From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
To: paulmck@linux.vnet.ibm.com
Cc: tglx@linutronix.de, peterz@infradead.org, tj@kernel.org,
oleg@redhat.com, rusty@rustcorp.com.au, mingo@kernel.org,
akpm@linux-foundation.org, namhyung@kernel.org,
rostedt@goodmis.org, wangyun@linux.vnet.ibm.com,
xiaoguangrong@linux.vnet.ibm.com, rjw@sisk.pl, sbw@mit.edu,
fweisbec@gmail.com, linux@arm.linux.org.uk,
nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org,
linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 09/45] smp, cpu hotplug: Fix smp_call_function_*() to prevent CPU offline properly
Date: Mon, 11 Feb 2013 01:29:15 +0530 [thread overview]
Message-ID: <5117FC13.1030002@linux.vnet.ibm.com> (raw)
In-Reply-To: <20130210195639.GL2666@linux.vnet.ibm.com>
On 02/11/2013 01:26 AM, Paul E. McKenney wrote:
> On Mon, Feb 11, 2013 at 01:11:29AM +0530, Srivatsa S. Bhat wrote:
>> On 02/09/2013 05:37 AM, Paul E. McKenney wrote:
>>> On Tue, Jan 22, 2013 at 01:05:10PM +0530, Srivatsa S. Bhat wrote:
>>>> Once stop_machine() is gone from the CPU offline path, we won't be able to
>>>> depend on preempt_disable() to prevent CPUs from going offline from under us.
>>>>
>>>> Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline,
>>>> while invoking from atomic context.
>>>>
>>>> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
>>>
>>> Would it make sense for get_online_cpus_atomic() to return the current
>>> CPU number?
>>
>> Hmm, I'm not so sure. I tried to model it after get_online_cpus(), which doesn't
>> return anything (for other reasons, of course..)
>>
>> Moreover, a function name like *_cpu_* returning the CPU number would be intuitive.
>> But a name such as *_cpus_* (plural) returning a CPU number might appear confusing..
>>
>> And also I don't think it'll make a huge improvement in the callers.. (We might
>> be better off avoiding an smp_processor_id() if possible, since this function could
>> be called in very hot paths).. So I don't see a strong case for returning the
>> CPU number. But let me know if you think it'll still be worth it for some reason...
>
> I just noted a lot of two-line code sequences in your patch that would be
> one line if the CPU number was returned.
Ah, in that case, I'll reconsider your suggestion while working on the next version.
Thanks!
Regards,
Srivatsa S. Bhat
> But I don't feel strongly about
> it, so if people are OK with the current version, no problem.
>
> Thanx, Paul
>
next prev parent reply other threads:[~2013-02-10 20:01 UTC|newest]
Thread overview: 121+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-22 7:33 [PATCH v5 00/45] CPU hotplug: stop_machine()-free CPU hotplug Srivatsa S. Bhat
2013-01-22 7:33 ` [PATCH v5 01/45] percpu_rwlock: Introduce the global reader-writer lock backend Srivatsa S. Bhat
2013-01-22 18:45 ` Stephen Hemminger
2013-01-22 19:41 ` Srivatsa S. Bhat
2013-01-22 19:32 ` Steven Rostedt
2013-01-22 19:58 ` Srivatsa S. Bhat
2013-01-22 20:54 ` Steven Rostedt
2013-01-24 4:14 ` Michel Lespinasse
2013-01-22 7:33 ` [PATCH v5 02/45] percpu_rwlock: Introduce per-CPU variables for the reader and the writer Srivatsa S. Bhat
2013-01-22 7:33 ` [PATCH v5 03/45] percpu_rwlock: Provide a way to define and init percpu-rwlocks at compile time Srivatsa S. Bhat
2013-01-22 7:33 ` [PATCH v5 04/45] percpu_rwlock: Implement the core design of Per-CPU Reader-Writer Locks Srivatsa S. Bhat
2013-01-23 18:55 ` Tejun Heo
2013-01-23 19:33 ` Srivatsa S. Bhat
2013-01-23 19:57 ` Tejun Heo
2013-01-24 4:30 ` Srivatsa S. Bhat
2013-01-29 11:12 ` Namhyung Kim
2013-02-08 22:47 ` Paul E. McKenney
2013-02-10 18:38 ` Srivatsa S. Bhat
2013-02-08 23:10 ` Paul E. McKenney
2013-02-10 18:06 ` Oleg Nesterov
2013-02-10 19:24 ` Srivatsa S. Bhat
2013-02-10 19:50 ` Oleg Nesterov
2013-02-10 20:09 ` Srivatsa S. Bhat
2013-02-10 22:13 ` Paul E. McKenney
2013-02-10 19:54 ` Paul E. McKenney
2013-02-12 16:15 ` Paul E. McKenney
2013-02-10 19:10 ` Srivatsa S. Bhat
2013-02-10 19:47 ` Paul E. McKenney
2013-02-10 19:57 ` Srivatsa S. Bhat
2013-02-10 20:13 ` Oleg Nesterov
2013-02-10 20:20 ` Srivatsa S. Bhat
2013-01-22 7:34 ` [PATCH v5 05/45] percpu_rwlock: Make percpu-rwlocks IRQ-safe, optimally Srivatsa S. Bhat
2013-02-08 23:44 ` Paul E. McKenney
2013-02-10 19:27 ` Srivatsa S. Bhat
2013-02-10 18:42 ` Oleg Nesterov
2013-02-10 19:30 ` Srivatsa S. Bhat
2013-01-22 7:34 ` [PATCH v5 06/45] percpu_rwlock: Allow writers to be readers, and add lockdep annotations Srivatsa S. Bhat
2013-02-08 23:47 ` Paul E. McKenney
2013-02-10 19:32 ` Srivatsa S. Bhat
2013-01-22 7:34 ` [PATCH v5 07/45] CPU hotplug: Provide APIs to prevent CPU offline from atomic context Srivatsa S. Bhat
2013-01-29 10:21 ` Namhyung Kim
2013-02-10 19:34 ` Srivatsa S. Bhat
2013-02-08 23:50 ` Paul E. McKenney
2013-01-22 7:35 ` [PATCH v5 08/45] CPU hotplug: Convert preprocessor macros to static inline functions Srivatsa S. Bhat
2013-02-08 23:51 ` Paul E. McKenney
2013-01-22 7:35 ` [PATCH v5 09/45] smp, cpu hotplug: Fix smp_call_function_*() to prevent CPU offline properly Srivatsa S. Bhat
2013-02-09 0:07 ` Paul E. McKenney
2013-02-10 19:41 ` Srivatsa S. Bhat
2013-02-10 19:56 ` Paul E. McKenney
2013-02-10 19:59 ` Srivatsa S. Bhat [this message]
2013-01-22 7:35 ` [PATCH v5 10/45] smp, cpu hotplug: Fix on_each_cpu_*() " Srivatsa S. Bhat
2013-01-22 7:35 ` [PATCH v5 11/45] sched/timer: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-01-22 7:35 ` [PATCH v5 12/45] sched/migration: Use raw_spin_lock/unlock since interrupts are already disabled Srivatsa S. Bhat
2013-01-22 7:36 ` [PATCH v5 13/45] sched/rt: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-01-22 7:36 ` [PATCH v5 14/45] rcu, CPU hotplug: Fix comment referring to stop_machine() Srivatsa S. Bhat
2013-02-09 0:14 ` Paul E. McKenney
2013-02-10 19:43 ` Srivatsa S. Bhat
2013-01-22 7:36 ` [PATCH v5 15/45] tick: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-01-22 7:37 ` [PATCH v5 16/45] time/clocksource: " Srivatsa S. Bhat
2013-01-22 7:37 ` [PATCH v5 17/45] softirq: " Srivatsa S. Bhat
2013-01-22 7:38 ` [PATCH v5 18/45] irq: " Srivatsa S. Bhat
2013-01-22 7:38 ` [PATCH v5 19/45] net: " Srivatsa S. Bhat
2013-01-22 7:38 ` [PATCH v5 20/45] block: " Srivatsa S. Bhat
2013-01-22 7:38 ` [PATCH v5 21/45] crypto: pcrypt - Protect access to cpu_online_mask with get/put_online_cpus() Srivatsa S. Bhat
2013-01-22 7:39 ` [PATCH v5 22/45] infiniband: ehca: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-01-22 7:39 ` [PATCH v5 23/45] [SCSI] fcoe: " Srivatsa S. Bhat
2013-01-22 7:39 ` [PATCH v5 24/45] staging: octeon: " Srivatsa S. Bhat
2013-01-22 7:39 ` [PATCH v5 25/45] x86: " Srivatsa S. Bhat
2013-01-22 7:39 ` [PATCH v5 26/45] perf/x86: " Srivatsa S. Bhat
2013-01-22 7:40 ` [PATCH v5 27/45] KVM: Use get/put_online_cpus_atomic() to prevent CPU offline from atomic context Srivatsa S. Bhat
2013-01-22 7:40 ` [PATCH v5 28/45] kvm/vmx: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-01-22 7:40 ` [PATCH v5 29/45] x86/xen: " Srivatsa S. Bhat
2013-02-19 18:10 ` Konrad Rzeszutek Wilk
2013-02-19 18:29 ` Srivatsa S. Bhat
2013-01-22 7:41 ` [PATCH v5 30/45] alpha/smp: " Srivatsa S. Bhat
2013-01-22 7:41 ` [PATCH v5 31/45] blackfin/smp: " Srivatsa S. Bhat
2013-01-28 9:09 ` Bob Liu
2013-01-28 19:06 ` Tejun Heo
2013-01-29 1:14 ` Srivatsa S. Bhat
2013-01-22 7:41 ` [PATCH v5 32/45] cris/smp: " Srivatsa S. Bhat
2013-01-22 7:42 ` [PATCH v5 33/45] hexagon/smp: " Srivatsa S. Bhat
2013-01-22 7:42 ` [PATCH v5 34/45] ia64: " Srivatsa S. Bhat
2013-01-22 7:42 ` [PATCH v5 35/45] m32r: " Srivatsa S. Bhat
2013-01-22 7:42 ` [PATCH v5 36/45] MIPS: " Srivatsa S. Bhat
2013-01-22 7:43 ` [PATCH v5 37/45] mn10300: " Srivatsa S. Bhat
2013-01-22 7:43 ` [PATCH v5 38/45] parisc: " Srivatsa S. Bhat
2013-01-22 7:43 ` [PATCH v5 39/45] powerpc: " Srivatsa S. Bhat
2013-01-22 7:44 ` [PATCH v5 40/45] sh: " Srivatsa S. Bhat
2013-01-22 7:44 ` [PATCH v5 41/45] sparc: " Srivatsa S. Bhat
2013-01-22 7:44 ` [PATCH v5 42/45] tile: " Srivatsa S. Bhat
2013-01-22 7:44 ` [PATCH v5 43/45] cpu: No more __stop_machine() in _cpu_down() Srivatsa S. Bhat
2013-01-22 7:45 ` [PATCH v5 44/45] CPU hotplug, stop_machine: Decouple CPU hotplug from stop_machine() in Kconfig Srivatsa S. Bhat
2013-02-09 0:15 ` Paul E. McKenney
2013-02-10 19:45 ` Srivatsa S. Bhat
2013-01-22 7:45 ` [PATCH v5 45/45] Documentation/cpu-hotplug: Remove references to stop_machine() Srivatsa S. Bhat
2013-02-09 0:16 ` Paul E. McKenney
2013-02-04 13:47 ` [PATCH v5 00/45] CPU hotplug: stop_machine()-free CPU hotplug Srivatsa S. Bhat
2013-02-07 4:14 ` Rusty Russell
2013-02-07 6:11 ` Srivatsa S. Bhat
2013-02-08 15:41 ` Russell King - ARM Linux
2013-02-08 16:44 ` Srivatsa S. Bhat
2013-02-08 18:09 ` Srivatsa S. Bhat
2013-02-11 11:58 ` Vincent Guittot
2013-02-11 12:23 ` Srivatsa S. Bhat
2013-02-11 19:08 ` Paul E. McKenney
2013-02-12 3:58 ` Srivatsa S. Bhat
2013-02-15 13:28 ` Vincent Guittot
2013-02-15 19:40 ` Srivatsa S. Bhat
2013-02-18 10:24 ` Vincent Guittot
2013-02-18 10:34 ` Srivatsa S. Bhat
2013-02-18 10:51 ` Srivatsa S. Bhat
2013-02-18 10:58 ` Vincent Guittot
2013-02-18 15:30 ` Steven Rostedt
2013-02-18 16:50 ` Vincent Guittot
2013-02-18 19:53 ` Steven Rostedt
2013-02-18 19:53 ` Steven Rostedt
2013-02-19 10:33 ` Vincent Guittot
2013-02-18 10:54 ` Thomas Gleixner
2013-02-18 10:57 ` Srivatsa S. Bhat
2013-02-11 12:41 ` [PATCH v5 01/45] percpu_rwlock: Introduce the global reader-writer lock backend David Howells
2013-02-11 12:56 ` Srivatsa S. Bhat
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