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 X-Spam-Level: X-Spam-Status: No, score=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E60D3C07E97 for ; Sat, 3 Jul 2021 08:23:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B16E561405 for ; Sat, 3 Jul 2021 08:23:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229823AbhGCIO2 (ORCPT ); Sat, 3 Jul 2021 04:14:28 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:46162 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229829AbhGCIO1 (ORCPT ); Sat, 3 Jul 2021 04:14:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1625299913; h=from:from: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=KNgXYIOgFk3/50sq9zIL4S0YcLBbQBv9LP1nNZa2JAA=; b=Is/0ClB5ELfAofWQMDsaxB3Kb/nK36FlRH+ZEQksYtN1iYzZEhCa91txECZEvXPM/BYrgC 77wawFIYhKYRuu9/tFxSCaIW69s+HvY1Q4KSQco49rFgyXD1HljYwNbw9jhnMGkauVjN08 s5RuufRHWPytaeGyAD4/TG58VzTWu2w= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-583-TkOQNl0XNyS-NwD3eXo8NQ-1; Sat, 03 Jul 2021 04:11:51 -0400 X-MC-Unique: TkOQNl0XNyS-NwD3eXo8NQ-1 Received: by mail-wm1-f69.google.com with SMTP id j38-20020a05600c1c26b02901dbf7d18ff8so7477431wms.8 for ; Sat, 03 Jul 2021 01:11:51 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=KNgXYIOgFk3/50sq9zIL4S0YcLBbQBv9LP1nNZa2JAA=; b=NUUEFcVBQgo2/kDkB5GVFYdFbS5iOc2SjO3BBpSZPqXsyaGo6irHofeINhijVa68dg /Fw6ECqxG1rt1dKU+aiW4ExFJbGTCysIka8HgygHBO7nC+joMlsB5Vs0OjaEhQVOrLj5 CQjK3Td7EC2HcxLPbqcziVvJ7gY7UT/JTneyTP74a/hbx8u9ic0SXCMMREakojNFEa8S ErV2z2iwqneu8LtEo5e+bsWBJitJTbsYXGyOILxkgUYz0AWokUo18Y1T+7ypHlclG1rh X9V0ufJvmaFGlbydQwEd9VNmH50urSuIb6unW2c2EU+D1+YB9UQbG2dAjFm8/xYWbbMN 6Law== X-Gm-Message-State: AOAM533lWzWp5ADxKTxnZwLxjnEDuHLavncICUzfRwWU+u5ZsWUpeC64 ghNqgWToMujmIXnZbwQ0b5OQfUYVdi9d6dYXTALgE1pnAMMmPz2Xcu+V+0gcay5823f2S62I0QI 4Bx45tEsp94UrUcrTQw4nOcCu X-Received: by 2002:a05:600c:296:: with SMTP id 22mr3824989wmk.17.1625299910445; Sat, 03 Jul 2021 01:11:50 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwK/iU/CBYEp+7S7mKEGeGippXEk01Zz5EGl2SiAx3okylS3s7KpViTuEX44OaCNPVpb3WcZg== X-Received: by 2002:a05:600c:296:: with SMTP id 22mr3824967wmk.17.1625299910246; Sat, 03 Jul 2021 01:11:50 -0700 (PDT) Received: from redhat.com ([2.55.4.39]) by smtp.gmail.com with ESMTPSA id j37sm2822258wms.37.2021.07.03.01.11.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 03 Jul 2021 01:11:48 -0700 (PDT) Date: Sat, 3 Jul 2021 04:11:45 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: Gautam Dawar , martinh@xilinx.com, hanand@xilinx.com, gdawar@xilinx.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] vhost-vdpa: log warning message if vhost_vdpa_remove gets blocked Message-ID: <20210703041124-mutt-send-email-mst@kernel.org> References: <20210606132909.177640-1-gdawar.xilinx@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 15, 2021 at 10:33:22PM +0800, Jason Wang wrote: > > 在 2021/6/6 下午9:29, Gautam Dawar 写道: > > From: Gautam Dawar > > > > If some module invokes vdpa_device_unregister (usually in the module > > unload function) when the userspace app (eg. QEMU) which had opened > > the vhost-vdpa character device is still running, vhost_vdpa_remove() > > function will block indefinitely in call to wait_for_completion(). > > > > This causes the vdpa_device_unregister caller to hang and with a > > usual side-effect of rmmod command not returning when this call > > is in the module_exit function. > > > > This patch converts the wait_for_completion call to its timeout based > > counterpart (wait_for_completion_timeout) and also adds a warning > > message to alert the user/administrator about this hang situation. > > > > To eventually fix this problem, a mechanism will be required to let > > vhost-vdpa module inform the userspace of this situation and > > userspace will close the descriptor of vhost-vdpa char device. > > This will enable vhost-vdpa to continue with graceful clean-up. > > > > Signed-off-by: Gautam Dawar > > --- > > drivers/vhost/vdpa.c | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > > index bfa4c6ef554e..572b64d09b06 100644 > > --- a/drivers/vhost/vdpa.c > > +++ b/drivers/vhost/vdpa.c > > @@ -1091,7 +1091,11 @@ static void vhost_vdpa_remove(struct vdpa_device *vdpa) > > opened = atomic_cmpxchg(&v->opened, 0, 1); > > if (!opened) > > break; > > - wait_for_completion(&v->completion); > > + wait_for_completion_timeout(&v->completion, > > + msecs_to_jiffies(1000)); > > + dev_warn_ratelimited(&v->dev, > > + "%s waiting for /dev/%s to be closed\n", > > + __func__, dev_name(&v->dev)); Can fill up the kernel log in this case ... dev_warn_once seems more appropriate. > > } while (1); > > put_device(&v->dev); > > > Acked-by: Jason Wang > 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 X-Spam-Level: X-Spam-Status: No, score=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6A308C07E97 for ; Sat, 3 Jul 2021 08:12:20 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0D30A61421 for ; 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Tsirkin" To: Jason Wang Subject: Re: [PATCH] vhost-vdpa: log warning message if vhost_vdpa_remove gets blocked Message-ID: <20210703041124-mutt-send-email-mst@kernel.org> References: <20210606132909.177640-1-gdawar.xilinx@gmail.com> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Cc: kvm@vger.kernel.org, netdev@vger.kernel.org, Gautam Dawar , linux-kernel@vger.kernel.org, gdawar@xilinx.com, virtualization@lists.linux-foundation.org, martinh@xilinx.com, hanand@xilinx.com X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" T24gVHVlLCBKdW4gMTUsIDIwMjEgYXQgMTA6MzM6MjJQTSArMDgwMCwgSmFzb24gV2FuZyB3cm90 ZToKPiAKPiDlnKggMjAyMS82LzYg5LiL5Y2IOToyOSwgR2F1dGFtIERhd2FyIOWGmemBkzoKPiA+ IEZyb206IEdhdXRhbSBEYXdhciA8Z2Rhd2FyQHhpbGlueC5jb20+Cj4gPiAKPiA+IElmIHNvbWUg bW9kdWxlIGludm9rZXMgdmRwYV9kZXZpY2VfdW5yZWdpc3RlciAodXN1YWxseSBpbiB0aGUgbW9k dWxlCj4gPiB1bmxvYWQgZnVuY3Rpb24pIHdoZW4gdGhlIHVzZXJzcGFjZSBhcHAgKGVnLiBRRU1V KSB3aGljaCBoYWQgb3BlbmVkCj4gPiB0aGUgdmhvc3QtdmRwYSBjaGFyYWN0ZXIgZGV2aWNlIGlz IHN0aWxsIHJ1bm5pbmcsIHZob3N0X3ZkcGFfcmVtb3ZlKCkKPiA+IGZ1bmN0aW9uIHdpbGwgYmxv Y2sgaW5kZWZpbml0ZWx5IGluIGNhbGwgdG8gd2FpdF9mb3JfY29tcGxldGlvbigpLgo+ID4gCj4g PiBUaGlzIGNhdXNlcyB0aGUgdmRwYV9kZXZpY2VfdW5yZWdpc3RlciBjYWxsZXIgdG8gaGFuZyBh bmQgd2l0aCBhCj4gPiB1c3VhbCBzaWRlLWVmZmVjdCBvZiBybW1vZCBjb21tYW5kIG5vdCByZXR1 cm5pbmcgd2hlbiB0aGlzIGNhbGwKPiA+IGlzIGluIHRoZSBtb2R1bGVfZXhpdCBmdW5jdGlvbi4K PiA+IAo+ID4gVGhpcyBwYXRjaCBjb252ZXJ0cyB0aGUgd2FpdF9mb3JfY29tcGxldGlvbiBjYWxs IHRvIGl0cyB0aW1lb3V0IGJhc2VkCj4gPiBjb3VudGVycGFydCAod2FpdF9mb3JfY29tcGxldGlv bl90aW1lb3V0KSBhbmQgYWxzbyBhZGRzIGEgd2FybmluZwo+ID4gbWVzc2FnZSB0byBhbGVydCB0 aGUgdXNlci9hZG1pbmlzdHJhdG9yIGFib3V0IHRoaXMgaGFuZyBzaXR1YXRpb24uCj4gPiAKPiA+ IFRvIGV2ZW50dWFsbHkgZml4IHRoaXMgcHJvYmxlbSwgYSBtZWNoYW5pc20gd2lsbCBiZSByZXF1 aXJlZCB0byBsZXQKPiA+IHZob3N0LXZkcGEgbW9kdWxlIGluZm9ybSB0aGUgdXNlcnNwYWNlIG9m IHRoaXMgc2l0dWF0aW9uIGFuZAo+ID4gdXNlcnNwYWNlIHdpbGwgY2xvc2UgdGhlIGRlc2NyaXB0 b3Igb2Ygdmhvc3QtdmRwYSBjaGFyIGRldmljZS4KPiA+IFRoaXMgd2lsbCBlbmFibGUgdmhvc3Qt dmRwYSB0byBjb250aW51ZSB3aXRoIGdyYWNlZnVsIGNsZWFuLXVwLgo+ID4gCj4gPiBTaWduZWQt b2ZmLWJ5OiBHYXV0YW0gRGF3YXIgPGdkYXdhckB4aWxpbnguY29tPgo+ID4gLS0tCj4gPiAgIGRy aXZlcnMvdmhvc3QvdmRwYS5jIHwgNiArKysrKy0KPiA+ICAgMSBmaWxlIGNoYW5nZWQsIDUgaW5z ZXJ0aW9ucygrKSwgMSBkZWxldGlvbigtKQo+ID4gCj4gPiBkaWZmIC0tZ2l0IGEvZHJpdmVycy92 aG9zdC92ZHBhLmMgYi9kcml2ZXJzL3Zob3N0L3ZkcGEuYwo+ID4gaW5kZXggYmZhNGM2ZWY1NTRl Li41NzJiNjRkMDliMDYgMTAwNjQ0Cj4gPiAtLS0gYS9kcml2ZXJzL3Zob3N0L3ZkcGEuYwo+ID4g KysrIGIvZHJpdmVycy92aG9zdC92ZHBhLmMKPiA+IEBAIC0xMDkxLDcgKzEwOTEsMTEgQEAgc3Rh dGljIHZvaWQgdmhvc3RfdmRwYV9yZW1vdmUoc3RydWN0IHZkcGFfZGV2aWNlICp2ZHBhKQo+ID4g ICAJCW9wZW5lZCA9IGF0b21pY19jbXB4Y2hnKCZ2LT5vcGVuZWQsIDAsIDEpOwo+ID4gICAJCWlm ICghb3BlbmVkKQo+ID4gICAJCQlicmVhazsKPiA+IC0JCXdhaXRfZm9yX2NvbXBsZXRpb24oJnYt PmNvbXBsZXRpb24pOwo+ID4gKwkJd2FpdF9mb3JfY29tcGxldGlvbl90aW1lb3V0KCZ2LT5jb21w bGV0aW9uLAo+ID4gKwkJCQkJICAgIG1zZWNzX3RvX2ppZmZpZXMoMTAwMCkpOwo+ID4gKwkJZGV2 X3dhcm5fcmF0ZWxpbWl0ZWQoJnYtPmRldiwKPiA+ICsJCQkJICAgICAiJXMgd2FpdGluZyBmb3Ig L2Rldi8lcyB0byBiZSBjbG9zZWRcbiIsCj4gPiArCQkJCSAgICAgX19mdW5jX18sIGRldl9uYW1l KCZ2LT5kZXYpKTsKCkNhbiBmaWxsIHVwIHRoZSBrZXJuZWwgbG9nIGluIHRoaXMgY2FzZSAuLi4g ZGV2X3dhcm5fb25jZSBzZWVtcyBtb3JlCmFwcHJvcHJpYXRlLgoKPiA+ICAgCX0gd2hpbGUgKDEp Owo+ID4gICAJcHV0X2RldmljZSgmdi0+ZGV2KTsKPiAKPiAKPiBBY2tlZC1ieTogSmFzb24gV2Fu ZyA8amFzb3dhbmdAcmVkaGF0LmNvbT4KPiAKCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fClZpcnR1YWxpemF0aW9uIG1haWxpbmcgbGlzdApWaXJ0dWFsaXph dGlvbkBsaXN0cy5saW51eC1mb3VuZGF0aW9uLm9yZwpodHRwczovL2xpc3RzLmxpbnV4Zm91bmRh dGlvbi5vcmcvbWFpbG1hbi9saXN0aW5mby92aXJ0dWFsaXphdGlvbg==