From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sender4-op-o15.zoho.com (sender4-op-o15.zoho.com [136.143.188.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9ACEC403E85; Tue, 9 Jun 2026 12:08:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.188.15 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781006903; cv=pass; b=j1ienQZTND4vIYzNPH3T6rCzobTW2wg0G+f75Uarf9xNAWv3MYNFS0Ea/6bjHk0XNQaBy0Zo3e+rs0oMIO3brWRHVHmK5dLEKNfxK7XpbMDjUTfR/RIT653SdxtDQYQdBfFaSgO3+ZkhmGHzrO90LJE9pGk1OnbdLuhKww24JqA= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781006903; c=relaxed/simple; bh=G0IOvAY7QjaiQjumjwhpfVDBmEKpe3sSiqm2aC2Qdcg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pWkUKembN1jIPkSItV6cK1m6w9QA7par8T12tTEYFhBPquOUoohh6so0emO6ytr2obSXTkmQP7EUmxdCf8QVy4kN2Z9yTWP++a/e+d10K9edH4A1QwgsBWXFSR7wQIIuekY/+aAM3ntHY1C28PloFonV4YjEeV72AoBmd+nTmCc= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.beauty; spf=pass smtp.mailfrom=linux.beauty; dkim=pass (1024-bit key) header.d=linux.beauty header.i=me@linux.beauty header.b=s2KyggbR; arc=pass smtp.client-ip=136.143.188.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.beauty Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.beauty Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.beauty header.i=me@linux.beauty header.b="s2KyggbR" ARC-Seal: i=1; a=rsa-sha256; t=1781006885; cv=none; d=zohomail.com; s=zohoarc; b=AORPKi3L4bUcSUKx7oZysQc4fS5pvTLoA6uUg0kYaCR48NwKjbJxTYRCj+PUP3MqUNb0kjYk0VkwS3Y9aaWa4RQMHGGUYFIHE7Bo8sBnpO3T6flJv90+N/1QFF2BlZX/p5/PsP5KWJd12ZnAP4OpnWbKMw3trbPAfm7xxhg0r9w= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1781006885; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=Hl4Phc/SGptDlD9wvlzfeMrOBpaGLDvn8OL4eByCY20=; b=RnwpO4QhMROiuuAMIzal/lG5ltMKuakhu4ry4tZ/+cCETcVf8CArwWIkB/6XPkX2F7i04RcBcqDNq5Qh9WVHX82B0XCGAJsB/1Yz19IDYW0R9G5MtLGvjNuaX9Hc3KJXQCMxdbchkY9ZD/cYLPq/39C/j2I8vHwT1UP/g1Er1XA= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=linux.beauty; spf=pass smtp.mailfrom=me@linux.beauty; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1781006884; s=zmail; d=linux.beauty; i=me@linux.beauty; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:In-Reply-To:References:MIME-Version:Content-Transfer-Encoding:Message-Id:Reply-To; bh=Hl4Phc/SGptDlD9wvlzfeMrOBpaGLDvn8OL4eByCY20=; b=s2KyggbRXZGxJcpacfd2pWuE/oyCJ9j1WdLgEtXPp/yY/IYpQJA9Jn7CrYaiBZg5 NmWVG4hb6LxQYNn9d/qMscNSHpbfx/Brvbw2gUyPgllcmlA83HRMufne3OzRPPbW6Nb vNO7U+MnxXBfuKOPUwk1qaOTNnyiSfrBLI1hCVQg= Received: by mx.zohomail.com with SMTPS id 1781006883104423.15836000045647; Tue, 9 Jun 2026 05:08:03 -0700 (PDT) From: Li Chen To: Pankaj Gupta , Dan Williams , Vishal Verma , Dave Jiang , Ira Weiny , Alison Schofield , virtualization@lists.linux.dev, nvdimm@lists.linux.dev Cc: linux-kernel@vger.kernel.org, Li Chen Subject: [PATCH v4 4/7] nvdimm: virtio_pmem: use READ_ONCE()/WRITE_ONCE() for wait flags Date: Tue, 9 Jun 2026 20:07:18 +0800 Message-ID: <20260609120726.1714780-5-me@linux.beauty> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260609120726.1714780-1-me@linux.beauty> References: <20260609120726.1714780-1-me@linux.beauty> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-ZohoMailClient: External Use READ_ONCE()/WRITE_ONCE() for the wait_event() flags (done and wq_buf_avail). They are observed by waiters without pmem_lock, so make the accesses explicit single loads/stores and avoid compiler reordering/caching across the wait/wake paths. Signed-off-by: Li Chen --- v2->v3: - Split out READ_ONCE()/WRITE_ONCE() updates from patch 3/7 (no functional change intended). v3->v4: - Rebased onto v7.1-rc7 and renumbered after the flush error patches. drivers/nvdimm/nd_virtio.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c index 16ee5a47b9938..f8c0604edde51 100644 --- a/drivers/nvdimm/nd_virtio.c +++ b/drivers/nvdimm/nd_virtio.c @@ -18,9 +18,9 @@ static void virtio_pmem_wake_one_waiter(struct virtio_pmem *vpmem) req_buf = list_first_entry(&vpmem->req_list, struct virtio_pmem_request, list); - req_buf->wq_buf_avail = true; + list_del_init(&req_buf->list); + WRITE_ONCE(req_buf->wq_buf_avail, true); wake_up(&req_buf->wq_buf); - list_del(&req_buf->list); } /* The interrupt handler */ @@ -34,7 +34,7 @@ void virtio_pmem_host_ack(struct virtqueue *vq) spin_lock_irqsave(&vpmem->pmem_lock, flags); while ((req_data = virtqueue_get_buf(vq, &len)) != NULL) { virtio_pmem_wake_one_waiter(vpmem); - req_data->done = true; + WRITE_ONCE(req_data->done, true); wake_up(&req_data->host_acked); } spin_unlock_irqrestore(&vpmem->pmem_lock, flags); @@ -66,7 +66,7 @@ static int virtio_pmem_flush(struct nd_region *nd_region) if (!req_data) return -ENOMEM; - req_data->done = false; + WRITE_ONCE(req_data->done, false); init_waitqueue_head(&req_data->host_acked); init_waitqueue_head(&req_data->wq_buf); INIT_LIST_HEAD(&req_data->list); @@ -87,12 +87,12 @@ static int virtio_pmem_flush(struct nd_region *nd_region) GFP_ATOMIC)) == -ENOSPC) { dev_info(&vdev->dev, "failed to send command to virtio pmem device, no free slots in the virtqueue\n"); - req_data->wq_buf_avail = false; + WRITE_ONCE(req_data->wq_buf_avail, false); list_add_tail(&req_data->list, &vpmem->req_list); spin_unlock_irqrestore(&vpmem->pmem_lock, flags); /* A host response results in "host_ack" getting called */ - wait_event(req_data->wq_buf, req_data->wq_buf_avail); + wait_event(req_data->wq_buf, READ_ONCE(req_data->wq_buf_avail)); spin_lock_irqsave(&vpmem->pmem_lock, flags); } err1 = virtqueue_kick(vpmem->req_vq); @@ -106,7 +106,7 @@ static int virtio_pmem_flush(struct nd_region *nd_region) err = -EIO; } else { /* A host response results in "host_ack" getting called */ - wait_event(req_data->host_acked, req_data->done); + wait_event(req_data->host_acked, READ_ONCE(req_data->done)); err = le32_to_cpu(req_data->resp.ret); } -- 2.52.0