From nobody Fri Nov 7 23:12:22 2025 X-Original-To: dev-commits-src-branches@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4d3FFf39nlz6Dmlf; Fri, 07 Nov 2025 23:12:22 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R12" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4d3FFf1P6Tz3bXg; Fri, 07 Nov 2025 23:12:22 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1762557142; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=7IYnIye3J7vy8OjkgYbN76eOv9M21O6zNiLguV5T20Q=; b=vx1Mjfg62MG7VvjW80BbGYBkYMomWWpakxepm4AlZ7pRNvzq3j6ze6dbi0gSL7sTVgX7e7 Ko9Jh7iQaESfYBiaKH8x1yjhKok8M4qhCjn8XHHcLIc6hVxB8fe8nOBF5WrVIxpuRP7Fe3 WbXqcGe2QTAmjvffAhkLa+9hwwmdvMnoi9+e39qua96beSVO5JrCQugkDBsGmkvsOo5C4m gB3Z3rCKphrKj9hNM+LvSQZio/Bpmysn9ym4Cjrx3t9JGchsT31/Jt/si1OepQvBty6ia+ oZn/53adbEYHffgYhyLieDX/l3oKUWBICSgvBiQA+apu1l9wtn4LpQVa9L82Fg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1762557142; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=7IYnIye3J7vy8OjkgYbN76eOv9M21O6zNiLguV5T20Q=; b=EkxHPSRTpc0h6foyJUjj5SGWQIshSl0Mp5ZPpihrtS/iCXdXX99aSgHrqpRUam4RrsaQfS VpGRse5GRlVG2l6LPEz+ppP7YCR9lJ4+uiSIAFAvs5wOQhxN7Xr6OiJiLeyPGuWq9CM6vE OlOYjXP7E4ej9ParisuCVSA+UQgA1hjP42nG0xa1IJlpdD/DaPvUZ8dEmgR5bvWv97zZT4 rwZP56RTRXidZgL+/RcVZQoujaA4lIcTdUh4/21D9lPDfe4Ty+NVKqag1uOBLghFKCDX+4 R3tT4K3mzEi84z8aTBtOdiwP0NydEO4nUERND0AJT6IZJyL0kH5Nnaj4ydSizg== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1762557142; a=rsa-sha256; cv=none; b=WwwVKNE4CHLAHJPogL33TzBpyEVQSOgmk+90K76ZUMsB7SGI9U17s/4qdeteB4u8lCFEha nQLK++f7KI2OX+MtqQjhLnEyB6eR9OssLHML0tOX82wojx80xNAQWMtCMWm9PhGdKpgERG 4l2310f+Iw3lAp1F+eGI1SSPX1U+6zFF8K8PuUew6lE8wWH1iAsR9VJ8E9S2iy0923XOTJ 6Ml0+etwXCkrdhYFfBZZ/UJwQjK1pxkMwMyrPkgsOIRSgym1IvIfaVHAwTD+CoaH5DO/+z lYH1aBmQgZkErWdZKdz3pDh9G2QhDKfQ8y5koYkhc6k/pZHIWvh/FLn2MAXoLw== ARC-Authentication-Results: i=1; mx1.freebsd.org; none Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 4d3FFf0tXnz4Zc; Fri, 07 Nov 2025 23:12:22 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.18.1/8.18.1) with ESMTP id 5A7NCMBO029515; Fri, 7 Nov 2025 23:12:22 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.18.1/8.18.1/Submit) id 5A7NCMkM029512; Fri, 7 Nov 2025 23:12:22 GMT (envelope-from git) Date: Fri, 7 Nov 2025 23:12:22 GMT Message-Id: <202511072312.5A7NCMkM029512@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Colin Percival Subject: git: 69c726c15077 - releng/15.0 - virtio: Fix polling in virtqueue_dequeue() List-Id: Commits to the stable branches of the FreeBSD src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-branches List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-branches@freebsd.org Sender: owner-dev-commits-src-branches@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: cperciva X-Git-Repository: src X-Git-Refname: refs/heads/releng/15.0 X-Git-Reftype: branch X-Git-Commit: 69c726c150772c36854d38e51b6fd921a04caea5 Auto-Submitted: auto-generated The branch releng/15.0 has been updated by cperciva: URL: https://cgit.FreeBSD.org/src/commit/?id=69c726c150772c36854d38e51b6fd921a04caea5 commit 69c726c150772c36854d38e51b6fd921a04caea5 Author: Mark Johnston AuthorDate: 2025-11-04 14:27:33 +0000 Commit: Colin Percival CommitDate: 2025-11-07 23:12:02 +0000 virtio: Fix polling in virtqueue_dequeue() The access of vq->vq_ring.used->idx needs to be volatile-qualified, otherwise the compiler may optimize virtqueue_poll() into an infinite loop if there is no data available upon the first poll. Prior to commit ad17789a8569 this wasn't a problem since an external function call after each poll inhibited the optimization. Approved by: re (cperciva) PR: 289930 MFC after: 3 days Sponsored by: Klara, Inc. Fixes: ad17789a8569 ("virtio: Remove the unused poll method") (cherry picked from commit f999ffdce3813eb946f10999ccffb8275c324469) (cherry picked from commit 72c76047541ab6cc0e989a74e8de4d6e6a1a94b6) --- sys/dev/virtio/virtqueue.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/sys/dev/virtio/virtqueue.c b/sys/dev/virtio/virtqueue.c index cc7a233d60ee..41e01549c8b2 100644 --- a/sys/dev/virtio/virtqueue.c +++ b/sys/dev/virtio/virtqueue.c @@ -580,7 +580,8 @@ virtqueue_dequeue(struct virtqueue *vq, uint32_t *len) void *cookie; uint16_t used_idx, desc_idx; - if (vq->vq_used_cons_idx == vq_htog16(vq, vq->vq_ring.used->idx)) + if (vq->vq_used_cons_idx == + vq_htog16(vq, atomic_load_16(&vq->vq_ring.used->idx))) return (NULL); used_idx = vq->vq_used_cons_idx++ & (vq->vq_nentries - 1);