From patchwork Mon Sep 9 14:31:30 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?b?SsO8cmdlbiBHcm/Dnw==?= X-Patchwork-Id: 11138121 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2BFC714DB for ; Mon, 9 Sep 2019 14:33:04 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 11B36206A1 for ; Mon, 9 Sep 2019 14:33:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 11B36206A1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1i7Khq-0001Sv-Gu; Mon, 09 Sep 2019 14:31:50 +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 1i7Kho-0001Rt-TN for xen-devel@lists.xenproject.org; Mon, 09 Sep 2019 14:31:48 +0000 X-Inumbo-ID: 8804fb50-d30e-11e9-ac0d-12813bfff9fa Received: from mx1.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 8804fb50-d30e-11e9-ac0d-12813bfff9fa; Mon, 09 Sep 2019 14:31:38 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 47B9BB668; Mon, 9 Sep 2019 14:31:37 +0000 (UTC) From: Juergen Gross To: xen-devel@lists.xenproject.org Date: Mon, 9 Sep 2019 16:31:30 +0200 Message-Id: <20190909143134.15379-2-jgross@suse.com> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20190909143134.15379-1-jgross@suse.com> References: <20190909143134.15379-1-jgross@suse.com> Subject: [Xen-devel] [PATCH v4 1/5] xen/spinlocks: in debug builds store cpu holding the lock 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 , Wei Liu , Konrad Rzeszutek Wilk , George Dunlap , Andrew Cooper , Ian Jackson , Tim Deegan , Julien Grall , Jan Beulich MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" Add the cpu currently holding the lock to struct lock_debug. This makes analysis of locking errors easier and it can be tested whether the correct cpu is releasing a lock again. Signed-off-by: Juergen Gross --- V2: - adjust types (Jan Beulich) V4: - add define for bitfield size to store cpu number (Jan Beulich) - make padding field unnamed (Jan Beulich) --- xen/common/spinlock.c | 33 ++++++++++++++++++++++++++------- xen/include/xen/spinlock.h | 28 +++++++++++++++++++--------- 2 files changed, 45 insertions(+), 16 deletions(-) diff --git a/xen/common/spinlock.c b/xen/common/spinlock.c index 6bc52d70c0..1be1b5ebe6 100644 --- a/xen/common/spinlock.c +++ b/xen/common/spinlock.c @@ -13,9 +13,9 @@ static atomic_t spin_debug __read_mostly = ATOMIC_INIT(0); -static void check_lock(struct lock_debug *debug) +static void check_lock(union lock_debug *debug) { - int irq_safe = !local_irq_is_enabled(); + bool irq_safe = !local_irq_is_enabled(); if ( unlikely(atomic_read(&spin_debug) <= 0) ) return; @@ -43,18 +43,21 @@ static void check_lock(struct lock_debug *debug) */ if ( unlikely(debug->irq_safe != irq_safe) ) { - int seen = cmpxchg(&debug->irq_safe, -1, irq_safe); + union lock_debug seen, new = { 0 }; - if ( seen == !irq_safe ) + new.irq_safe = irq_safe; + seen.val = cmpxchg(&debug->val, LOCK_DEBUG_INITVAL, new.val); + + if ( !seen.unseen && seen.irq_safe == !irq_safe ) { printk("CHECKLOCK FAILURE: prev irqsafe: %d, curr irqsafe %d\n", - seen, irq_safe); + seen.irq_safe, irq_safe); BUG(); } } } -static void check_barrier(struct lock_debug *debug) +static void check_barrier(union lock_debug *debug) { if ( unlikely(atomic_read(&spin_debug) <= 0) ) return; @@ -70,7 +73,18 @@ static void check_barrier(struct lock_debug *debug) * However, if we spin on an IRQ-unsafe lock with IRQs disabled then that * is clearly wrong, for the same reason outlined in check_lock() above. */ - BUG_ON(!local_irq_is_enabled() && (debug->irq_safe == 0)); + BUG_ON(!local_irq_is_enabled() && !debug->irq_safe); +} + +static void got_lock(union lock_debug *debug) +{ + debug->cpu = smp_processor_id(); +} + +static void rel_lock(union lock_debug *debug) +{ + ASSERT(debug->cpu == smp_processor_id()); + debug->cpu = SPINLOCK_NO_CPU; } void spin_debug_enable(void) @@ -87,6 +101,8 @@ void spin_debug_disable(void) #define check_lock(l) ((void)0) #define check_barrier(l) ((void)0) +#define got_lock(l) ((void)0) +#define rel_lock(l) ((void)0) #endif @@ -150,6 +166,7 @@ void inline _spin_lock_cb(spinlock_t *lock, void (*cb)(void *), void *data) cb(data); arch_lock_relax(); } + got_lock(&lock->debug); LOCK_PROFILE_GOT; preempt_disable(); arch_lock_acquire_barrier(); @@ -181,6 +198,7 @@ void _spin_unlock(spinlock_t *lock) arch_lock_release_barrier(); preempt_enable(); LOCK_PROFILE_REL; + rel_lock(&lock->debug); add_sized(&lock->tickets.head, 1); arch_lock_signal(); } @@ -224,6 +242,7 @@ int _spin_trylock(spinlock_t *lock) if ( cmpxchg(&lock->tickets.head_tail, old.head_tail, new.head_tail) != old.head_tail ) return 0; + got_lock(&lock->debug); #ifdef CONFIG_LOCK_PROFILE if (lock->profile) lock->profile->time_locked = NOW(); diff --git a/xen/include/xen/spinlock.h b/xen/include/xen/spinlock.h index 2c7415e23a..24405386a7 100644 --- a/xen/include/xen/spinlock.h +++ b/xen/include/xen/spinlock.h @@ -5,15 +5,24 @@ #include #include +#define SPINLOCK_CPU_BITS 12 + #ifndef NDEBUG -struct lock_debug { - s16 irq_safe; /* +1: IRQ-safe; 0: not IRQ-safe; -1: don't know yet */ +union lock_debug { + uint16_t val; +#define LOCK_DEBUG_INITVAL 0xffff + struct { + uint16_t cpu:SPINLOCK_CPU_BITS; + uint16_t :(14 - SPINLOCK_CPU_BITS); + bool irq_safe:1; + bool unseen:1; + }; }; -#define _LOCK_DEBUG { -1 } +#define _LOCK_DEBUG { LOCK_DEBUG_INITVAL } void spin_debug_enable(void); void spin_debug_disable(void); #else -struct lock_debug { }; +union lock_debug { }; #define _LOCK_DEBUG { } #define spin_debug_enable() ((void)0) #define spin_debug_disable() ((void)0) @@ -138,11 +147,12 @@ typedef union { typedef struct spinlock { spinlock_tickets_t tickets; - u16 recurse_cpu:12; -#define SPINLOCK_NO_CPU 0xfffu - u16 recurse_cnt:4; -#define SPINLOCK_MAX_RECURSE 0xfu - struct lock_debug debug; + u16 recurse_cpu:SPINLOCK_CPU_BITS; +#define SPINLOCK_NO_CPU ((1u << SPINLOCK_CPU_BITS) - 1) +#define SPINLOCK_RECURSE_BITS (16 - SPINLOCK_CPU_BITS) + u16 recurse_cnt:SPINLOCK_RECURSE_BITS; +#define SPINLOCK_MAX_RECURSE ((1u << SPINLOCK_RECURSE_BITS) - 1) + union lock_debug debug; #ifdef CONFIG_LOCK_PROFILE struct lock_profile *profile; #endif