Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756036AbaF3Rvv (ORCPT ); Mon, 30 Jun 2014 13:51:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38049 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753233AbaF3Rvu (ORCPT ); Mon, 30 Jun 2014 13:51:50 -0400 Date: Mon, 30 Jun 2014 19:50:25 +0200 From: Oleg Nesterov To: Srikar Dronamraju Cc: Steven Rostedt , Masami Hiramatsu , Namhyung Kim , Tom Zanussi , "zhangwei(Jovi)" , linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/4] tracing/uprobes: Fix the usage of uprobe_buffer_enable() in probe_event_enable() Message-ID: <20140630175025.GA21918@redhat.com> References: <20140627170116.GA18298@redhat.com> <20140627170146.GA18332@redhat.com> <20140630170409.GD5619@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140630170409.GD5619@linux.vnet.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/30, Srikar Dronamraju wrote: > > > The usage of uprobe_buffer_enable() added by dcad1a20 is very wrong, > > > > 1. uprobe_buffer_enable() and uprobe_buffer_disable() are not balanced, > > _enable() should be called only if !enabled. > > > > 2. If uprobe_buffer_enable() fails probe_event_enable() should clear > > tp.flags and free event_file_link. > > > > 3. If uprobe_register() fails it should do uprobe_buffer_disable(). > > > > Signed-off-by: Oleg Nesterov > > Acked-by: Srikar Dronamraju Thanks! > (one nit .. ) > > > + ret = uprobe_buffer_enable(); > > + if (ret) > > + goto err_flags; > > + > > tu->consumer.filter = filter; > > ret = uprobe_register(tu->inode, tu->offset, &tu->consumer); > > - if (ret) { > > - if (file) { > > - list_del(&link->list); > > - kfree(link); > > - tu->tp.flags &= ~TP_FLAG_TRACE; > > - } else > > - tu->tp.flags &= ~TP_FLAG_PROFILE; > > - } > > + if (ret) > > + goto err_buffer; > > > > + return 0; > > + > > + err_buffer: > > + uprobe_buffer_disable(); > > + > > How about avoiding err_buffer label? > + if (!ret) > + return 0; > > + uprobe_buffer_disable(); > + Well, I do not really mind. But to me it looks more consistent this way, if-something-fail-goto-err_label. IOW, I think that the code should either not use err-labels, or always use them like above. Besides, perhaps we will add "if (file) uprobe_apply()" after _register() to mix perf/ftrace, then we will need to change this "if (!ret)" code again. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/