From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 840AEECAAD5 for ; Mon, 29 Aug 2022 12:54:32 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4MGVkv0Jpvz3f66 for ; Mon, 29 Aug 2022 22:54:31 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20210112 header.b=DUROuHk1; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=flex--elver.bounces.google.com (client-ip=2a00:1450:4864:20::649; helo=mail-ej1-x649.google.com; envelope-from=3mbumywukdfy29j2f4cc492.0ca96bildd0-12j96ghg.cn9yzg.cf4@flex--elver.bounces.google.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20210112 header.b=DUROuHk1; dkim-atps=neutral Received: from mail-ej1-x649.google.com (mail-ej1-x649.google.com [IPv6:2a00:1450:4864:20::649]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4MGVbw5WHnz3c7s for ; Mon, 29 Aug 2022 22:48:28 +1000 (AEST) Received: by mail-ej1-x649.google.com with SMTP id xh12-20020a170906da8c00b007413144e87fso2156406ejb.14 for ; Mon, 29 Aug 2022 05:48:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc; bh=o7nFvD+bAzzd8hTxdy6J5SFI8QAvwQGuiGUQWboy0hk=; b=DUROuHk1Z9qzwl+b2DTEg2S7HJMexhpmqANb/PJZ7O33R9XhSPct7AwehP14PQc/2o wK/bi8a2CwUsCNYLZ60BVrbEBT9p31oxiK+AfnIEOciyJytERkocF14TQxcpALfKW3+m b2Ub+eMgVCVEVNppFz86zBqIyKvR0lUxlYrSs0Pqqu53c88/O9WnN5AbglZY4E2lNY3X UurK/UKzohtpKpt81PvQ4NXYcynS9qosWESRGDtGbt4p3CdpxU/ZwTvmCC71hiCrb5Iz oBnMf/JVbgAxkVDKJuMfwanruY91nDmZy+mUGQ78tN/tN+0RJuWqqSZWWdmcn4+YhWS4 IZ8g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc; bh=o7nFvD+bAzzd8hTxdy6J5SFI8QAvwQGuiGUQWboy0hk=; b=zVETu/z3azNI3FfuEWkWI0CmP9fDPQmSHV3mjo/d8G768uP0lCrxMbp5FnQDARkfa7 n5Cf7NTK0Kegyv2ge/QmDR2FCTAReE2jhvxePaw876GJ2SR83im6eJQB/fp6EOrc2yJs rEKu/xgKJdoEfKMSd21mtUFpCZ4ruQzPPhd0ndTP1gS8QIWLvVXILyQx1TJ2S6waVICo WvZGM2W7rmCymmGxzIy8HRONylKr9rygL1Sz9sBaLc9HO7ipZ9FtHZoiuV/GLHY7Ey18 rDjjhXJ9RNgjv8Jy62trXjjP+zdsTK5rTKBp+sRsagNO+GG4o9pnuEt+fcA2VZAPd+CU AlvA== X-Gm-Message-State: ACgBeo1qnChGDAS42J3YH5dedDj/Ix9jqh/wAXjdEy1k0oqxsbQJuDQc uwrQK8xYk9skp4jl2jErFDv6e9E3yw== X-Google-Smtp-Source: AA6agR5wokwGhbG/dPuolBfo3Bpkl9cRXVj3x5ekleyIMoAvz+i6ptf2ezpCAANeuPi0p5VgMRtvOQZZzA== X-Received: from elver.muc.corp.google.com ([2a00:79e0:9c:201:196d:4fc7:fa9c:62e3]) (user=elver job=sendgmr) by 2002:a17:907:75c6:b0:741:75a0:b82b with SMTP id jl6-20020a17090775c600b0074175a0b82bmr4672915ejc.465.1661777305817; Mon, 29 Aug 2022 05:48:25 -0700 (PDT) Date: Mon, 29 Aug 2022 14:47:15 +0200 In-Reply-To: <20220829124719.675715-1-elver@google.com> Mime-Version: 1.0 References: <20220829124719.675715-1-elver@google.com> X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Message-ID: <20220829124719.675715-11-elver@google.com> Subject: [PATCH v4 10/14] locking/percpu-rwsem: Add percpu_is_write_locked() and percpu_is_read_locked() From: Marco Elver To: elver@google.com, Peter Zijlstra , Frederic Weisbecker , Ingo Molnar Content-Type: text/plain; charset="UTF-8" X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Ian Rogers , linux-sh@vger.kernel.org, Alexander Shishkin , x86@kernel.org, linuxppc-dev@lists.ozlabs.org, Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, kasan-dev@googlegroups.com, Namhyung Kim , Thomas Gleixner , Jiri Olsa , Dmitry Vyukov Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Implement simple accessors to probe percpu-rwsem's locked state: percpu_is_write_locked(), percpu_is_read_locked(). Signed-off-by: Marco Elver Reviewed-by: Dmitry Vyukov Acked-by: Ian Rogers --- v4: * Due to spurious read_count increments in __percpu_down_read_trylock() if sem->block != 0, check that !sem->block (reported by Peter). v2: * New patch. --- include/linux/percpu-rwsem.h | 6 ++++++ kernel/locking/percpu-rwsem.c | 6 ++++++ 2 files changed, 12 insertions(+) diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h index 5fda40f97fe9..36b942b67b7d 100644 --- a/include/linux/percpu-rwsem.h +++ b/include/linux/percpu-rwsem.h @@ -121,9 +121,15 @@ static inline void percpu_up_read(struct percpu_rw_semaphore *sem) preempt_enable(); } +extern bool percpu_is_read_locked(struct percpu_rw_semaphore *); extern void percpu_down_write(struct percpu_rw_semaphore *); extern void percpu_up_write(struct percpu_rw_semaphore *); +static inline bool percpu_is_write_locked(struct percpu_rw_semaphore *sem) +{ + return atomic_read(&sem->block); +} + extern int __percpu_init_rwsem(struct percpu_rw_semaphore *, const char *, struct lock_class_key *); diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c index 5fe4c5495ba3..185bd1c906b0 100644 --- a/kernel/locking/percpu-rwsem.c +++ b/kernel/locking/percpu-rwsem.c @@ -192,6 +192,12 @@ EXPORT_SYMBOL_GPL(__percpu_down_read); __sum; \ }) +bool percpu_is_read_locked(struct percpu_rw_semaphore *sem) +{ + return per_cpu_sum(*sem->read_count) != 0 && !atomic_read(&sem->block); +} +EXPORT_SYMBOL_GPL(percpu_is_read_locked); + /* * Return true if the modular sum of the sem->read_count per-CPU variable is * zero. If this sum is zero, then it is stable due to the fact that if any -- 2.37.2.672.g94769d06f0-goog