From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH v11 7/7] arm: pmu: Add PMU definitions for cores not initially online Date: Tue, 6 Dec 2016 15:21:18 +0000 Message-ID: <20161206152118.GK2498@arm.com> References: <1480704961-6910-1-git-send-email-jeremy.linton@arm.com> <1480704961-6910-8-git-send-email-jeremy.linton@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1480704961-6910-8-git-send-email-jeremy.linton@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Jeremy Linton Cc: mark.rutland@arm.com, steve.capper@arm.com, mlangsdorf@redhat.com, punit.agrawal@arm.com, linux@armlinux.org.uk, linux-acpi@vger.kernel.org, msalter@redhat.com, linux-arm-kernel@lists.infradead.org List-Id: linux-acpi@vger.kernel.org On Fri, Dec 02, 2016 at 12:56:01PM -0600, Jeremy Linton wrote: > ACPI CPUs aren't associated with a PMU until they have been put > online. This means that we potentially have to update a PMU > definition the first time a CPU is hot added to the machine. > > Signed-off-by: Jeremy Linton > --- > drivers/perf/arm_pmu.c | 38 ++++++++++++++++++++++++++++++++++++-- > include/linux/perf/arm_pmu.h | 4 ++++ > 2 files changed, 40 insertions(+), 2 deletions(-) > > diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c > index fa40294..4abb2fe 100644 > --- a/drivers/perf/arm_pmu.c > +++ b/drivers/perf/arm_pmu.c > @@ -711,6 +711,30 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler) > return 0; > } > > +static DEFINE_SPINLOCK(arm_pmu_resource_lock); Why do you need this spinlock? The hotplug notifiers are serialised afaik, and you don't take it anywhere else. Will