From mboxrd@z Thu Jan 1 00:00:00 1970 From: tglx@linutronix.de (Thomas Gleixner) Date: Wed, 21 Dec 2016 19:32:06 +0100 (CET) Subject: ARM: imx: mmdc: Fix completely broken cpu hotplug code In-Reply-To: References: Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, 21 Dec 2016, Thomas Gleixner wrote: > The cpu hotplug support of this perf driver is broken in several ways: > > 1) It adds a instance before setting up the state. > > 2) The state for the instance is different from the state of the > callback. It's just a randomly chosen state. > > 3) The instance registration is not error checked so nobody noticed that > the call can never succeed. > > 4) The state for the multi install callbacks is chosen randomly and > overwrites existing state. This is now prevented by the core code so the > call is guaranteed to fail. > > 5) The error exit path in the init function leaves the instance registered > and then frees the memory which contains the enqueued hlist node. > > 6) The remove function is removing the state and not the instance. > > Fix it by: > > - Setting up the state before adding instances. Use a dynamically allocated > state for it. > > - Install instances after the state has been set up > > - Remove the instance in the error path before freeing memory > > - Remove instance not the state in the driver remove callback > > While at is use raw_cpu_processor_id(), because cpu_processor_id() cannot > be used in preemptible context, and set the driver data after successful > registration of the pmu. > > Fixes: e76bdfd7403a ("ARM: imx: Added perf functionality to mmdc driver") > Signed-off-by: Thomas Gleixner > Cc: Zhengyu Shen > Cc: Frank Li > Cc: Shawn Guo Shawn, as I have the final hotplug notifier removal pending here, which will break also the compilation of this driver, I would prefer to merge that through my tree before the removal patches to avoid build breakage. Thanks, tglx