From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx4/fuNOF9ARM6k6ZWRp/Pw1rVYi7u5nnAJhruPa6ZNLz9qFfXp5EYb3FkHN7lieT3vAXuQuH ARC-Seal: i=1; a=rsa-sha256; t=1524406286; cv=none; d=google.com; s=arc-20160816; b=hhcJlvsbEfQBYdt6R60pbSM0HusFM+CrlkWVHupj0xAEAOcfJEVkMdvA/LNW/jjVRE GWvB/zC2eaISwpKivM89J4nFmTprJmh6ecodxFzBVGhaW60o+AA13rGSwx9QP/Imkl/E br5fmHBgP2zDdVJWwptmRjLdbvh+KVbP+QRxLgUTzK32ugfswNqEQLvTgLF689viTNLo lpHjoOd+RDuuR0Tl/iGKsRSpM9qIfQkL8sVV9fyXah87K1okK0YEQXyhBNB71QkYBJEt lKbJFQqMZtUJE6n8Ceusj7Sozu8BAKZYxYkJll8uLY2enLo3FGucDgzBLJLW9r9vBggl JTiA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=1ocXqAOC6GYXRP0dOul5+a+5P22Aw15Oa/GWm3ithxY=; b=t48ITfnlvHqr2v6FthfuE2lgvgzn2hnjwKoS6Dyl/z2cPEZcVsSDM3JcjC+8mJLD5x cJyno0dkyuBSWh9WR5r2E9REKfyr0GY5Vc4e460HcNPNJ3YhOJ5avdS35/UZO8iIkpZD YRSlwYhdpDRguYkuujYBbjlM5kUqAGFxsJM3KaTW1IHQRoSzOTB7WKRCr95z0gvWiHpR RJe/7C83gmngXM5LuLZESouHkxKQ5AfglVIpyWVUEX84GYqsuYjK6mn0v3xZLHt2trDo lNevvHR2ZuJKmX9VriDKnp1reFnde+r6zvPhOJNkNimCf0ed80g4j3NldO4D+4fz0nIS ZuTw== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jason Andryuk , Eduardo Otubo , Boris Ostrovsky , Juergen Gross Subject: [PATCH 4.9 16/95] xen-netfront: Fix hang on device removal Date: Sun, 22 Apr 2018 15:52:45 +0200 Message-Id: <20180422135211.106716057@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180422135210.432103639@linuxfoundation.org> References: <20180422135210.432103639@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1598455501364355262?= X-GMAIL-MSGID: =?utf-8?q?1598455846995064718?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jason Andryuk commit c2d2e6738a209f0f9dffa2dc8e7292fc45360d61 upstream. A toolstack may delete the vif frontend and backend xenstore entries while xen-netfront is in the removal code path. In that case, the checks for xenbus_read_driver_state would return XenbusStateUnknown, and xennet_remove would hang indefinitely. This hang prevents system shutdown. xennet_remove must be able to handle XenbusStateUnknown, and netback_changed must also wake up the wake_queue for that state as well. Fixes: 5b5971df3bc2 ("xen-netfront: remove warning when unloading module") Signed-off-by: Jason Andryuk Cc: Eduardo Otubo Reviewed-by: Boris Ostrovsky Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman --- drivers/net/xen-netfront.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -2038,7 +2038,10 @@ static void netback_changed(struct xenbu case XenbusStateInitialised: case XenbusStateReconfiguring: case XenbusStateReconfigured: + break; + case XenbusStateUnknown: + wake_up_all(&module_unload_q); break; case XenbusStateInitWait: @@ -2169,7 +2172,9 @@ static int xennet_remove(struct xenbus_d xenbus_switch_state(dev, XenbusStateClosing); wait_event(module_unload_q, xenbus_read_driver_state(dev->otherend) == - XenbusStateClosing); + XenbusStateClosing || + xenbus_read_driver_state(dev->otherend) == + XenbusStateUnknown); xenbus_switch_state(dev, XenbusStateClosed); wait_event(module_unload_q,