From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76174C04EB9 for ; Thu, 6 Dec 2018 08:10:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3652420661 for ; Thu, 6 Dec 2018 08:10:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="dEli7pH+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3652420661 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729306AbeLFIKv (ORCPT ); Thu, 6 Dec 2018 03:10:51 -0500 Received: from merlin.infradead.org ([205.233.59.134]:46310 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728909AbeLFIKr (ORCPT ); Thu, 6 Dec 2018 03:10:47 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=RuSKxDTa8+Z9jYfBiTGZgYMi8wq+m7YLY9Nx1eKCr4c=; b=dEli7pH+L6UYZSWsQ/A/wwWZJ 2Z3Ex8wHFiwUa8NFskQZIVQ/im8Nm+VziwkhK6ZMGpIqvFOP0InxEOI/gzNrS0OZl0K0kUKVL31hZ PRbyzRaNHuVJA0ydqeMtPwlzLs6oKhx9y5cEU5f2K5Zil4w8qpfunwF1gOfiUt0ctYHS7S/qujim4 U2QCZkAkzxlLYa6ewKL4pYw0ZH08MQp8AU+j9PNcGkwsJzNAVKNcBIR3xrSpnenXxSb5hH1OhqOM0 7W2+Dgu8WLYaBgzYlF0YIu7eBg+1i+VQYA8W1ve+1E2SdWVN5a0Cy1+o59AhHZgjr9/93pQHekuRW Szv2MiZ5w==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gUojv-0004tr-Qk; Thu, 06 Dec 2018 08:10:32 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 435B82029F4C1; Thu, 6 Dec 2018 09:10:28 +0100 (CET) Date: Thu, 6 Dec 2018 09:10:28 +0100 From: Peter Zijlstra To: Jiri Olsa Cc: Arnaldo Carvalho de Melo , Steven Rostedt , lkml , Ingo Molnar , Namhyung Kim , Alexander Shishkin , Thomas Gleixner , "Luis Claudio R. Goncalves" , ldv@altlinux.org, esyr@redhat.com, Frederic Weisbecker Subject: Re: [PATCH 1/8] perf: Allow to block process in syscall tracepoints Message-ID: <20181206081028.GE4234@hirez.programming.kicks-ass.net> References: <20181205160509.1168-1-jolsa@kernel.org> <20181205160509.1168-2-jolsa@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181205160509.1168-2-jolsa@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 05, 2018 at 05:05:02PM +0100, Jiri Olsa wrote: > +static void trace_block_syscall(struct pt_regs *regs, bool enter) > +{ > + current->perf_blocked = true; > + > + do { > + schedule_timeout(100 * HZ); > + current->perf_blocked_cnt = 0; > + > + if (enter) { > + /* perf syscalls:* enter */ > + perf_trace_syscall_enter(regs); > + > + /* perf raw_syscalls:* enter */ > + perf_trace_sys_enter(&event_sys_enter, regs, regs->orig_ax); > + } else { > + /* perf syscalls:* enter */ > + perf_trace_syscall_exit(regs); > + > + /* perf raw_syscalls:* enter */ > + perf_trace_sys_exit(&event_sys_exit, regs, regs->ax); > + } > + } while (current->perf_blocked_cnt); > + > + current->perf_blocked = false; > +} I don't understand this.. why are we using schedule_timeout() and all that?