From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Srivatsa S. Bhat" Subject: Re: [PATCH 25/45] staging/octeon: Use get/put_online_cpus_atomic() to prevent CPU offline Date: Mon, 24 Jun 2013 00:25:37 +0530 Message-ID: <51C744A9.8000406@linux.vnet.ibm.com> References: <20130623133642.19094.16038.stgit@srivatsabhat.in.ibm.com> <20130623134331.19094.80396.stgit@srivatsabhat.in.ibm.com> <20130623181740.GB24256@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: peterz@infradead.org, fweisbec@gmail.com, linux-kernel@vger.kernel.org, walken@google.com, mingo@kernel.org, linux-arch@vger.kernel.org, vincent.guittot@linaro.org, ddaney@caviumnetworks.com, xiaoguangrong@linux.vnet.ibm.com, wangyun@linux.vnet.ibm.com, paulmck@linux.vnet.ibm.com, devel@driverdev.osuosl.org, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, rusty@rustcorp.com.au, rostedt@goodmis.org, namhyung@kernel.org, tglx@linutronix.de, laijs@cn.fujitsu.com, zhong@linux.vnet.ibm.com, netdev@vger.kernel.org, oleg@redhat.com, sbw@mit.edu, tj@kernel.org, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org To: Greg Kroah-Hartman Return-path: In-Reply-To: <20130623181740.GB24256@kroah.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+glppe-linuxppc-embedded-2=m.gmane.org@lists.ozlabs.org Sender: "Linuxppc-dev" List-Id: netdev.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