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[86.27.177.88]) by smtp.gmail.com with ESMTPSA id bi21-20020a05600c3d9500b003814de297fcsm9093215wmb.16.2022.03.03.11.38.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Mar 2022 11:38:28 -0800 (PST) Date: Thu, 3 Mar 2022 19:38:24 +0000 From: Lee Jones To: Leon Romanovsky Subject: Re: [PATCH 1/1] vhost: Provide a kernel warning if mutex is held whilst clean-up in progress Message-ID: References: <20220303151929.2505822-1-lee.jones@linaro.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Cc: kvm@vger.kernel.org, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org 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" T24gVGh1LCAwMyBNYXIgMjAyMiwgTGVvbiBSb21hbm92c2t5IHdyb3RlOgoKPiBPbiBUaHUsIE1h ciAwMywgMjAyMiBhdCAwMzoxOToyOVBNICswMDAwLCBMZWUgSm9uZXMgd3JvdGU6Cj4gPiBBbGwg d29ya2Vycy91c2VycyBzaG91bGQgYmUgaGFsdGVkIGJlZm9yZSBhbnkgY2xlYW4tdXAgc2hvdWxk IHRha2UgcGxhY2UuCj4gPiAKPiA+IFN1Z2dlc3RlZC1ieTogIE1pY2hhZWwgUy4gVHNpcmtpbiA8 bXN0QHJlZGhhdC5jb20+Cj4gPiBTaWduZWQtb2ZmLWJ5OiBMZWUgSm9uZXMgPGxlZS5qb25lc0Bs aW5hcm8ub3JnPgo+ID4gLS0tCj4gPiAgZHJpdmVycy92aG9zdC92aG9zdC5jIHwgMyArKysKPiA+ ICAxIGZpbGUgY2hhbmdlZCwgMyBpbnNlcnRpb25zKCspCj4gPiAKPiA+IGRpZmYgLS1naXQgYS9k cml2ZXJzL3Zob3N0L3Zob3N0LmMgYi9kcml2ZXJzL3Zob3N0L3Zob3N0LmMKPiA+IGluZGV4IGJi YWZmNmE1ZTIxYjguLmQ5MzVkMjUwNjk2M2YgMTAwNjQ0Cj4gPiAtLS0gYS9kcml2ZXJzL3Zob3N0 L3Zob3N0LmMKPiA+ICsrKyBiL2RyaXZlcnMvdmhvc3Qvdmhvc3QuYwo+ID4gQEAgLTY5Myw2ICs2 OTMsOSBAQCB2b2lkIHZob3N0X2Rldl9jbGVhbnVwKHN0cnVjdCB2aG9zdF9kZXYgKmRldikKPiA+ ICAJaW50IGk7Cj4gPiAgCj4gPiAgCWZvciAoaSA9IDA7IGkgPCBkZXYtPm52cXM7ICsraSkgewo+ ID4gKwkJLyogSWRlYWxseSBhbGwgd29ya2VycyBzaG91bGQgYmUgc3RvcHBlZCBwcmlvciB0byBj bGVhbi11cCAqLwo+ID4gKwkJV0FSTl9PTihtdXRleF9pc19sb2NrZWQoJmRldi0+dnFzW2ldLT5t dXRleCkpOwo+ID4gKwo+ID4gIAkJbXV0ZXhfbG9jaygmZGV2LT52cXNbaV0tPm11dGV4KTsKPiAK PiBJIGtub3cgbm90aGluZyBhYm91dCB2aG9zdCwgYnV0IHRoaXMgY29uc3RydWN0aW9uIGFuZCBw YXRjaCBsb29rcwo+IHN0cmFuZ2UgdG8gbWUuCj4gCj4gSWYgYWxsIHdvcmtlcnMgd2VyZSBzdG9w cGVkLCB5b3Ugd29uJ3QgbmVlZCBtdXRleF9sb2NrKCkuIFRoZSBtdXRleF9sb2NrCj4gaGVyZSBz dWdnZXN0cyB0byBtZSB0aGF0IHdvcmtlcnMgY2FuIHN0aWxsIHJ1biBoZXJlLgoKVGhlIHN1Z2dl c3Rpb24gZm9yIHRoaXMgcGF0Y2ggY2FtZSBmcm9tIHRoZSBtYWludGFpbmVyLgoKUGxlYXNlIHNl ZSB0aGUgY29udmVyc2F0aW9uIGhlcmU6CgpodHRwczovL2xvcmUua2VybmVsLm9yZy9hbGwvMjAy MjAzMDIwODIwMjEtbXV0dC1zZW5kLWVtYWlsLW1zdEBrZXJuZWwub3JnLwoKLS0gCkxlZSBKb25l cyBb5p2O55C85pavXQpQcmluY2lwYWwgVGVjaG5pY2FsIExlYWQgLSBEZXZlbG9wZXIgU2Vydmlj ZXMKTGluYXJvLm9yZyDilIIgT3BlbiBzb3VyY2Ugc29mdHdhcmUgZm9yIEFybSBTb0NzCkZvbGxv dyBMaW5hcm86IEZhY2Vib29rIHwgVHdpdHRlciB8IEJsb2cKX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX18KVmlydHVhbGl6YXRpb24gbWFpbGluZyBsaXN0ClZp cnR1YWxpemF0aW9uQGxpc3RzLmxpbnV4LWZvdW5kYXRpb24ub3JnCmh0dHBzOi8vbGlzdHMubGlu dXhmb3VuZGF0aW9uLm9yZy9tYWlsbWFuL2xpc3RpbmZvL3ZpcnR1YWxpemF0aW9u 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BFA75C4332F for ; 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[86.27.177.88]) by smtp.gmail.com with ESMTPSA id bi21-20020a05600c3d9500b003814de297fcsm9093215wmb.16.2022.03.03.11.38.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Mar 2022 11:38:28 -0800 (PST) Date: Thu, 3 Mar 2022 19:38:24 +0000 From: Lee Jones To: Leon Romanovsky Cc: mst@redhat.com, jasowang@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: Re: [PATCH 1/1] vhost: Provide a kernel warning if mutex is held whilst clean-up in progress Message-ID: References: <20220303151929.2505822-1-lee.jones@linaro.org> 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: kvm@vger.kernel.org On Thu, 03 Mar 2022, Leon Romanovsky wrote: > On Thu, Mar 03, 2022 at 03:19:29PM +0000, Lee Jones wrote: > > All workers/users should be halted before any clean-up should take place. > > > > Suggested-by: Michael S. Tsirkin > > Signed-off-by: Lee Jones > > --- > > drivers/vhost/vhost.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > > index bbaff6a5e21b8..d935d2506963f 100644 > > --- a/drivers/vhost/vhost.c > > +++ b/drivers/vhost/vhost.c > > @@ -693,6 +693,9 @@ void vhost_dev_cleanup(struct vhost_dev *dev) > > int i; > > > > for (i = 0; i < dev->nvqs; ++i) { > > + /* Ideally all workers should be stopped prior to clean-up */ > > + WARN_ON(mutex_is_locked(&dev->vqs[i]->mutex)); > > + > > mutex_lock(&dev->vqs[i]->mutex); > > I know nothing about vhost, but this construction and patch looks > strange to me. > > If all workers were stopped, you won't need mutex_lock(). The mutex_lock > here suggests to me that workers can still run here. The suggestion for this patch came from the maintainer. Please see the conversation here: https://lore.kernel.org/all/20220302082021-mutt-send-email-mst@kernel.org/ -- Lee Jones [李琼斯] Principal Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog