From: Peter Zijlstra <peterz@infradead•org>
To: "Srivatsa S. Bhat" <srivatsa.bhat@linux•vnet.ibm.com>
Cc: Stephen Warren <swarren@wwwdotorg•org>,
Frederic Weisbecker <fweisbec@gmail•com>,
LKML <linux-kernel@vger•kernel.org>,
Andrew Morton <akpm@linux-foundation•org>,
Eric Dumazet <eric.dumazet@gmail•com>,
Ingo Molnar <mingo@kernel•org>, Kevin Hilman <khilman@linaro•org>,
"Paul E. McKenney" <paulmck@linux•vnet.ibm.com>,
Thomas Gleixner <tglx@linutronix•de>,
Viresh Kumar <viresh.kumar@linaro•org>,
"linux-next@vger•kernel.org" <linux-next@vger•kernel.org>
Subject: Re: [PATCH 2/6] irq_work: Implement remote queueing
Date: Wed, 25 Jun 2014 12:19:15 +0200 [thread overview]
Message-ID: <20140625101915.GO19860@laptop.programming.kicks-ass.net> (raw)
In-Reply-To: <53AA9C43.3020903@linux.vnet.ibm.com>
On Wed, Jun 25, 2014 at 03:24:11PM +0530, Srivatsa S. Bhat wrote:
> Wait, that was a stupid idea. hotplug_cfd() already invokes irq_work_run
> indirectly via flush_smp_call_function_queue(). So irq_work_cpu_notify()
> doesn't need to invoke it again, AFAIU. So perhaps we can get rid of
> irq_work_cpu_notify() altogether?
Just so...
getting up at 6am and sitting in an airport terminal doesn't seem to
agree with me; any more silly fail here?
---
Subject: irq_work: Remove BUG_ON in irq_work_run()
From: Peter Zijlstra <peterz@infradead•org>
Date: Wed Jun 25 07:13:07 CEST 2014
Because of a collision with 8d056c48e486 ("CPU hotplug, smp: flush any
pending IPI callbacks before CPU offline"), which ends up calling
hotplug_cfd()->flush_smp_call_function_queue()->irq_work_run(), which
is not from IRQ context.
And since that already calls irq_work_run() from the hotplug path,
remove our entire hotplug handling.
Cc: Frederic Weisbecker <fweisbec@gmail•com>
Reported-by: Stephen Warren <swarren@wwwdotorg•org>
Signed-off-by: Peter Zijlstra <peterz@infradead•org>
Link: http://lkml.kernel.org/n/tip-busatzs2gvz4v62258agipuf@git.kernel.org
---
kernel/irq_work.c | 48 +++++-------------------------------------------
1 file changed, 5 insertions(+), 43 deletions(-)
Index: linux-2.6/kernel/irq_work.c
===================================================================
--- linux-2.6.orig/kernel/irq_work.c
+++ linux-2.6/kernel/irq_work.c
@@ -160,20 +160,14 @@ static void irq_work_run_list(struct lli
}
}
-static void __irq_work_run(void)
-{
- irq_work_run_list(&__get_cpu_var(raised_list));
- irq_work_run_list(&__get_cpu_var(lazy_list));
-}
-
/*
- * Run the irq_work entries on this cpu. Requires to be ran from hardirq
- * context with local IRQs disabled.
+ * hotplug calls this through:
+ * hotplug_cfs() -> flush_smp_call_function_queue()
*/
-void irq_work_run(void)
+static void irq_work_run(void)
{
- BUG_ON(!in_irq());
- __irq_work_run();
+ irq_work_run_list(&__get_cpu_var(raised_list));
+ irq_work_run_list(&__get_cpu_var(lazy_list));
}
EXPORT_SYMBOL_GPL(irq_work_run);
@@ -189,35 +183,3 @@ void irq_work_sync(struct irq_work *work
cpu_relax();
}
EXPORT_SYMBOL_GPL(irq_work_sync);
-
-#ifdef CONFIG_HOTPLUG_CPU
-static int irq_work_cpu_notify(struct notifier_block *self,
- unsigned long action, void *hcpu)
-{
- long cpu = (long)hcpu;
-
- switch (action) {
- case CPU_DYING:
- /* Called from stop_machine */
- if (WARN_ON_ONCE(cpu != smp_processor_id()))
- break;
- __irq_work_run();
- break;
- default:
- break;
- }
- return NOTIFY_OK;
-}
-
-static struct notifier_block cpu_notify;
-
-static __init int irq_work_init_cpu_notifier(void)
-{
- cpu_notify.notifier_call = irq_work_cpu_notify;
- cpu_notify.priority = 0;
- register_cpu_notifier(&cpu_notify);
- return 0;
-}
-device_initcall(irq_work_init_cpu_notifier);
-
-#endif /* CONFIG_HOTPLUG_CPU */
next prev parent reply other threads:[~2014-06-25 10:19 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1402413309-3415-1-git-send-email-fweisbec@gmail.com>
[not found] ` <1402413309-3415-3-git-send-email-fweisbec@gmail.com>
2014-06-24 20:33 ` [PATCH 2/6] irq_work: Implement remote queueing Stephen Warren
2014-06-24 20:35 ` Stephen Warren
2014-06-25 5:12 ` Peter Zijlstra
2014-06-25 5:17 ` Peter Zijlstra
2014-06-25 6:37 ` Srivatsa S. Bhat
2014-06-25 9:36 ` Peter Zijlstra
2014-06-25 9:39 ` Peter Zijlstra
2014-06-25 9:50 ` Srivatsa S. Bhat
2014-06-25 9:54 ` Srivatsa S. Bhat
2014-06-25 10:19 ` Peter Zijlstra [this message]
2014-06-25 10:57 ` Srivatsa S. Bhat
2014-06-25 16:23 ` Stephen Warren
2014-06-25 16:38 ` Peter Zijlstra
2014-06-25 16:57 ` Srivatsa S. Bhat
2014-06-28 18:19 ` Borislav Petkov
2014-07-03 14:52 ` Frederic Weisbecker
2014-07-04 5:10 ` Sachin Kamat
2014-07-01 19:13 ` Stephen Warren
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