Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline

[PATCH v2 00/45] CPU hotplug: stop_machine()-free CPU hotplug, part 1 · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 01/45] CPU hotplug: Provide APIs to prevent CPU offline from atomic context · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 02/45] CPU hotplug: Clarify the usage of different synchronization APIs · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 03/45] Documentation, CPU hotplug: Recommend usage of get/put_online_cpus_atomic() · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 04/45] CPU hotplug: Add infrastructure to check lacking hotplug synchronization · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 05/45] CPU hotplug: Protect set_cpu_online() to avoid false-positives · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 07/45] CPU hotplug: Expose the new debug config option · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 08/45] CPU hotplug: Convert preprocessor macros to static inline functions · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 09/45] smp: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 10/45] sched/core: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 12/45] sched/fair: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 11/45] migration: Use raw_spin_lock/unlock since interrupts are already disabled · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 13/45] timer: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 14/45] sched/rt: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Paul E. McKenney <hidden> · 2013-06-25
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-26
RE: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · David Laight <hidden> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Paul E. McKenney <hidden> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Steven Rostedt <rostedt@goodmis.org> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Tejun Heo <tj@kernel.org> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Steven Rostedt <rostedt@goodmis.org> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Tejun Heo <tj@kernel.org> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Tejun Heo <tj@kernel.org> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-27
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-26
RE: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · David Laight <hidden> · 2013-06-27
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-27
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Paul E. McKenney <hidden> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-26
Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline · Paul E. McKenney <hidden> · 2013-06-26
[PATCH v2 16/45] tick-broadcast: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 17/45] time/clocksource: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 18/45] softirq: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 19/45] irq: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 20/45] net: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 21/45] block: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 22/45] percpu_counter: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 24/45] [SCSI] fcoe: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 25/45] staging/octeon: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
Re: [PATCH v2 25/45] staging/octeon: Use get/put_online_cpus_atomic() to prevent CPU offline · Greg Kroah-Hartman <gregkh@linuxfoundation.org> · 2013-06-25
[PATCH v2 27/45] perf/x86: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 29/45] kvm/vmx: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
Re: [PATCH v2 29/45] kvm/vmx: Use get/put_online_cpus_atomic() to prevent CPU offline · Paolo Bonzini <pbonzini@redhat.com> · 2013-06-26
Re: [PATCH v2 29/45] kvm/vmx: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-26
Re: [PATCH v2 29/45] kvm/vmx: Use get/put_online_cpus_atomic() to prevent CPU offline · Paolo Bonzini <pbonzini@redhat.com> · 2013-06-26
Re: [PATCH v2 29/45] kvm/vmx: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-26
Re: [PATCH v2 29/45] kvm/vmx: Use get/put_online_cpus_atomic() to prevent CPU offline · Paolo Bonzini <pbonzini@redhat.com> · 2013-06-26
[PATCH v2 30/45] x86/xen: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 31/45] alpha/smp: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 32/45] blackfin/smp: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 33/45] cris/smp: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 34/45] hexagon/smp: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 35/45] ia64: irq, perfmon: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 36/45] ia64: smp, tlb: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 37/45] m32r: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 38/45] MIPS: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
Re: [PATCH v2 38/45] MIPS: Use get/put_online_cpus_atomic() to prevent CPU offline · Ralf Baechle <hidden> · 2013-06-26
Re: [PATCH v2 38/45] MIPS: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-27
[PATCH v2 39/45] mn10300: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 40/45] powerpc, irq: Use GFP_ATOMIC allocations in atomic context · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 41/45] powerpc: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 42/45] powerpc: Use get/put_online_cpus_atomic() to avoid false-positive warning · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 43/45] sh: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 44/45] sparc: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 45/45] tile: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 28/45] KVM: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
Re: [PATCH v2 28/45] KVM: Use get/put_online_cpus_atomic() to prevent CPU offline · Paolo Bonzini <pbonzini@redhat.com> · 2013-06-26
[PATCH v2 26/45] x86: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 23/45] infiniband: ehca: Use get/put_online_cpus_atomic() to prevent CPU offline · Srivatsa S. Bhat <hidden> · 2013-06-25
[PATCH v2 06/45] CPU hotplug: Sprinkle debugging checks to catch locking bugs · Srivatsa S. Bhat <hidden> · 2013-06-25

From: Steven Rostedt <rostedt@goodmis.org>
Date: 2013-06-26 14:51:22
Also in: linux-arch, linux-pm, lkml, netdev

On Wed, 2013-06-26 at 07:34 -0700, Paul E. McKenney wrote:

On Wed, Jun 26, 2013 at 03:29:40PM +0100, David Laight wrote:

quoted

Once stop_machine() is gone from the CPU offline path, we won't be able
to depend on disabling preemption to prevent CPUs from going offline
from under us.

Could you use an rcu-like sequence so that disabling pre-emption
would be enough?

Something like rebuilding the cpu list, then forcing yourself
to run on all the cpu.

That would be far less intrusive.

It would also increase the latency of CPU-hotunplug operations.

Is that a big deal?

-- Steve

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