From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932471AbdKONIg (ORCPT ); Wed, 15 Nov 2017 08:08:36 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:57725 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932361AbdKONIQ (ORCPT ); Wed, 15 Nov 2017 08:08:16 -0500 Date: Wed, 15 Nov 2017 14:08:12 +0100 From: Peter Zijlstra To: Martijn Coenen Cc: gregkh@linuxfoundation.org, john.stultz@linaro.org, tkjos@google.com, arve@android.com, sherryy@android.com, tglx@linutronix.de, amit.pundir@linaro.org, linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, maco@google.com Subject: Re: [PATCH v3 5/6] ANDROID: binder: don't check prio permissions on restore. Message-ID: <20171115130812.2xvbxfuyfq7opa7g@hirez.programming.kicks-ass.net> References: <20171026140750.119265-1-maco@android.com> <20171026140750.119265-6-maco@android.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171026140750.119265-6-maco@android.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 26, 2017 at 04:07:49PM +0200, Martijn Coenen wrote: > Because we have disabled RT priority inheritance for > the regular binder domain, the following can happen: > > 1) thread A (prio 98) calls into thread B > 2) because RT prio inheritance is disabled, thread B > runs at the lowest nice (prio 100) instead > 3) thread B calls back into A; A will run at prio 100 > for the duration of the transaction That sounds wrong.. Why would you ever downgrade A?