From: Peter Zijlstra <peterz@infradead.org>
To: Arjan van de Ven <arjan@linux.intel.com>
Cc: lenb@kernel.org, rjw@rjwysocki.net, linux-acpi@vger.kernel.org,
linux-kernel@vger.kernel.org, shaohua.li@intel.com,
rui.zhang@intel.com, jacob.jun.pan@linux.intel.com,
Mike Galbraith <bitbucket@online.de>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
hpa@zytor.com
Subject: Re: [PATCH] x86, acpi, idle: Restructure the mwait idle routines
Date: Tue, 19 Nov 2013 16:13:38 +0100 [thread overview]
Message-ID: <20131119151338.GF3694@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20131119145143.GK10022@twins.programming.kicks-ass.net>
On Tue, Nov 19, 2013 at 03:51:43PM +0100, Peter Zijlstra wrote:
> That said, that drive is completely wrecked. It uses
> preempt_enable_no_resched() wrong too, it has uncommented barriers..
>
> Dude, wtf are you guys smoking?
---
Subject: sched: Take away preempt_enable_no_resched() and friends from modules
There is no way in hell modules are going to play preemption tricks like
this.
Cc: eliezer.tamir@linux.intel.com
Cc: arjan@linux.intel.com
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
---
drivers/thermal/intel_powerclamp.c | 2 +-
include/linux/preempt.h | 8 +++++++-
include/net/busy_poll.h | 15 +++------------
3 files changed, 11 insertions(+), 14 deletions(-)
diff --git a/drivers/thermal/intel_powerclamp.c b/drivers/thermal/intel_powerclamp.c
index 8f181b3f842b..0a12ddc2eb4c 100644
--- a/drivers/thermal/intel_powerclamp.c
+++ b/drivers/thermal/intel_powerclamp.c
@@ -445,7 +445,7 @@ static int clamp_thread(void *arg)
atomic_inc(&idle_wakeup_counter);
}
tick_nohz_idle_exit();
- preempt_enable_no_resched();
+ preempt_enable();
}
del_timer_sync(&wakeup_timer);
clear_bit(cpunr, cpu_clamping_mask);
diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index a3d9dc8c2c00..3ed2b5335ab4 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -64,7 +64,7 @@ do { \
} while (0)
#else
-#define preempt_enable() preempt_enable_no_resched()
+#define preempt_enable() sched_preempt_enable_no_resched()
#define preempt_check_resched() do { } while (0)
#endif
@@ -116,6 +116,12 @@ do { \
#endif /* CONFIG_PREEMPT_COUNT */
+#ifdef MODULE
+#undef preempt_enable_no_resched
+#undef preempt_enable_no_resched_notrace
+#undef preempt_check_resched
+#endif
+
#ifdef CONFIG_PREEMPT_NOTIFIERS
struct preempt_notifier;
diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h
index 829627d7b846..756827a86c2d 100644
--- a/include/net/busy_poll.h
+++ b/include/net/busy_poll.h
@@ -42,27 +42,18 @@ static inline bool net_busy_loop_on(void)
return sysctl_net_busy_poll;
}
-/* a wrapper to make debug_smp_processor_id() happy
- * we can use sched_clock() because we don't care much about precision
- * we only care that the average is bounded
- */
-#ifdef CONFIG_DEBUG_PREEMPT
static inline u64 busy_loop_us_clock(void)
{
u64 rc;
+ /* XXX with interrupts enabled sched_clock() can return utter garbage */
+
preempt_disable_notrace();
rc = sched_clock();
- preempt_enable_no_resched_notrace();
+ preempt_enable_notrace();
return rc >> 10;
}
-#else /* CONFIG_DEBUG_PREEMPT */
-static inline u64 busy_loop_us_clock(void)
-{
- return sched_clock() >> 10;
-}
-#endif /* CONFIG_DEBUG_PREEMPT */
static inline unsigned long sk_busy_loop_end_time(struct sock *sk)
{
next prev parent reply other threads:[~2013-11-19 15:13 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-19 9:00 acpi_pad mwait usage Peter Zijlstra
2013-11-19 9:08 ` Peter Zijlstra
2013-11-19 11:31 ` [PATCH] x86, acpi, idle: Restructure the mwait idle routines Peter Zijlstra
2013-11-19 13:06 ` Rafael J. Wysocki
2013-11-19 13:21 ` Mike Galbraith
2013-11-19 14:22 ` Arjan van de Ven
2013-11-19 14:46 ` Peter Zijlstra
2013-11-19 14:51 ` Peter Zijlstra
2013-11-19 15:13 ` Peter Zijlstra [this message]
2013-11-19 21:06 ` Jacob Pan
2013-11-20 10:28 ` Peter Zijlstra
2013-11-20 10:58 ` Peter Zijlstra
2013-11-20 16:24 ` Arjan van de Ven
2013-11-20 16:33 ` Peter Zijlstra
2013-11-20 16:38 ` Arjan van de Ven
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