From nobody Mon Feb 9 18:44:49 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org ARC-Seal: i=1; a=rsa-sha256; t=1585214410; cv=none; d=zohomail.com; s=zohoarc; b=Ne4xqIPBKsxURA9RPxQPArI2HDoY4Os3Xh6mxiyNcBykcbS1QjGwTz2leM7UOMXUHwCr1E8NJNG4vY0ZfbO47TGeVPZr80OQ4ycQQCdZqTzZ3NCVM4sHz5IpdJLBZjca4ohkvFOJwxaGHmxA+DiS6x8aZJH3cRiwrLaKvvriKqw= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1585214410; h=Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Help:List-Unsubscribe:Message-ID:References:Sender:Subject:To; bh=8v6fD/90KOMfX8JqpQNtG/mfgyQBDGGDzeKoP4pdh98=; b=NphwJv7I3h71+S96psT7EfbqWj1Y3ER8moVGgQ2xOz6q/VJxLSmIupOTGxPCskO/GM30f6+w4P9ByGrKvNR895hC6Ru//AUpF1kQDBu5w/8uHhK0rrkZUNSZy2ai4j1Ss1uHwvD0qxDI28UTCRBXWdWIedJfQh/UINLV418ffpA= ARC-Authentication-Results: i=1; mx.zohomail.com; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Return-Path: Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) by mx.zohomail.com with SMTPS id 1585214410152126.03197588527485; Thu, 26 Mar 2020 02:20:10 -0700 (PDT) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1jHOft-0005g9-Po; Thu, 26 Mar 2020 09:19:41 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1jHOfs-0005f7-2k for xen-devel@lists.xenproject.org; Thu, 26 Mar 2020 09:19:40 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id e1ddaf36-6f42-11ea-877f-12813bfff9fa; Thu, 26 Mar 2020 09:19:25 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 98299AF3D; Thu, 26 Mar 2020 09:19:23 +0000 (UTC) X-Inumbo-ID: e1ddaf36-6f42-11ea-877f-12813bfff9fa X-Virus-Scanned: by amavisd-new at test-mx.suse.de From: Juergen Gross To: xen-devel@lists.xenproject.org Date: Thu, 26 Mar 2020 10:19:18 +0100 Message-Id: <20200326091918.12388-6-jgross@suse.com> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20200326091918.12388-1-jgross@suse.com> References: <20200326091918.12388-1-jgross@suse.com> Subject: [Xen-devel] [PATCH v8 5/5] xen/rcu: add per-lock counter in debug builds X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Juergen Gross , Stefano Stabellini , Julien Grall , Wei Liu , Andrew Cooper , Ian Jackson , George Dunlap , Jan Beulich Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Add a lock specific counter to rcu read locks in debug builds. This allows to test for matching lock/unlock calls. This will help to avoid cases like the one fixed by commit 98ed1f43cc2c89 where different rcu read locks were referenced in the lock and unlock calls. Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich --- V5: - updated commit message (Jan Beulich) --- xen/include/xen/rcupdate.h | 46 +++++++++++++++++++++++++++++++++---------= ---- 1 file changed, 33 insertions(+), 13 deletions(-) diff --git a/xen/include/xen/rcupdate.h b/xen/include/xen/rcupdate.h index 6f2587058e..cda1be9c88 100644 --- a/xen/include/xen/rcupdate.h +++ b/xen/include/xen/rcupdate.h @@ -37,21 +37,50 @@ #include #include #include +#include =20 #define __rcu =20 +#ifndef NDEBUG +/* * Lock type for passing to rcu_read_{lock,unlock}. */ +struct _rcu_read_lock { + atomic_t cnt; +}; +typedef struct _rcu_read_lock rcu_read_lock_t; +#define DEFINE_RCU_READ_LOCK(x) rcu_read_lock_t x =3D { .cnt =3D ATOMIC_IN= IT(0) } +#define RCU_READ_LOCK_INIT(x) atomic_set(&(x)->cnt, 0) + +#else +/* + * Dummy lock type for passing to rcu_read_{lock,unlock}. Currently exists + * only to document the reason for rcu_read_lock() critical sections. + */ +struct _rcu_read_lock {}; +typedef struct _rcu_read_lock rcu_read_lock_t; +#define DEFINE_RCU_READ_LOCK(x) rcu_read_lock_t x +#define RCU_READ_LOCK_INIT(x) + +#endif + DECLARE_PER_CPU(unsigned int, rcu_lock_cnt); =20 -static inline void rcu_quiesce_disable(void) +static inline void rcu_quiesce_disable(rcu_read_lock_t *lock) { preempt_disable(); this_cpu(rcu_lock_cnt)++; +#ifndef NDEBUG + atomic_inc(&lock->cnt); +#endif barrier(); } =20 -static inline void rcu_quiesce_enable(void) +static inline void rcu_quiesce_enable(rcu_read_lock_t *lock) { barrier(); +#ifndef NDEBUG + ASSERT(atomic_read(&lock->cnt)); + atomic_dec(&lock->cnt); +#endif this_cpu(rcu_lock_cnt)--; preempt_enable(); } @@ -81,15 +110,6 @@ struct rcu_head { int rcu_pending(int cpu); int rcu_needs_cpu(int cpu); =20 -/* - * Dummy lock type for passing to rcu_read_{lock,unlock}. Currently exists - * only to document the reason for rcu_read_lock() critical sections. - */ -struct _rcu_read_lock {}; -typedef struct _rcu_read_lock rcu_read_lock_t; -#define DEFINE_RCU_READ_LOCK(x) rcu_read_lock_t x -#define RCU_READ_LOCK_INIT(x) - /** * rcu_read_lock - mark the beginning of an RCU read-side critical section. * @@ -119,7 +139,7 @@ typedef struct _rcu_read_lock rcu_read_lock_t; */ static inline void rcu_read_lock(rcu_read_lock_t *lock) { - rcu_quiesce_disable(); + rcu_quiesce_disable(lock); } =20 /** @@ -130,7 +150,7 @@ static inline void rcu_read_lock(rcu_read_lock_t *lock) static inline void rcu_read_unlock(rcu_read_lock_t *lock) { ASSERT(!rcu_quiesce_allowed()); - rcu_quiesce_enable(); + rcu_quiesce_enable(lock); } =20 /* --=20 2.16.4