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[83.52.55.163]) by smtp.gmail.com with ESMTPSA id f17sm3086742wmq.17.2021.08.26.10.27.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Aug 2021 10:27:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1629998836; 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=u6X8NyK5dk4UMskkp60riuy7ptxhQXw1NrJ4q4sajpM=; b=cVY++T/b6OjvNK10pSxrcasGp9tActIgol8IWAw7iWrHwbDbqtBT/Z8cUo3BQQtjSQTcg3 tFa5c4SRG5EZYbaXp2222THNUQDK67stcI2UwFRPSKsfFNiFKJNp7mmRP4tE5bWkVg44MN eFkc1zsr2DU+MAJfKk+WAMOJolokXF0= X-MC-Unique: Hxqh3FPYM92ozIZomYwlQg-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=u6X8NyK5dk4UMskkp60riuy7ptxhQXw1NrJ4q4sajpM=; b=KvD0BnVeqvUIg63qwXdTEK3L6DCfG2omIzUR6RB3sBWMRbIf5PNW8yf54BjDMfmTbo S1Kfy1iMBTVYzQ+pM3RBpCdVhP9jqdSsRC/qCB81molGDpU2GG26Z2vrTjil8MIH9Q4H on2NqJ4sJOlinVe00+5K0BUjuVkwvsV6krW7XPbeeSa5In8GmDiZAEbftzyFUEGnfqNF LZHPEJg0YmHhJ/BHGZe4iW76VTarYLnqGvgiM2KAEp3aaXDYMgzHj1c0GuIWTL3Q69tB 9alI/quQfsV4rw+hffv0VFTk9h1/ad9YPWqgaNbPSVyljq4nv2gY/Et5D44iAoNYswDb ePrw== X-Gm-Message-State: AOAM532u0DPZT18jyIUWtVwyXSaB1B8mgxalDMObCBvNXX7QYkA8AtJf wbkGM1OihFV5wEa6cPFtTU7VRKKU1pT0m+lcRp5IDJuc0UQsKGTDjr0AzPJaS4/A+aE1kgCxsD1 NgKIpQJdXnDX+EA== X-Received: by 2002:a5d:58c8:: with SMTP id o8mr5506600wrf.361.1629998833962; Thu, 26 Aug 2021 10:27:13 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwErpc98NO68+MUutfIByeCyHkpxiyIPjG2+peayvoErVmjgBGYYUv9Eg0Fzv8rNcdkUG2+LA== X-Received: by 2002:a5d:58c8:: with SMTP id o8mr5506587wrf.361.1629998833828; Thu, 26 Aug 2021 10:27:13 -0700 (PDT) From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= To: qemu-devel@nongnu.org Cc: Jason Wang , Stefan Hajnoczi , Paolo Bonzini , "Michael S. Tsirkin" , Cornelia Huck , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Subject: [RFC PATCH 3/3] hw/virtio: Have virtqueue_get_avail_bytes() pass caches arg to callees Date: Thu, 26 Aug 2021 19:26:58 +0200 Message-Id: <20210826172658.2116840-4-philmd@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210826172658.2116840-1-philmd@redhat.com> References: <20210826172658.2116840-1-philmd@redhat.com> MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=philmd@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1629998838132100001 Both virtqueue_packed_get_avail_bytes() and virtqueue_split_get_avail_bytes() access the region cache, but their caller also does. Simplify by having virtqueue_get_avail_bytes calling both with RCU lock held, and passing the caches as argument. Signed-off-by: Philippe Mathieu-Daud=C3=A9 --- RFC because I'm not sure this is safe enough --- hw/virtio/virtio.c | 29 ++++++++++++----------------- 1 file changed, 12 insertions(+), 17 deletions(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 3a1f6c520cb..8237693a567 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -984,28 +984,23 @@ static int virtqueue_split_read_next_desc(VirtIODevic= e *vdev, VRingDesc *desc, return VIRTQUEUE_READ_DESC_MORE; } =20 +/* Called within rcu_read_lock(). */ static void virtqueue_split_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes, unsigned int *out_byte= s, - unsigned max_in_bytes, unsigned max_out_bytes) + unsigned max_in_bytes, unsigned max_out_bytes, + VRingMemoryRegionCaches *caches) { VirtIODevice *vdev =3D vq->vdev; unsigned int max, idx; unsigned int total_bufs, in_total, out_total; - VRingMemoryRegionCaches *caches; MemoryRegionCache indirect_desc_cache =3D MEMORY_REGION_CACHE_INVALID; int64_t len =3D 0; int rc; =20 - RCU_READ_LOCK_GUARD(); - idx =3D vq->last_avail_idx; total_bufs =3D in_total =3D out_total =3D 0; =20 max =3D vq->vring.num; - caches =3D vring_get_region_caches(vq); - if (!caches) { - goto err; - } =20 while ((rc =3D virtqueue_num_heads(vq, idx)) > 0) { MemoryRegionCache *desc_cache =3D &caches->desc; @@ -1124,32 +1119,28 @@ static int virtqueue_packed_read_next_desc(VirtQueu= e *vq, return VIRTQUEUE_READ_DESC_MORE; } =20 +/* Called within rcu_read_lock(). */ static void virtqueue_packed_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes, unsigned int *out_bytes, unsigned max_in_bytes, - unsigned max_out_bytes) + unsigned max_out_bytes, + VRingMemoryRegionCaches *cach= es) { VirtIODevice *vdev =3D vq->vdev; unsigned int max, idx; unsigned int total_bufs, in_total, out_total; MemoryRegionCache *desc_cache; - VRingMemoryRegionCaches *caches; MemoryRegionCache indirect_desc_cache =3D MEMORY_REGION_CACHE_INVALID; int64_t len =3D 0; VRingPackedDesc desc; bool wrap_counter; =20 - RCU_READ_LOCK_GUARD(); idx =3D vq->last_avail_idx; wrap_counter =3D vq->last_avail_wrap_counter; total_bufs =3D in_total =3D out_total =3D 0; =20 max =3D vq->vring.num; - caches =3D vring_get_region_caches(vq); - if (!caches) { - goto err; - } =20 for (;;) { unsigned int num_bufs =3D total_bufs; @@ -1250,6 +1241,8 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigne= d int *in_bytes, uint16_t desc_size; VRingMemoryRegionCaches *caches; =20 + RCU_READ_LOCK_GUARD(); + if (unlikely(!vq->vring.desc)) { goto err; } @@ -1268,10 +1261,12 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsig= ned int *in_bytes, =20 if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) { virtqueue_packed_get_avail_bytes(vq, in_bytes, out_bytes, - max_in_bytes, max_out_bytes); + max_in_bytes, max_out_bytes, + caches); } else { virtqueue_split_get_avail_bytes(vq, in_bytes, out_bytes, - max_in_bytes, max_out_bytes); + max_in_bytes, max_out_bytes, + caches); } =20 return; --=20 2.31.1