From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x224RFfzd8zJvFxdUNqNn5uJdXEISo+hs8fhIYk4kk0H0aYbeG9fIdFY7nmg/uaHT/kgjW51t ARC-Seal: i=1; a=rsa-sha256; t=1518708706; cv=none; d=google.com; s=arc-20160816; b=YMX8FS6kXcQhAae/RPiSGq11EAYFVMcZ2w0JHyJiPyqXbW3No9ukzBQIgbPOBAaaqh C4It6ZethbeMo7YGj+T2Hw50fhSPsoJRDJL/z6zzMIL2RznafhlUTPXAekeSOcOdhbtb IZPONYPxHW1sChaInBzhwCeg++M6xlbS0vTo81Ntoo7aJFloYc6CUkQGdnGyZZDmSGeb Y5oKozZ1uDtjznXDy8m2jEhcGQej2G/S53QYDaUOBykUoH7ABVGveb7EycB+KT9WCX7/ KB9Z6mXJTc651xgHItDNbNbWdGstNYIn+gq9tJzYqCd3OjY/A9/pT/1TmBOk/2ImRM2l Humw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=AIuF5B2FAd38s3Jja57Xcla+IS8yb0XZqhQWJKeW7/k=; b=gpSMO6dexIjd65Hnuop1GMotHUjypLTd15w52r4AbmwWJ91mZK/UPH5Z5znL3bkPtv R9kaAXiM+RKXemaVlHb+4lFVulCVqXrp2Ueg3kRQwetyEhg9TNOPQgBCN3y4uGP8AIRd ZL04KQrSqnd7szvoRNUYQ67cexsKMk1g8vmNaJRR2364T4dik2603EQwJdAbyrUdjZ7x nmMXF+67IO5ZIo5mngpajlBv7GOFk6s6u2ReotOURSn1yI7jeinnQ5p28Zc0LcUiFpkL gMSxvlUnkEyyyMGyJ4xgrwQo87tQiR6bzjw2s2GS7RdTOJrP2epcoZCLnyesF6qlDg0e oC0A== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pavan Kondeti , "Steven Rostedt (VMware)" , "Peter Zijlstra (Intel)" , Andrew Morton , Linus Torvalds , Mike Galbraith , Thomas Gleixner , Ingo Molnar Subject: [PATCH 4.14 013/195] sched/rt: Use container_of() to get root domain in rto_push_irq_work_func() Date: Thu, 15 Feb 2018 16:15:04 +0100 Message-Id: <20180215151706.405191812@linuxfoundation.org> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180215151705.738773577@linuxfoundation.org> References: <20180215151705.738773577@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1592480996908357247?= X-GMAIL-MSGID: =?utf-8?q?1592481500936279453?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Steven Rostedt (VMware) commit ad0f1d9d65938aec72a698116cd73a980916895e upstream. When the rto_push_irq_work_func() is called, it looks at the RT overloaded bitmask in the root domain via the runqueue (rq->rd). The problem is that during CPU up and down, nothing here stops rq->rd from changing between taking the rq->rd->rto_lock and releasing it. That means the lock that is released is not the same lock that was taken. Instead of using this_rq()->rd to get the root domain, as the irq work is part of the root domain, we can simply get the root domain from the irq work that is passed to the routine: container_of(work, struct root_domain, rto_push_work) This keeps the root domain consistent. Reported-by: Pavan Kondeti Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 4bdced5c9a292 ("sched/rt: Simplify the IPI based RT balancing logic") Link: http://lkml.kernel.org/r/CAEU1=PkiHO35Dzna8EQqNSKW1fr1y1zRQ5y66X117MG06sQtNA@mail.gmail.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/sched/rt.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1907,9 +1907,8 @@ static void push_rt_tasks(struct rq *rq) * the rt_loop_next will cause the iterator to perform another scan. * */ -static int rto_next_cpu(struct rq *rq) +static int rto_next_cpu(struct root_domain *rd) { - struct root_domain *rd = rq->rd; int next; int cpu; @@ -1985,7 +1984,7 @@ static void tell_cpu_to_push(struct rq * * Otherwise it is finishing up and an ipi needs to be sent. */ if (rq->rd->rto_cpu < 0) - cpu = rto_next_cpu(rq); + cpu = rto_next_cpu(rq->rd); raw_spin_unlock(&rq->rd->rto_lock); @@ -1998,6 +1997,8 @@ static void tell_cpu_to_push(struct rq * /* Called from hardirq context */ void rto_push_irq_work_func(struct irq_work *work) { + struct root_domain *rd = + container_of(work, struct root_domain, rto_push_work); struct rq *rq; int cpu; @@ -2013,18 +2014,18 @@ void rto_push_irq_work_func(struct irq_w raw_spin_unlock(&rq->lock); } - raw_spin_lock(&rq->rd->rto_lock); + raw_spin_lock(&rd->rto_lock); /* Pass the IPI to the next rt overloaded queue */ - cpu = rto_next_cpu(rq); + cpu = rto_next_cpu(rd); - raw_spin_unlock(&rq->rd->rto_lock); + raw_spin_unlock(&rd->rto_lock); if (cpu < 0) return; /* Try the next RT overloaded CPU */ - irq_work_queue_on(&rq->rd->rto_push_work, cpu); + irq_work_queue_on(&rd->rto_push_work, cpu); } #endif /* HAVE_RT_PUSH_IPI */