From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f71.google.com (mail-it0-f71.google.com [209.85.214.71]) by kanga.kvack.org (Postfix) with ESMTP id E0D8D6B0033 for ; Thu, 12 Jan 2017 19:18:39 -0500 (EST) Received: by mail-it0-f71.google.com with SMTP id d9so40838758itc.4 for ; Thu, 12 Jan 2017 16:18:39 -0800 (PST) Received: from lgeamrelo12.lge.com (LGEAMRELO12.lge.com. [156.147.23.52]) by mx.google.com with ESMTP id f83si2639573pfd.13.2017.01.12.16.18.38 for ; Thu, 12 Jan 2017 16:18:39 -0800 (PST) Date: Fri, 13 Jan 2017 09:18:36 +0900 From: Byungchul Park Subject: Re: [PATCH v4 06/15] lockdep: Make save_trace can skip stack tracing of the current Message-ID: <20170113001835.GA3326@X58A-UD3R> References: <1481260331-360-1-git-send-email-byungchul.park@lge.com> <1481260331-360-7-git-send-email-byungchul.park@lge.com> <20170112163757.GC3144@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170112163757.GC3144@twins.programming.kicks-ass.net> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: mingo@kernel.org, tglx@linutronix.de, walken@google.com, boqun.feng@gmail.com, kirill@shutemov.name, linux-kernel@vger.kernel.org, linux-mm@kvack.org, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, npiggin@gmail.com On Thu, Jan 12, 2017 at 05:37:57PM +0100, Peter Zijlstra wrote: > On Fri, Dec 09, 2016 at 02:12:02PM +0900, Byungchul Park wrote: > > Currently, save_trace() always performs save_stack_trace() for the > > current. However, crossrelease needs to use stack trace data of another > > context instead of the current. So add a parameter for skipping stack > > tracing of the current and make it use trace data, which is already > > saved by crossrelease framework. > > > > Signed-off-by: Byungchul Park > > --- > > kernel/locking/lockdep.c | 33 ++++++++++++++++++++------------- > > 1 file changed, 20 insertions(+), 13 deletions(-) > > > > diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c > > index 3eaa11c..11580ec 100644 > > --- a/kernel/locking/lockdep.c > > +++ b/kernel/locking/lockdep.c > > @@ -387,15 +387,22 @@ static void print_lockdep_off(const char *bug_msg) > > #endif > > } > > > > -static int save_trace(struct stack_trace *trace) > > +static int save_trace(struct stack_trace *trace, int skip_tracing) > > { > > - trace->nr_entries = 0; > > - trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; > > - trace->entries = stack_trace + nr_stack_trace_entries; > > + unsigned int nr_avail = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; > > > > - trace->skip = 3; > > - > > - save_stack_trace(trace); > > + if (skip_tracing) { > > + trace->nr_entries = min(trace->nr_entries, nr_avail); > > + memcpy(stack_trace + nr_stack_trace_entries, trace->entries, > > + trace->nr_entries * sizeof(trace->entries[0])); > > + trace->entries = stack_trace + nr_stack_trace_entries; > > + } else { > > + trace->nr_entries = 0; > > + trace->max_entries = nr_avail; > > + trace->entries = stack_trace + nr_stack_trace_entries; > > + trace->skip = 3; > > + save_stack_trace(trace); > > + } > > > > /* > > * Some daft arches put -1 at the end to indicate its a full trace. > > That's pretty nasty semantics.. so when skip_tracing it modifies trace > in-place. I agree. Let me think more and enhance it. Thank you, Byungchul -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org