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Fri, 21 May 2021 06:46:32 -0700 (PDT) MIME-Version: 1.0 References: <20210504092340.00006c61@intel.com> <87pmxpdr32.ffs@nanos.tec.linutronix.de> <87im3gewlu.ffs@nanos.tec.linutronix.de> <87zgwo9u79.ffs@nanos.tec.linutronix.de> In-Reply-To: <87zgwo9u79.ffs@nanos.tec.linutronix.de> From: Nitesh Lal Date: Fri, 21 May 2021 09:46:20 -0400 Message-ID: Subject: Re: [PATCH tip:irq/core v1] genirq: remove auto-set of the mask when setting the hint To: Thomas Gleixner Cc: Jesse Brandeburg , Robin Murphy , Marcelo Tosatti , Ingo Molnar , linux-kernel@vger.kernel.org, intel-wired-lan@lists.osuosl.org, jbrandeb@kernel.org, "frederic@kernel.org" , "juri.lelli@redhat.com" , Alex Belits , "linux-api@vger.kernel.org" , "bhelgaas@google.com" , "linux-pci@vger.kernel.org" , "rostedt@goodmis.org" , "peterz@infradead.org" , "davem@davemloft.net" , "akpm@linux-foundation.org" , "sfr@canb.auug.org.au" , "stephen@networkplumber.org" , "rppt@linux.vnet.ibm.com" , "jinyuqi@huawei.com" , "zhangshaokun@hisilicon.com" , netdev@vger.kernel.org, chris.friesen@windriver.com, Marc Zyngier , Neil Horman , pjwaskiewicz@gmail.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 21, 2021 at 7:56 AM Thomas Gleixner wrote: > > Nitesh, > > On Thu, May 20 2021 at 20:03, Nitesh Lal wrote: > > On Thu, May 20, 2021 at 5:57 PM Nitesh Lal wrote: > >> I think here to ensure that we are not breaking any of the drivers we have > >> to first analyze all the existing drivers and understand how they are using > >> this API. > >> AFAIK there are three possible scenarios: > >> > >> - A driver use this API to spread the IRQs > >> + For this case we should be safe considering the spreading is naturally > >> done from the IRQ subsystem itself. > > > > Forgot to mention another thing in the above case is to determine whether > > it is true for all architectures or not as Thomas mentioned. > > Yes. > > >> > >> - A driver use this API to actually set the hint > >> + These drivers should have no functional impact because of this revert > > Correct. > > > >> - Driver use this API to force a certain affinity mask > >> + In this case we have to replace the API with the irq_force_affinity() > > irq_set_affinity() or irq_set_affinity_and_hint() Ah yes! my bad. _force_ doesn't check the mask against the online CPUs. Hmm, I didn't realize that you also added irq_set_affinity_and_hint() in your last patchset. > > >> I can start looking into the individual drivers, however, testing them will > >> be a challenge. > > The only way to do that is to have the core infrastructure added and Right. > then send patches changing it in the way you think. The relevant > maintainers/developers should be able to tell you when your analysis > went south. :) Ack will start looking into this. -- Thanks Nitesh