From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Auger Subject: Re: [RFC v2 3/6] irq: bypass: Extend skeleton for ARM forwarding control Date: Mon, 06 Jul 2015 19:09:00 +0200 Message-ID: <559AB62C.9000503@linaro.org> References: <1436184692-20927-1-git-send-email-eric.auger@linaro.org> <1436184692-20927-4-git-send-email-eric.auger@linaro.org> <559A7425.4050506@redhat.com> <559AA02A.6060703@linaro.org> <559AA552.3010400@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, patches@linaro.org To: Paolo Bonzini , eric.auger@st.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, christoffer.dall@linaro.org, marc.zyngier@arm.com, alex.williamson@redhat.com, avi.kivity@gmail.com, mtosatti@redhat.com, feng.wu@intel.com, joro@8bytes.org, b.reynal@virtualopensystems.com Return-path: In-Reply-To: <559AA552.3010400@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu List-Id: kvm.vger.kernel.org On 07/06/2015 05:57 PM, Paolo Bonzini wrote: > > > On 06/07/2015 17:35, Eric Auger wrote: >>>> diff --git a/kernel/irq/bypass.c b/kernel/irq/bypass.c >>>>>> index 5d0f92b..efadbe5 100644 >>>>>> --- a/kernel/irq/bypass.c >>>>>> +++ b/kernel/irq/bypass.c >>>>>> @@ -19,6 +19,42 @@ static LIST_HEAD(producers); >>>>>> static LIST_HEAD(consumers); >>>>>> static DEFINE_MUTEX(lock); >>>>>> >>>>>> +/* lock must be hold when calling connect */ >>>> >>>> If a lock must be held while callbacks are called, you have to document >>>> that producers and consumers must _not_ call back into the IRQ bypass >>>> manager. (If they have to, you have to document explicitly "This >>>> function can be called from producer and consumer callbacks" whenever >>>> relevant). >> OK Thanks > > Also, please document on functions that take the irq bypass mutex that > they can sleep. In fact irq_bypass_{,un}register_{producer,consumer} > need kerneldoc comments. > > The good thing is that this helps a bit forming a lock hierarchy across > the subsystems, for example irq bypass mutex outside vfio_platform_irq > spinlock, because you cannot have a spinlock inside the mutex. I think > that all of your six callbacks are fine. arghh, no that's wrong then. I have plenty of them in the KVM/arm vgic part :-( Eric > > Paolo >