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 E2596C2D0CD for ; Mon, 19 May 2025 10:52:33 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uGy6b-0005T6-Sj; Mon, 19 May 2025 06:52:25 -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 1uGy6Z-0005Sp-SA for qemu-devel@nongnu.org; Mon, 19 May 2025 06:52:23 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uGy6Y-0001cu-0Y for qemu-devel@nongnu.org; Mon, 19 May 2025 06:52:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1747651940; 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=YF2vWK9Q4r4bHptI7XUcNCW5CxVm7CrKm2zfJGYBN7w=; b=J+S1N+ciVlK3pjD6YMYzyzTuJvn6a5Y4UAlDcWpqSw5+eWQoFMgybhUGE/CUKBJy6Gznx4 fb72w4a1jpY7uUPlCI2cXM+jkP+cNVnWghQXWevYDLdoB2uQXILzFUuhwbrJUD26dmZLku Hd2ntYUZy3uui2ylu6LohMmWc1eu4LQ= Received: from mx-prod-mc-04.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-228-br6rnCesPkyIbL9kXw6O3w-1; Mon, 19 May 2025 06:52:18 -0400 X-MC-Unique: br6rnCesPkyIbL9kXw6O3w-1 X-Mimecast-MFC-AGG-ID: br6rnCesPkyIbL9kXw6O3w_1747651938 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D68871955DAB; Mon, 19 May 2025 10:52:17 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.50]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 682671800268; Mon, 19 May 2025 10:52:16 +0000 (UTC) Date: Mon, 19 May 2025 11:52:12 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Fabiano Rosas Cc: qemu-devel@nongnu.org, marcandre.lureau@redhat.com, pbonzini@redhat.com Subject: Re: [PATCH 2/4] chardev: Don't attempt to unregister yank function more than once Message-ID: References: <20250515222014.4161-1-farosas@suse.de> <20250515222014.4161-3-farosas@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250515222014.4161-3-farosas@suse.de> User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.13, 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=-1, RCVD_IN_MSPIKE_WL=-0.01, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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, May 15, 2025 at 07:20:12PM -0300, Fabiano Rosas wrote: > tcp_chr_free_connection() can be called multiple times in succession, > in which case the yank function will get as argument a NULL s->sioc > that has been cleared by the previous tcp_chr_free_connection() call. > > This leads to an abort() at yank_unregister_function(). > > #0 __GI_raise (sig=6) at ../sysdeps/unix/sysv/linux/raise.c:51 > #1 __GI_abort () at abort.c:79 > #2 qtest_check_status (s=0x513000005600) at ../tests/qtest/libqtest.c:209 > #3 qtest_wait_qemu (s=0x513000005600) at ../tests/qtest/libqtest.c:273 > #4 qtest_kill_qemu (s=0x513000005600) at ../tests/qtest/libqtest.c:285 > #5 kill_qemu_hook_func (s=0x513000005600) at ../tests/qtest/libqtest.c:294 > #6 g_hook_list_invoke (hook_list=0x55ea9cc750c0 , may_recurse=0) at ../glib/ghook.c:534 > #7 sigabrt_handler (signo=6) at ../tests/qtest/libqtest.c:299 > #8 > #9 __GI_raise (sig=6) at ../sysdeps/unix/sysv/linux/raise.c:51 > #10 __GI_abort () at abort.c:79 > #11 yank_unregister_function (instance=0x7fb26f2ea9a0, > func=0x55ea9bcc0a10 , opaque=0x0) at > ../util/yank.c:151 > #12 tcp_chr_free_connection (chr=0x51300000ffc0) at ../chardev/char-socket.c:385 > #13 tcp_chr_disconnect_locked (chr=0x51300000ffc0) at ../chardev/char-socket.c:477 > #14 tcp_chr_disconnect (chr=0x51300000ffc0) at ../chardev/char-socket.c:495 > #15 tcp_chr_hup (channel=0x514000000040, cond=G_IO_HUP, opaque=0x51300000ffc0) at ../chardev/char-socket.c:536 > #16 qio_channel_fd_source_dispatch (source=0x50c0000b5fc0, callback=0x55ea9bcd6770 , > user_data=0x51300000ffc0) at ../io/channel-watch.c:84 > #17 g_main_dispatch (context=0x50f000000040) at ../glib/gmain.c:3381 > #18 g_main_context_dispatch (context=context@entry=0x50f000000040) at ../glib/gmain.c:4099 > #19 g_main_context_iterate (context=0x50f000000040, block=block@entry=1, dispatch=dispatch@entry=1, > self=) at ../glib/gmain.c:4175 > #20 g_main_loop_run (loop=0x502000055690) at ../glib/gmain.c:4373 > > Commit ebae6477dc ("chardev: check if the chardev is registered for > yanking") seems to have encountered a similar issue, but checking > s->registered_yank is not a complete solution because that flag > pertains to the yank instance, not to each individual function. > > Skip the yank_unregister_function() in case s->sioc is already NULL, > which indicates the last yank function was already removed. > > Signed-off-by: Fabiano Rosas > --- > Can tcp_chr_free_connection() race with itself? I'm assuming no. > > Could we just make yank_unregister_instance() remove all yank > functions at once? Those asserts/abort in the yank code are a bit > masochistic. > --- > chardev/char-socket.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) Reviewed-by: Daniel P. Berrangé 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 :|