From patchwork Wed Nov 2 20:30:49 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. 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McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, patches@linaro.org, "Paul E. McKenney" , "Paul E. McKenney" Subject: [PATCH RFC tip/core/rcu 28/28] rcu: Fix idle-task checks Date: Wed, 2 Nov 2011 13:30:49 -0700 Message-Id: <1320265849-5744-28-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.3.2 In-Reply-To: <20111102203017.GA3830@linux.vnet.ibm.com> References: <20111102203017.GA3830@linux.vnet.ibm.com> x-cbid: 11110220-5112-0000-0000-0000019EA3F0 From: Paul E. McKenney RCU has traditionally relied on idle_cpu() to determine whether a given CPU is running in the context of an idle task, but recent changes have invalidated this approach. This commit therefore switches from idle_cpu to "current->pid != 0". Reported-by: Wu Fengguang Suggested-by: Carsten Emde Signed-off-by: Paul E. McKenney Acked-by: Steven Rostedt Tested-by: Wu Fengguang Signed-off-by: Paul E. McKenney --- kernel/rcutiny.c | 4 ++-- kernel/rcutree.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index f4e7bc3..35f8a07 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -65,7 +65,7 @@ static void rcu_idle_enter_common(long long oldval) return; } RCU_TRACE(trace_rcu_dyntick("Start", oldval, rcu_dynticks_nesting)); - if (!idle_cpu(smp_processor_id())) { + if (current->pid != 0) { struct task_struct *idle = idle_task(smp_processor_id()); RCU_TRACE(trace_rcu_dyntick("Error on entry: not idle task", @@ -119,7 +119,7 @@ static void rcu_idle_exit_common(long long oldval) return; } RCU_TRACE(trace_rcu_dyntick("End", oldval, rcu_dynticks_nesting)); - if (!idle_cpu(smp_processor_id())) { + if (!current->pid != 0) { struct task_struct *idle = idle_task(smp_processor_id()); RCU_TRACE(trace_rcu_dyntick("Error on exit: not idle task", diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 3d7b474..414af68 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -355,7 +355,7 @@ static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval) return; } trace_rcu_dyntick("Start", oldval, rdtp->dynticks_nesting); - if (!idle_cpu(smp_processor_id())) { + if (current->pid != 0) { struct task_struct *idle = idle_task(smp_processor_id()); trace_rcu_dyntick("Error on entry: not idle task", @@ -449,7 +449,7 @@ static void rcu_idle_exit_common(struct rcu_dynticks *rdtp, long long oldval) smp_mb__after_atomic_inc(); /* See above. */ WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); trace_rcu_dyntick("End", oldval, rdtp->dynticks_nesting); - if (!idle_cpu(smp_processor_id())) { + if (current->pid != 0) { struct task_struct *idle = idle_task(smp_processor_id()); trace_rcu_dyntick("Error on exit: not idle task",