From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751697Ab3FWS7K (ORCPT ); Sun, 23 Jun 2013 14:59:10 -0400 Received: from e23smtp07.au.ibm.com ([202.81.31.140]:39184 "EHLO e23smtp07.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750841Ab3FWS7G (ORCPT ); Sun, 23 Jun 2013 14:59:06 -0400 Message-ID: <51C744A9.8000406@linux.vnet.ibm.com> Date: Mon, 24 Jun 2013 00:25:37 +0530 From: "Srivatsa S. Bhat" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120828 Thunderbird/15.0 MIME-Version: 1.0 To: Greg Kroah-Hartman 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, ddaney@caviumnetworks.com Subject: Re: [PATCH 25/45] staging/octeon: Use get/put_online_cpus_atomic() to prevent CPU offline References: <20130623133642.19094.16038.stgit@srivatsabhat.in.ibm.com> <20130623134331.19094.80396.stgit@srivatsabhat.in.ibm.com> <20130623181740.GB24256@kroah.com> In-Reply-To: <20130623181740.GB24256@kroah.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13062318-0260-0000-0000-000003342980 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/23/2013 11:47 PM, Greg Kroah-Hartman wrote: > 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"? > Honestly, I don't know. Let's CC the author of that code (David Daney). I wonder why get_maintainer.pl didn't generate his name for this file, even though the entire file is almost made up of his commits alone! Regards, Srivatsa S. Bhat