From patchwork Thu Jun 30 13:59:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Aring X-Patchwork-Id: 12901885 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12A1BC43334 for ; Thu, 30 Jun 2022 14:14:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236985AbiF3OOb (ORCPT ); Thu, 30 Jun 2022 10:14:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43906 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237080AbiF3ON6 (ORCPT ); Thu, 30 Jun 2022 10:13:58 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 0CE39419A0 for ; Thu, 30 Jun 2022 06:59:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1656597588; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YL9f1II4Mw4H7t2E0klzVA5qKcGu0RnSH4xCbZTGJWU=; b=YO4eepO7KrJ/BGFOU2/A+wBBSCB1EEaK8dzrgMKdC4U0kF9PuFYBxU/CWZsk7JKmMSNx8h bR81l/E2gBJ3VePUWRoyTnbCYfMifp9vbR9mFD5xg3afvcYn6ktp/NvhmkVxlwX5rKsXcM 3fQ1B9N284H6tfWAs4rUy8N7HeHLAzo= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-22--w1_ynfMMyqKXXq4Nnz9sA-1; Thu, 30 Jun 2022 09:59:45 -0400 X-MC-Unique: -w1_ynfMMyqKXXq4Nnz9sA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E44E31C004ED; Thu, 30 Jun 2022 13:59:44 +0000 (UTC) Received: from fs-i40c-03.fs.lab.eng.bos.redhat.com (fs-i40c-03.fs.lab.eng.bos.redhat.com [10.16.224.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9166A815B; Thu, 30 Jun 2022 13:59:44 +0000 (UTC) From: Alexander Aring To: will@kernel.org Cc: peterz@infradead.org, boqun.feng@gmail.com, mark.rutland@arm.com, thunder.leizhen@huawei.com, jacob.e.keller@intel.com, akpm@linux-foundation.org, linux-sparse@vger.kernel.org, cluster-devel@redhat.com, luc.vanoostenryck@gmail.com, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, aahringo@redhat.com Subject: [RFC 1/2] refcount: add __cond_lock() for conditional lock refcount API Date: Thu, 30 Jun 2022 09:59:33 -0400 Message-Id: <20220630135934.1799248-2-aahringo@redhat.com> In-Reply-To: <20220630135934.1799248-1-aahringo@redhat.com> References: <20220630135934.1799248-1-aahringo@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: linux-sparse@vger.kernel.org This patch adds the __cond_lock() macro to refcounts conditional lock API. Currently sparse cannot detect the conditional lock handling of refcount_dec_and_lock() functionality and prints a context imbalance warning like: warning: context imbalance in 'put_rsb' - unexpected unlock with this patch and having the refcount_dec_and_lock() functionality inside the if condition to decide whenever doing unlock or not the warning disappears. The patch follows a similar naming scheme like raw_spin_trylock() by adding a "raw_" prefix to refcount_dec_and_lock() functionality and introduce a macro for the replaced functions that uses __cond_lock() to signal that an acquire depends on the return value of the passed function. A cast to bool seems to be necessary because __cond_lock() does return a non-boolean scalar type. The __must_check annotation was tested and is still working with this patch applied. Signed-off-by: Alexander Aring --- include/linux/refcount.h | 21 ++++++++++++++++----- lib/refcount.c | 23 ++++++++++++----------- 2 files changed, 28 insertions(+), 16 deletions(-) diff --git a/include/linux/refcount.h b/include/linux/refcount.h index b8a6e387f8f9..be7b970ce475 100644 --- a/include/linux/refcount.h +++ b/include/linux/refcount.h @@ -361,9 +361,20 @@ static inline void refcount_dec(refcount_t *r) extern __must_check bool refcount_dec_if_one(refcount_t *r); extern __must_check bool refcount_dec_not_one(refcount_t *r); -extern __must_check bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock); -extern __must_check bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock); -extern __must_check bool refcount_dec_and_lock_irqsave(refcount_t *r, - spinlock_t *lock, - unsigned long *flags); +extern __must_check bool raw_refcount_dec_and_mutex_lock(refcount_t *r, + struct mutex *lock); +#define refcount_dec_and_mutex_lock(r, lock) \ + ((bool)(__cond_lock(lock, raw_refcount_dec_and_mutex_lock(r, lock)))) + +extern __must_check bool raw_refcount_dec_and_lock(refcount_t *r, + spinlock_t *lock); +#define refcount_dec_and_lock(r, lock) \ + ((bool)(__cond_lock(lock, raw_refcount_dec_and_lock(r, lock)))) + +extern __must_check bool raw_refcount_dec_and_lock_irqsave(refcount_t *r, + spinlock_t *lock, + unsigned long *flags); +#define refcount_dec_and_lock_irqsave(r, lock, flags) \ + ((bool)(__cond_lock(lock, raw_refcount_dec_and_lock_irqsave(r, lock, flags)))) + #endif /* _LINUX_REFCOUNT_H */ diff --git a/lib/refcount.c b/lib/refcount.c index a207a8f22b3c..1a8c7b9aba23 100644 --- a/lib/refcount.c +++ b/lib/refcount.c @@ -110,7 +110,7 @@ EXPORT_SYMBOL(refcount_dec_not_one); * Return: true and hold mutex if able to decrement refcount to 0, false * otherwise */ -bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock) +bool raw_refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock) { if (refcount_dec_not_one(r)) return false; @@ -123,11 +123,11 @@ bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock) return true; } -EXPORT_SYMBOL(refcount_dec_and_mutex_lock); +EXPORT_SYMBOL(raw_refcount_dec_and_mutex_lock); /** - * refcount_dec_and_lock - return holding spinlock if able to decrement - * refcount to 0 + * raw_refcount_dec_and_lock - return holding spinlock if able to decrement + * refcount to 0 * @r: the refcount * @lock: the spinlock to be locked * @@ -141,7 +141,7 @@ EXPORT_SYMBOL(refcount_dec_and_mutex_lock); * Return: true and hold spinlock if able to decrement refcount to 0, false * otherwise */ -bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock) +bool raw_refcount_dec_and_lock(refcount_t *r, spinlock_t *lock) { if (refcount_dec_not_one(r)) return false; @@ -154,11 +154,12 @@ bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock) return true; } -EXPORT_SYMBOL(refcount_dec_and_lock); +EXPORT_SYMBOL(raw_refcount_dec_and_lock); /** - * refcount_dec_and_lock_irqsave - return holding spinlock with disabled - * interrupts if able to decrement refcount to 0 + * raw_refcount_dec_and_lock_irqsave - return holding spinlock with disabled + * interrupts if able to decrement + * refcount to 0 * @r: the refcount * @lock: the spinlock to be locked * @flags: saved IRQ-flags if the is acquired @@ -169,8 +170,8 @@ EXPORT_SYMBOL(refcount_dec_and_lock); * Return: true and hold spinlock if able to decrement refcount to 0, false * otherwise */ -bool refcount_dec_and_lock_irqsave(refcount_t *r, spinlock_t *lock, - unsigned long *flags) +bool raw_refcount_dec_and_lock_irqsave(refcount_t *r, spinlock_t *lock, + unsigned long *flags) { if (refcount_dec_not_one(r)) return false; @@ -183,4 +184,4 @@ bool refcount_dec_and_lock_irqsave(refcount_t *r, spinlock_t *lock, return true; } -EXPORT_SYMBOL(refcount_dec_and_lock_irqsave); +EXPORT_SYMBOL(raw_refcount_dec_and_lock_irqsave);