From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754421AbdKKIQG (ORCPT ); Sat, 11 Nov 2017 03:16:06 -0500 Received: from mail-wr0-f193.google.com ([209.85.128.193]:53589 "EHLO mail-wr0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751134AbdKKIQE (ORCPT ); Sat, 11 Nov 2017 03:16:04 -0500 X-Google-Smtp-Source: AGs4zMY/QAWKErw7SvrptsZpuaBimUGYc5oRZ5kqBAHRgF/EtEktxyk0LRGVC690jKmSeQEZH3NDhQ== Date: Sat, 11 Nov 2017 09:16:00 +0100 From: Ingo Molnar To: David Miller Cc: josef@toxicpanda.com, rostedt@goodmis.org, mingo@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, ast@kernel.org, kernel-team@fb.com, daniel@iogearbox.net Subject: Re: [PATCH 0/2][v5] Add the ability to do BPF directed error injection Message-ID: <20171111081600.ur3bkm5qyiomlpfa@gmail.com> References: <1510086523-8859-1-git-send-email-josef@toxicpanda.com> <20171111.121830.2006427570087282446.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171111.121830.2006427570087282446.davem@davemloft.net> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * David Miller wrote: > From: Josef Bacik > Date: Tue, 7 Nov 2017 15:28:41 -0500 > > > I'm sending this through Dave since it'll conflict with other BPF changes in his > > tree, but since it touches tracing as well Dave would like a review from > > somebody on the tracing side. > ... > > A lot of our error paths are not well tested because we have no good way of > > injecting errors generically. Some subystems (block, memory) have ways to > > inject errors, but they are random so it's hard to get reproduceable results. > > > > With BPF we can add determinism to our error injection. We can use kprobes and > > other things to verify we are injecting errors at the exact case we are trying > > to test. This patch gives us the tool to actual do the error injection part. > > It is very simple, we just set the return value of the pt_regs we're given to > > whatever we provide, and then override the PC with a dummy function that simply > > returns. > > > > Right now this only works on x86, but it would be simple enough to expand to > > other architectures. Thanks, > > Series applied, thanks Josef. Please don't apply it yet as the series is still under active discussion - for now I'm NAK-ing the x86 bits because I have second thoughts about the whole premise of the feature being added here. Thanks, Ingo