From: Li Chen <me@linux.beauty>
To: Pankaj Gupta <pankaj.gupta.linux@gmail.com>,
Vishal Verma <vishal.l.verma@intel.com>,
Dave Jiang <dave.jiang@intel.com>,
Alison Schofield <alison.schofield@intel.com>,
virtualization@lists.linux.dev, nvdimm@lists.linux.dev
Cc: linux-kernel@vger.kernel.org, Li Chen <me@linux.beauty>
Subject: [PATCH v7 07/12] nvdimm: virtio_pmem: use READ_ONCE()/WRITE_ONCE() for wait flags
Date: Tue, 30 Jun 2026 17:23:32 +0800 [thread overview]
Message-ID: <20260630092338.2094628-8-me@linux.beauty> (raw)
In-Reply-To: <20260630092338.2094628-1-me@linux.beauty>
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.
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Signed-off-by: Li Chen <me@linux.beauty>
---
Changes in v7:
- Add Pankaj's Acked-by.
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 fcb26a595d7c6..8c0d4347938a1 100644
--- a/drivers/nvdimm/nd_virtio.c
+++ b/drivers/nvdimm/nd_virtio.c
@@ -24,9 +24,9 @@ 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 */
@@ -40,7 +40,7 @@ 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);
@@ -72,7 +72,7 @@ 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);
@@ -93,12 +93,12 @@ 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);
@@ -112,7 +112,7 @@ 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
next prev parent reply other threads:[~2026-06-30 9:24 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-30 9:23 [PATCH v7 00/12] nvdimm: virtio_pmem: fix flush/request failure paths Li Chen
2026-06-30 9:23 ` [PATCH v7 01/12] nvdimm: preserve flush callback -ENOMEM Li Chen
2026-06-30 9:23 ` [PATCH v7 02/12] nvdimm: pmem: keep PREFLUSH before data writes Li Chen
2026-06-30 9:23 ` [PATCH v7 03/12] nvdimm: pmem: guard data loop for dataless bios Li Chen
2026-06-30 9:23 ` [PATCH v7 04/12] nvdimm: virtio_pmem: stop allocating child flush bio Li Chen
2026-06-30 9:23 ` [PATCH v7 05/12] nvdimm: virtio_pmem: use GFP_NOIO for flush requests Li Chen
2026-06-30 9:23 ` [PATCH v7 06/12] nvdimm: virtio_pmem: always wake -ENOSPC waiters Li Chen
2026-06-30 9:23 ` Li Chen [this message]
2026-06-30 9:23 ` [PATCH v7 08/12] nvdimm: virtio_pmem: refcount requests for token lifetime Li Chen
2026-06-30 9:23 ` [PATCH v7 09/12] nvdimm: virtio_pmem: publish done with release/acquire Li Chen
2026-06-30 9:23 ` [PATCH v7 10/12] nvdimm: virtio_pmem: isolate DMA request buffers Li Chen
2026-06-30 9:23 ` [PATCH v7 11/12] nvdimm: virtio_pmem: converge broken virtqueue to -EIO Li Chen
2026-06-30 9:23 ` [PATCH v7 12/12] nvdimm: virtio_pmem: drain requests in freeze Li Chen
2026-06-30 9:47 ` [PATCH v7 00/12] nvdimm: virtio_pmem: fix flush/request failure paths Pankaj Gupta
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260630092338.2094628-8-me@linux.beauty \
--to=me@linux.beauty \
--cc=alison.schofield@intel.com \
--cc=dave.jiang@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=nvdimm@lists.linux.dev \
--cc=pankaj.gupta.linux@gmail.com \
--cc=virtualization@lists.linux.dev \
--cc=vishal.l.verma@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox