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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A02AC77B61 for ; Tue, 25 Apr 2023 01:40:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232896AbjDYBkD (ORCPT ); Mon, 24 Apr 2023 21:40:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230379AbjDYBkC (ORCPT ); Mon, 24 Apr 2023 21:40:02 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC573AF0A; Mon, 24 Apr 2023 18:40:01 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 4641E6203D; Tue, 25 Apr 2023 01:40:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A8E2DC433EF; Tue, 25 Apr 2023 01:39:59 +0000 (UTC) Date: Mon, 24 Apr 2023 21:39:57 -0400 From: Steven Rostedt To: Beau Belgrave Cc: mhiramat@kernel.org, mathieu.desnoyers@efficios.com, dcook@linux.microsoft.com, alanau@linux.microsoft.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] tracing/user_events: Ensure bit is cleared on unregister Message-ID: <20230424213957.55c503c1@rorschach.local.home> In-Reply-To: <20230411211709.15018-3-beaub@linux.microsoft.com> References: <20230411211709.15018-1-beaub@linux.microsoft.com> <20230411211709.15018-3-beaub@linux.microsoft.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org On Tue, 11 Apr 2023 14:17:08 -0700 Beau Belgrave wrote: > +static int user_event_mm_clear_bit(struct user_event_mm *user_mm, > + unsigned long uaddr, unsigned char bit) > +{ > + struct user_event_enabler enabler; > + int result; > + > + memset(&enabler, 0, sizeof(enabler)); > + enabler.addr = uaddr; > + enabler.values = bit; > +retry: > + /* Prevents state changes from racing with new enablers */ > + mutex_lock(&event_mutex); > + > + /* Force the bit to be cleared, since no event is attached */ > + mmap_read_lock(user_mm->mm); > + result = user_event_enabler_write(user_mm, &enabler, false); > + mmap_read_unlock(user_mm->mm); > + > + mutex_unlock(&event_mutex); > + > + if (result) { > + /* Attempt to fault-in and retry if it worked */ > + if (!user_event_mm_fault_in(user_mm, uaddr)) > + goto retry; Without looking into the functions of this call, I wonder if this can get into an infinite loop? -- Steve > + } > + > + return result; > +} > +