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Mon, 12 Apr 2021 15:08:22 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxQq02VEH0x+yR4nCVseGnJU8z9TNWYz+YkkYnKTZ8stWzkVM0s8+ImnNF6USPPWg4NmHoYgQ== X-Received: by 2002:a05:600c:329c:: with SMTP id t28mr1073698wmp.74.1618265301866; Mon, 12 Apr 2021 15:08:21 -0700 (PDT) Received: from redhat.com ([2a10:8006:2281:0:1994:c627:9eac:1825]) by smtp.gmail.com with ESMTPSA id v7sm17127237wrs.2.2021.04.12.15.08.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 12 Apr 2021 15:08:19 -0700 (PDT) Date: Mon, 12 Apr 2021 18:08:16 -0400 From: "Michael S. Tsirkin" To: Wei Wang Subject: Re: [PATCH net] virtio-net: suppress bad irq warning for tx napi Message-ID: <20210412180353-mutt-send-email-mst@kernel.org> References: <20210129002136.70865-1-weiwan@google.com> MIME-Version: 1.0 In-Reply-To: <20210129002136.70865-1-weiwan@google.com> Ccc: Eugenio Perez Martin 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: netdev@vger.kernel.org, Willem de Bruijn , virtualization@lists.linux-foundation.org, David Miller , Jakub Kicinski 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="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" OK I started looking at this again. My idea is simple. A. disable callbacks before we try to drain skbs B. actually do disable callbacks even with event idx To make B not regress, we need to C. detect the common case of disable after event triggering and skip the write then. I added a new event_triggered flag for that. Completely untested - but then I could not see the warnings either. Would be very much interested to know whether this patch helps resolve the sruprious interrupt problem at all ... Signed-off-by: Michael S. Tsirkin diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 82e520d2cb12..a91a2d6d1ee3 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1429,6 +1429,7 @@ static void virtnet_poll_cleantx(struct receive_queue *rq) return; if (__netif_tx_trylock(txq)) { + virtqueue_disable_cb(vq); free_old_xmit_skbs(sq, true); __netif_tx_unlock(txq); } diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 71e16b53e9c1..213bfe8b6051 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -113,6 +113,9 @@ struct vring_virtqueue { /* Last used index we've seen. */ u16 last_used_idx; + /* Hint for event idx: already triggered no need to disable. */ + bool event_triggered; + union { /* Available for split ring */ struct { @@ -739,7 +742,10 @@ static void virtqueue_disable_cb_split(struct virtqueue *_vq) if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) { vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT; - if (!vq->event) + if (vq->event) + /* TODO: this is a hack. Figure out a cleaner value to write. */ + vring_used_event(&vq->split.vring) = 0x0; + else vq->split.vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->split.avail_flags_shadow); @@ -1605,6 +1611,7 @@ static struct virtqueue *vring_create_virtqueue_packed( vq->weak_barriers = weak_barriers; vq->broken = false; vq->last_used_idx = 0; + vq->event_triggered = false; vq->num_added = 0; vq->packed_ring = true; vq->use_dma_api = vring_use_dma_api(vdev); @@ -1919,6 +1926,14 @@ void virtqueue_disable_cb(struct virtqueue *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); + /* If device triggered an event already it won't trigger one again: + * no need to disable. + */ + if (vq->event_triggered) { + vq->event_triggered = false; + return; + } + if (vq->packed_ring) virtqueue_disable_cb_packed(_vq); else @@ -2044,6 +2059,10 @@ irqreturn_t vring_interrupt(int irq, void *_vq) if (unlikely(vq->broken)) return IRQ_HANDLED; + /* Just a hint for performance: so it's ok that this can be racy! */ + if (vq->event) + vq->event_triggered = true; + pr_debug("virtqueue callback for %p (%p)\n", vq, vq->vq.callback); if (vq->vq.callback) vq->vq.callback(&vq->vq); @@ -2083,6 +2102,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index, vq->weak_barriers = weak_barriers; vq->broken = false; vq->last_used_idx = 0; + vq->event_triggered = false; vq->num_added = 0; vq->use_dma_api = vring_use_dma_api(vdev); #ifdef DEBUG _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization