutex_lock_interruptible(struct ww_mutex *lock, */ static inline int ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) { - if (ctx) - return __ww_mutex_lock(lock, ctx); - - mutex_lock(&lock->base); - return 0; + return __ww_mutex_lock(lock, ctx); } /** @@ -262,10 +258,7 @@ static inline int ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ct static inline int __must_check ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) { - if (ctx) - return __ww_mutex_lock_interruptible(lock, ctx); - else - return mutex_lock_interruptible(&lock->base); + return __ww_mutex_lock_interruptible(lock, ctx); } /** diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index 200629a..585627f 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -381,7 +381,7 @@ bool mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner, break; } - if (use_ww_ctx && ww_ctx->acquired > 0) { + if (use_ww_ctx && ww_ctx && ww_ctx->acquired > 0) { struct ww_mutex *ww; ww = container_of(lock, struct ww_mutex, base); @@ -640,10 +640,11 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, struct mutex_waiter waiter; unsigned long flags; bool first = false; - struct ww_mutex *ww; int ret; - if (use_ww_ctx) { + if (use_ww_ctx && ww_ctx) { + struct ww_mutex *ww; + ww = container_of(lock, struct ww_mutex, base); if (unlikely(ww_ctx == READ_ONCE(ww->ctx))) return -EALREADY; @@ -656,8 +657,12 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx, false)) { /* got the lock, yay! */ lock_acquired(&lock->dep_map, ip); - if (use_ww_ctx) + if (use_ww_ctx && ww_ctx) { + struct ww_mutex *ww; + + ww = container_of(lock, struct ww_mutex, base); ww_mutex_set_context_fastpath(ww, ww_ctx); + } preempt_enable(); return 0; } @@ -702,7 +707,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, goto err; } - if (use_ww_ctx && ww_ctx->acquired > 0) { + if (use_ww_ctx && ww_ctx && ww_ctx->acquired > 0) { ret = __ww_mutex_lock_check_stamp(lock, ww_ctx); if (ret) goto err; @@ -742,8 +747,12 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, /* got the lock - cleanup and rejoice! */ lock_acquired(&lock->dep_map, ip); - if (use_ww_ctx) + if (use_ww_ctx && ww_ctx) { + struct ww_mutex *ww; + + ww = container_of(lock, struct ww_mutex, base); ww_mutex_set_context_slowpath(ww, ww_ctx); + } spin_unlock_mutex(&lock->wait_lock, flags); preempt_enable(); @@ -830,8 +839,9 @@ __ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) might_sleep(); ret = __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE, - 0, &ctx->dep_map, _RET_IP_, ctx, 1); - if (!ret && ctx->acquired > 1) + 0, ctx ? &ctx->dep_map : NULL, _RET_IP_, + ctx, 1); + if (!ret && ctx && ctx->acquired > 1) return ww_mutex_deadlock_injection(lock, ctx); return ret; @@ -845,9 +855,10 @@ __ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) might_sleep(); ret = __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE, - 0, &ctx->dep_map, _RET_IP_, ctx, 1); + 0, ctx ? &ctx->dep_map : NULL, _RET_IP_, + ctx, 1); - if (!ret && ctx->acquired > 1) + if (!ret && ctx && ctx->acquired > 1) return ww_mutex_deadlock_injection(lock, ctx); return ret; @@ -1034,7 +1045,8 @@ __ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) might_sleep(); if (__mutex_trylock_fast(&lock->base)) { - ww_mutex_set_context_fastpath(lock, ctx); + if (ctx) + ww_mutex_set_context_fastpath(lock, ctx); return 0; } @@ -1048,7 +1060,8 @@ __ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) might_sleep(); if (__mutex_trylock_fast(&lock->base)) { - ww_mutex_set_context_fastpath(lock, ctx); + if (ctx) + ww_mutex_set_context_fastpath(lock, ctx); return 0; }