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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D9812C7EE2E for ; Thu, 29 Aug 2024 07:16:14 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sjZNK-0001rk-0X; Thu, 29 Aug 2024 03:15:22 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sjZN9-0001qY-Dz for qemu-devel@nongnu.org; Thu, 29 Aug 2024 03:15:13 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sjZN7-0007VY-09 for qemu-devel@nongnu.org; Thu, 29 Aug 2024 03:15:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1724915706; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7IBE6IaiAEMRciJWtSMhKOiiBhE1VCTLKX6wFjCaafA=; b=KUwFNRcjuySdI8O0H8RCYzqPYqZqJUNgaRj+oMHbuGZGsT5yYTLD0tLOM3rdpzJlA4UXnp mMBrquU8TQ6H8AU2jyd1BSVeNCppSokP0f8Py0nGvLjF4ItINlva/GAvuyLCqHNM/tF7Xo pcXb1CP24hpsOWSTNg+nGjSR7A46noM= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-355-7NcTPh0lNRuzlXF71RUblQ-1; Thu, 29 Aug 2024 03:15:02 -0400 X-MC-Unique: 7NcTPh0lNRuzlXF71RUblQ-1 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 750E51954B07; Thu, 29 Aug 2024 07:15:01 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.64]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0A35D19560A3; Thu, 29 Aug 2024 07:14:59 +0000 (UTC) Date: Thu, 29 Aug 2024 08:14:56 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Richard Henderson Cc: qemu-devel@nongnu.org, =?utf-8?B?Q2zDqW1lbnQgTMOpZ2Vy?= Subject: Re: [PULL 3/6] qemu/osdep: Split qemu_close_all_open_fd() and add fallback Message-ID: References: <20240805003130.1421051-1-richard.henderson@linaro.org> <20240805003130.1421051-5-richard.henderson@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, Aug 29, 2024 at 08:47:27AM +1000, Richard Henderson wrote: > On 8/28/24 22:48, Daniel P. Berrangé wrote: > > > dir = opendir("/proc/self/fd"); > > > > IIUC from previous threads this is valid on Linux and on Solaris. > > > > On FreeBSD & macOS, you need /dev/fd though. > > Fair, but importantly, it doesn't do anything *incorrect* those systems: it > merely skips this method with ENOENT. > > > > + int open_max = sysconf(_SC_OPEN_MAX), i; > > > + > > > + /* Fallback */ > > > + for (i = 0; i < open_max; i++) { > > > + close(i); > > > + } > > > > I'm told that sysconf(_SC_OPEN_MAX) returns -1 on some versions of > > macOS. "Luckily" since we assigned to 'int' rather than 'unsigned int' > > this will result in us not closing any FDs in this fallback path, > > rather than trying to close several billion FDs (an effective hang). > > Ouch. > > > > > If _SC_OPEN_MAX returns -1, we should fallback to the OPEN_MAX > > constant on macOS (see commit de448e0f26e710e9d2b7fc91393c40ac24b75847 > > which tackled a similar issue wrt getrlimit), and fallback to perhaps > > a hardcoded 1024 on non-macOS. > > I wish the timing on this had been better -- 25 minutes earlier and I would have delayed rc4. > > Since macOS simply doesn't close fds, I'm of a mind to release 9.1.0 without > this, and fix it for 9.1.1. Thoughts? The original net/tap.c code for closing FDs has the same bug, so in that area we do NOT have a regression. The original async teardown code would fail to close FDs as it is looking for close_range or /proc/$PID/fd, and has no sysconf fallback, so again no regression there. IOW, I think this is acceptable to fix in 9.1 stable. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|