From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-171.mta0.migadu.com (out-171.mta0.migadu.com [91.218.175.171]) (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 464933FE7 for ; Tue, 24 Jun 2025 01:35:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750728945; cv=none; b=XP6dNl4EIfBpCZOwPPR6+jl8o9m1VJPFVK1S8N0tSlWz6W1ca+M/hvp1uXXWJw8mOqlXg3ihFr2iq2wgUXmrDjgwoQWbiNLKRsqJA1I+pcva8kLVLQfdzAKB4AyghyU0eNItlEUUZpX+4JyhUkUPArlfcgmgE8QUEEbVs+ilS9E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750728945; c=relaxed/simple; bh=0R8kh9vmNHmJxUvVtlnuaKUoGaU/jMFPFGc8nGNfCcU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=twf5exnwKG0GnX0zC5Ps4coszUa5ikgDFBENP771aESnmJ4w8GOn4SLDY8eTTfycU9Drwq7XNWntd+KL+TIQ1qfG8NpnK5BQSkp+abyDcWpwdviT0U2u4jVf/xMJOuS2ya84lrARQL9472jPR0wIx5miyRSVCKdx+97FMOtD8EU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=ih0WBsa6; arc=none smtp.client-ip=91.218.175.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="ih0WBsa6" Message-ID: <6a1d2610-2407-4449-a3ff-2fbfa85f96ae@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1750728939; h=from:from: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=IKlAz9lF4G5Swjm3N/6rrWAQte/82d71dVG7rJqEujs=; b=ih0WBsa65QZfw9GxfDwUtwhUb8YuA+K4PhUXvEGaFDSm/sbjl7NCLJNuH2XJQ2ZojIzqHg EyrK/sElvtEKOldXNm7aUe9E0jWoVu2APBDe5gyUHb79lYhr3iq4o6UshNhwlstIJShlOn 6EY2NOH/+CYkcWnmJaVfiIgS70ap+8w= Date: Tue, 24 Jun 2025 09:35:15 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH RFC 1/3] locking/rwsem: make owner helpers globally available To: "Masami Hiramatsu (Google)" Cc: akpm@linux-foundation.org, zi.li@linux.dev, anna.schumaker@oracle.com, boqun.feng@gmail.com, joel.granados@kernel.org, jstultz@google.com, kent.overstreet@linux.dev, leonylgao@tencent.com, linux-kernel@vger.kernel.org, longman@redhat.com, mingo@redhat.com, mingzhe.yang@ly.com, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, tfiga@chromium.org, will@kernel.org, Lance Yang References: <20250612042005.99602-1-lance.yang@linux.dev> <20250612042005.99602-2-lance.yang@linux.dev> <20250624091731.f4d3cf296943ce45e97a631f@kernel.org> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Lance Yang In-Reply-To: <20250624091731.f4d3cf296943ce45e97a631f@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 2025/6/24 08:17, Masami Hiramatsu (Google) wrote: > On Thu, 12 Jun 2025 12:19:24 +0800 > Lance Yang wrote: > >> From: Lance Yang >> >> In preparation for extending blocker tracking to support rwsems, make the >> rwsem_owner() and is_rwsem_reader_owned() helpers globally available for >> determining if the blocker is a writer or one of the readers. >> > > Looks good to me. > > Reviewed-by: Masami Hiramatsu (Google) > > Thanks! Thanks for taking the time to review! Lance > >> Signed-off-by: Lance Yang >> --- >> include/linux/rwsem.h | 12 ++++++++++++ >> kernel/locking/rwsem.c | 8 +++++--- >> 2 files changed, 17 insertions(+), 3 deletions(-) >> >> diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h >> index c8b543d428b0..544853bed5b9 100644 >> --- a/include/linux/rwsem.h >> +++ b/include/linux/rwsem.h >> @@ -132,6 +132,18 @@ static inline int rwsem_is_contended(struct rw_semaphore *sem) >> return !list_empty(&sem->wait_list); >> } >> >> +#if defined(CONFIG_DEBUG_RWSEMS) || defined(CONFIG_DETECT_HUNG_TASK_BLOCKER) >> +/* >> + * Return just the real task structure pointer of the owner >> + */ >> +extern struct task_struct *rwsem_owner(struct rw_semaphore *sem); >> + >> +/* >> + * Return true if the rwsem is owned by a reader. >> + */ >> +extern bool is_rwsem_reader_owned(struct rw_semaphore *sem); >> +#endif >> + >> #else /* !CONFIG_PREEMPT_RT */ >> >> #include >> diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c >> index 2ddb827e3bea..6cb29442d4fc 100644 >> --- a/kernel/locking/rwsem.c >> +++ b/kernel/locking/rwsem.c >> @@ -181,11 +181,11 @@ static inline void rwsem_set_reader_owned(struct rw_semaphore *sem) >> __rwsem_set_reader_owned(sem, current); >> } >> >> -#ifdef CONFIG_DEBUG_RWSEMS >> +#if defined(CONFIG_DEBUG_RWSEMS) || defined(CONFIG_DETECT_HUNG_TASK_BLOCKER) >> /* >> * Return just the real task structure pointer of the owner >> */ >> -static inline struct task_struct *rwsem_owner(struct rw_semaphore *sem) >> +struct task_struct *rwsem_owner(struct rw_semaphore *sem) >> { >> return (struct task_struct *) >> (atomic_long_read(&sem->owner) & ~RWSEM_OWNER_FLAGS_MASK); >> @@ -194,7 +194,7 @@ static inline struct task_struct *rwsem_owner(struct rw_semaphore *sem) >> /* >> * Return true if the rwsem is owned by a reader. >> */ >> -static inline bool is_rwsem_reader_owned(struct rw_semaphore *sem) >> +bool is_rwsem_reader_owned(struct rw_semaphore *sem) >> { >> /* >> * Check the count to see if it is write-locked. >> @@ -205,7 +205,9 @@ static inline bool is_rwsem_reader_owned(struct rw_semaphore *sem) >> return false; >> return rwsem_test_oflags(sem, RWSEM_READER_OWNED); >> } >> +#endif >> >> +#ifdef CONFIG_DEBUG_RWSEMS >> /* >> * With CONFIG_DEBUG_RWSEMS configured, it will make sure that if there >> * is a task pointer in owner of a reader-owned rwsem, it will be the >> -- >> 2.49.0 >> > >