From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>,
Corey Ashford <cjashfor@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: [PATCH 5/7] perf_counter: fix the output lock
Date: Tue, 05 May 2009 17:50:25 +0200 [thread overview]
Message-ID: <20090505155437.232686598@chello.nl> (raw)
In-Reply-To: 20090505155020.309162852@chello.nl
[-- Attachment #1: perf_counter-fix-output-lock.patch --]
[-- Type: text/plain, Size: 1348 bytes --]
Use -1 instead of 0 as unlocked, since 0 is a valid cpu number.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
kernel/perf_counter.c | 39 ++++++++++++++++++++++++++++++++++-----
1 file changed, 34 insertions(+), 5 deletions(-)
Index: linux-2.6/kernel/perf_counter.c
===================================================================
--- linux-2.6.orig/kernel/perf_counter.c
+++ linux-2.6/kernel/perf_counter.c
@@ -1409,6 +1417,7 @@ static int perf_mmap_data_alloc(struct p
}
data->nr_pages = nr_pages;
+ atomic_set(&data->lock, -1);
rcu_assign_pointer(counter->data, data);
@@ -1755,7 +1764,7 @@ static void perf_output_lock(struct perf
if (in_nmi() && atomic_read(&data->lock) == cpu)
return;
- while (atomic_cmpxchg(&data->lock, 0, cpu) != 0)
+ while (atomic_cmpxchg(&data->lock, -1, cpu) != -1)
cpu_relax();
handle->locked = 1;
@@ -1784,7 +1793,7 @@ again:
* NMI can happen here, which means we can miss a done_head update.
*/
- cpu = atomic_xchg(&data->lock, 0);
+ cpu = atomic_xchg(&data->lock, -1);
WARN_ON_ONCE(cpu != smp_processor_id());
/*
@@ -1794,7 +1803,7 @@ again:
/*
* Since we had it locked, we can lock it again.
*/
- while (atomic_cmpxchg(&data->lock, 0, cpu) != 0)
+ while (atomic_cmpxchg(&data->lock, -1, cpu) != -1)
cpu_relax();
goto again;
--
next prev parent reply other threads:[~2009-05-05 16:18 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-05 15:50 [PATCH 0/7] pending sched and perf_counter patches Peter Zijlstra
2009-05-05 15:50 ` [PATCH 1/7] sched: rt: document the risk of small values in the bandwidth settings Peter Zijlstra
2009-05-05 18:33 ` [tip:sched/core] " tip-bot for Peter Zijlstra
2009-05-05 15:50 ` [PATCH 2/7] perf_counter: uncouple data_head updates from wakeups Peter Zijlstra
2009-05-05 18:34 ` [tip:perfcounters/core] " tip-bot for Peter Zijlstra
2009-05-05 15:50 ` [PATCH 3/7] perf_counter: ioctl(PERF_COUNTER_IOC_RESET) Peter Zijlstra
2009-05-05 18:31 ` Corey Ashford
2009-05-05 18:42 ` Peter Zijlstra
2009-05-05 19:31 ` Ingo Molnar
2009-05-05 18:34 ` [tip:perfcounters/core] perf_counter: add ioctl(PERF_COUNTER_IOC_RESET) tip-bot for Peter Zijlstra
2009-05-05 15:50 ` [PATCH 4/7] perf_counter: provide an mlock threshold Peter Zijlstra
2009-05-05 18:34 ` [tip:perfcounters/core] " tip-bot for Peter Zijlstra
2009-05-05 15:50 ` Peter Zijlstra [this message]
2009-05-05 18:34 ` [tip:perfcounters/core] perf_counter: fix the output lock tip-bot for Peter Zijlstra
2009-05-05 15:50 ` [PATCH 6/7] perf_counter: inheritable sample counters Peter Zijlstra
2009-05-05 18:34 ` [tip:perfcounters/core] " tip-bot for Peter Zijlstra
2009-05-05 15:50 ` [PATCH 7/7] perf_counter: tools: update the tools to support process and inherited counters Peter Zijlstra
2009-05-05 18:34 ` [tip:perfcounters/core] " tip-bot for Peter Zijlstra
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