From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932165AbbJaAEH (ORCPT ); Fri, 30 Oct 2015 20:04:07 -0400 Received: from mail-pa0-f53.google.com ([209.85.220.53]:34091 "EHLO mail-pa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752455AbbJaAEF (ORCPT ); Fri, 30 Oct 2015 20:04:05 -0400 Date: Fri, 30 Oct 2015 17:03:58 -0700 From: Alexei Starovoitov To: Yang Shi Cc: ast@kernel.org, rostedt@goodmis.org, linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org, netdev@vger.kernel.org, linaro-kernel@lists.linaro.org Subject: Re: [PATCH] bpf: convert hashtab lock to raw lock Message-ID: <20151031000356.GA28070@Alexeis-MacBook-Pro.local> References: <1446243386-26582-1-git-send-email-yang.shi@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1446243386-26582-1-git-send-email-yang.shi@linaro.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 30, 2015 at 03:16:26PM -0700, Yang Shi wrote: > When running bpf samples on rt kernel, it reports the below warning: > > BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917 > in_atomic(): 1, irqs_disabled(): 128, pid: 477, name: ping > Preemption disabled at:[] kprobe_perf_func+0x30/0x228 ... > diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c > index 83c209d..972b76b 100644 > --- a/kernel/bpf/hashtab.c > +++ b/kernel/bpf/hashtab.c > @@ -17,7 +17,7 @@ > struct bpf_htab { > struct bpf_map map; > struct hlist_head *buckets; > - spinlock_t lock; > + raw_spinlock_t lock; How do we address such things in general? I bet there are tons of places around the kernel that call spin_lock from atomic. I'd hate to lose the benefits of lockdep of non-raw spin_lock just to make rt happy.