Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750955Ab3FWSRq (ORCPT ); Sun, 23 Jun 2013 14:17:46 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:48057 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750779Ab3FWSRm (ORCPT ); Sun, 23 Jun 2013 14:17:42 -0400 Date: Sun, 23 Jun 2013 11:17:40 -0700 From: Greg Kroah-Hartman To: "Srivatsa S. Bhat" Cc: tglx@linutronix.de, peterz@infradead.org, tj@kernel.org, oleg@redhat.com, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org, walken@google.com, vincent.guittot@linaro.org, laijs@cn.fujitsu.com, rostedt@goodmis.org, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, sbw@mit.edu, fweisbec@gmail.com, zhong@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org Subject: Re: [PATCH 25/45] staging/octeon: Use get/put_online_cpus_atomic() to prevent CPU offline Message-ID: <20130623181740.GB24256@kroah.com> References: <20130623133642.19094.16038.stgit@srivatsabhat.in.ibm.com> <20130623134331.19094.80396.stgit@srivatsabhat.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130623134331.19094.80396.stgit@srivatsabhat.in.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1892 Lines: 54 On Sun, Jun 23, 2013 at 07:13:33PM +0530, Srivatsa S. Bhat wrote: > 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. > > Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going > offline, while invoking from atomic context. > > Cc: Greg Kroah-Hartman > Cc: devel@driverdev.osuosl.org > Signed-off-by: Srivatsa S. Bhat > --- > > drivers/staging/octeon/ethernet-rx.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/staging/octeon/ethernet-rx.c b/drivers/staging/octeon/ethernet-rx.c > index 34afc16..8588b4d 100644 > --- a/drivers/staging/octeon/ethernet-rx.c > +++ b/drivers/staging/octeon/ethernet-rx.c > @@ -36,6 +36,7 @@ > #include > #include > #include > +#include > #include > #include > #ifdef CONFIG_XFRM > @@ -97,6 +98,7 @@ static void cvm_oct_enable_one_cpu(void) > return; > > /* ... if a CPU is available, Turn on NAPI polling for that CPU. */ > + get_online_cpus_atomic(); > for_each_online_cpu(cpu) { > if (!cpu_test_and_set(cpu, core_state.cpu_state)) { > v = smp_call_function_single(cpu, cvm_oct_enable_napi, > @@ -106,6 +108,7 @@ static void cvm_oct_enable_one_cpu(void) > break; > } > } > + put_online_cpus_atomic(); Does this driver really need to be doing this in the first place? If so, why? The majority of network drivers don't, why is this one "special"? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/