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 B5DB9CAC582 for ; Fri, 12 Sep 2025 10:14:13 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ux0jS-0003j1-Po; Fri, 12 Sep 2025 06:10:19 -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 1ux0jQ-0003fN-WE for qemu-devel@nongnu.org; Fri, 12 Sep 2025 06:10:17 -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 1ux0jJ-0002Un-RT for qemu-devel@nongnu.org; Fri, 12 Sep 2025 06:10:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1757671806; 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=UReYHOAkzoHpQtGeGSdr0cEulBvUQbkY/8Z8y5KPB9o=; b=ayJw73o+quAfFG+jK7wz9T+rec9VrlRHD14KtkZSJ70iJ/dbg9QX1uVqIonZ2Rb0sbtTV4 ULAqDdqC8vJbR7nUucPWBofvfT9ZGSCBXrEAjlDmMwZiP98jqNnXO8BUEbX16vRCinntyb z101HJeMzned4wnMF+S0rOvTCq3WBPw= Received: from mx-prod-mc-02.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-153-xR7NyC_gNFqCyNwkVXDgqA-1; Fri, 12 Sep 2025 06:10:03 -0400 X-MC-Unique: xR7NyC_gNFqCyNwkVXDgqA-1 X-Mimecast-MFC-AGG-ID: xR7NyC_gNFqCyNwkVXDgqA_1757671802 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 411111955EA8; Fri, 12 Sep 2025 10:10:02 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.154]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3CE3519560B1; Fri, 12 Sep 2025 10:10:00 +0000 (UTC) Date: Fri, 12 Sep 2025 11:09:56 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Markus Armbruster Cc: qemu-devel@nongnu.org, odaki@rsg.ci.i.u-tokyo.ac.jp, marcandre.lureau@redhat.com Subject: Re: [PATCH 06/12] net/slirp: Clean up error reporting Message-ID: References: <20250808080823.2638861-1-armbru@redhat.com> <20250808080823.2638861-7-armbru@redhat.com> <87348vzwdw.fsf@pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87348vzwdw.fsf@pond.sub.org> User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_PASS=-0.001, T_SPF_HELO_TEMPERROR=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 Tue, Sep 09, 2025 at 01:40:59PM +0200, Markus Armbruster wrote: > Daniel P. Berrangé writes: > > > On Fri, Aug 08, 2025 at 10:08:17AM +0200, Markus Armbruster wrote: > >> net_slirp_register_poll_sock() and net_slirp_unregister_poll_sock() > >> report WSAEventSelect() failure with error_setg(&error_warn, ...). > >> > >> I'm not familiar with liblirp, so I can't say whether the network > > > > ^^^^^^^^^ 'libslirp' > > Will fix, thanks! > > >> backend will work after such a failure. If it doesn't, then this > >> should be an error. If it does, then why bother the user with a > >> warning that isn't actionable, and likely confusing? > >> > >> Regardless of that, error_setg_win32(&error_warn, ...) is undesirable > >> just like error_setg(&error_fatal, ...) and error_setg(&error_abort, > >> ...) are. Replace by warn_report(). > >> > >> Cc: Marc-André Lureau > >> Signed-off-by: Markus Armbruster > >> --- > >> net/slirp.c | 6 ++++-- > >> 1 file changed, 4 insertions(+), 2 deletions(-) > > > > Reviewed-by: Daniel P. Berrangé > > > >> diff --git a/net/slirp.c b/net/slirp.c > >> index 9657e86a84..d75b09f16b 100644 > >> --- a/net/slirp.c > >> +++ b/net/slirp.c > >> @@ -262,7 +262,8 @@ static void net_slirp_register_poll_sock(slirp_os_socket fd, void *opaque) > >> if (WSAEventSelect(fd, event_notifier_get_handle(&ctxt->notifier), > >> FD_READ | FD_ACCEPT | FD_CLOSE | > >> FD_CONNECT | FD_WRITE | FD_OOB) != 0) { > >> - error_setg_win32(&error_warn, WSAGetLastError(), "failed to WSAEventSelect()"); > >> + warn_report("failed to WSAEventSelect(): %s", > >> + g_win32_error_message(WSAGetLastError())); > >> } > >> #endif > > > > IMHO this one ought to be considered fatal. If we can't select the > > right events on the socket, then we're not going to have a good time > > trying to poll on events. The libslirp callback API doesn't allow > > us to return a success/failure code from this function, and IMHO it > > is not appropriate to use error_fatal here because a fault with slirp > > should not take down the whole of QEMU. So warn_report is the least > > worst option I guess. At least it is a hint to the user that all is > > not well - even if they can't action it, it might alert them if they > > see network problems in their guest. > > So, we'd make this an error if we could. But we can't: the function is > a callback that cannot fail, and outright exit(1) is too harsh. > > That leaves silence or warning. Warning is less bad. > > Correct? Yes. > >> @@ -271,7 +272,8 @@ static void net_slirp_unregister_poll_sock(slirp_os_socket fd, void *opaque) > >> { > >> #ifdef WIN32 > >> if (WSAEventSelect(fd, NULL, 0) != 0) { > >> - error_setg_win32(&error_warn, WSAGetLastError(), "failed to WSAEventSelect()"); > >> + warn_report("failed to WSAEventSelect()", > >> + g_win32_error_message(WSAGetLastError())); > >> } > > > > This one is reasonable to treat as non-fatal, since once we've > > unregistered the socket for polling > > Whether clearing the event associated with the socket can fail is > unclear. Whether it should be treated as an error is also unclear. > > If yes, then same argument as for net_slirp_register_poll_sock() above. If the callback allowed returning an error, we probably would return an error, but then I'm confident slirp would do nothing more than print a warning and continue to close the file handle as normal. It doesn't make sense to turn file descriptor cleanup into fatal error. > > If no, silence or warning. Warning is less bad. > > Correct? Yes. 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 :|