From patchwork Tue Sep 29 10:57:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 290944 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B59FC4727C for ; Tue, 29 Sep 2020 12:09:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF61920674 for ; Tue, 29 Sep 2020 12:09:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601381351; bh=g7DBNqWBuOKWr4X+V2/6xXBxhvc+dSxZRRcjZFFx+iM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=byX8VqshpKd42iDQyFgcPHhvghduOBlTT5C4152D7Ohhg2G3VWyYy3eeMEWbXuXRM AfDr1q3YPtAqBfgMxrF6fc0zJyLwnECndWVWo4jXamcIjEkPo2GETogkhmgO12FNa7 KDKXduJaP1tR8UZEH1GpTFOdwz93GpQfcgUjeQaY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731749AbgI2MIz (ORCPT ); Tue, 29 Sep 2020 08:08:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:50012 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730220AbgI2Lhf (ORCPT ); Tue, 29 Sep 2020 07:37:35 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DA32C23B26; Tue, 29 Sep 2020 11:35:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601379359; bh=g7DBNqWBuOKWr4X+V2/6xXBxhvc+dSxZRRcjZFFx+iM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=r2wjnV608WkpOJxOv8HVhKhiUPChRXvR13jDRBB3lbp76o4JYnQ9mLJJFyNcR2MFC 98afC2KPcnJJApg/QfLU1E1FNdEeRrttCPswKYtxVSCRekiuqadNOSxp61LnIVrZ/Y UCf0lyVNrEGamFcARu+y9G7MKLi8v/LdcYsnH2kI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Waiman Long , "Peter Zijlstra (Intel)" , Ingo Molnar , Sasha Levin Subject: [PATCH 5.4 120/388] locking/lockdep: Decrement IRQ context counters when removing lock chain Date: Tue, 29 Sep 2020 12:57:31 +0200 Message-Id: <20200929110016.281330040@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200929110010.467764689@linuxfoundation.org> References: <20200929110010.467764689@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Waiman Long [ Upstream commit b3b9c187dc2544923a601733a85352b9ddaba9b3 ] There are currently three counters to track the IRQ context of a lock chain - nr_hardirq_chains, nr_softirq_chains and nr_process_chains. They are incremented when a new lock chain is added, but they are not decremented when a lock chain is removed. That causes some of the statistic counts reported by /proc/lockdep_stats to be incorrect. IRQ Fix that by decrementing the right counter when a lock chain is removed. Since inc_chains() no longer accesses hardirq_context and softirq_context directly, it is moved out from the CONFIG_TRACE_IRQFLAGS conditional compilation block. Fixes: a0b0fd53e1e6 ("locking/lockdep: Free lock classes that are no longer in use") Signed-off-by: Waiman Long Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lkml.kernel.org/r/20200206152408.24165-2-longman@redhat.com Signed-off-by: Sasha Levin --- kernel/locking/lockdep.c | 40 +++++++++++++++++------------- kernel/locking/lockdep_internals.h | 6 +++++ 2 files changed, 29 insertions(+), 17 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 9ab1a965c3b92..bca0f7f71cde4 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -2302,18 +2302,6 @@ static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, return 0; } -static void inc_chains(void) -{ - if (current->hardirq_context) - nr_hardirq_chains++; - else { - if (current->softirq_context) - nr_softirq_chains++; - else - nr_process_chains++; - } -} - #else static inline int check_irq_usage(struct task_struct *curr, @@ -2321,13 +2309,27 @@ static inline int check_irq_usage(struct task_struct *curr, { return 1; } +#endif /* CONFIG_TRACE_IRQFLAGS */ -static inline void inc_chains(void) +static void inc_chains(int irq_context) { - nr_process_chains++; + if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT) + nr_hardirq_chains++; + else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT) + nr_softirq_chains++; + else + nr_process_chains++; } -#endif /* CONFIG_TRACE_IRQFLAGS */ +static void dec_chains(int irq_context) +{ + if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT) + nr_hardirq_chains--; + else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT) + nr_softirq_chains--; + else + nr_process_chains--; +} static void print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv) @@ -2847,7 +2849,7 @@ static inline int add_chain_cache(struct task_struct *curr, hlist_add_head_rcu(&chain->entry, hash_head); debug_atomic_inc(chain_lookup_misses); - inc_chains(); + inc_chains(chain->irq_context); return 1; } @@ -3600,7 +3602,8 @@ lock_used: static inline unsigned int task_irq_context(struct task_struct *task) { - return 2 * !!task->hardirq_context + !!task->softirq_context; + return LOCK_CHAIN_HARDIRQ_CONTEXT * !!task->hardirq_context + + LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context; } static int separate_irq_context(struct task_struct *curr, @@ -4805,6 +4808,8 @@ recalc: return; /* Overwrite the chain key for concurrent RCU readers. */ WRITE_ONCE(chain->chain_key, chain_key); + dec_chains(chain->irq_context); + /* * Note: calling hlist_del_rcu() from inside a * hlist_for_each_entry_rcu() loop is safe. @@ -4826,6 +4831,7 @@ recalc: } *new_chain = *chain; hlist_add_head_rcu(&new_chain->entry, chainhashentry(chain_key)); + inc_chains(new_chain->irq_context); #endif } diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h index 18d85aebbb57f..a525368b8cf61 100644 --- a/kernel/locking/lockdep_internals.h +++ b/kernel/locking/lockdep_internals.h @@ -106,6 +106,12 @@ static const unsigned long LOCKF_USED_IN_IRQ_READ = #define STACK_TRACE_HASH_SIZE 16384 #endif +/* + * Bit definitions for lock_chain.irq_context + */ +#define LOCK_CHAIN_SOFTIRQ_CONTEXT (1 << 0) +#define LOCK_CHAIN_HARDIRQ_CONTEXT (1 << 1) + #define MAX_LOCKDEP_CHAINS (1UL << MAX_LOCKDEP_CHAINS_BITS) #define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)