[PATCH net] pds_core: order completion reads after the ownership check
From: Nikhil P. Rao <hidden>
Date: 2026-07-14 20:42:05
Subsystem:
amd pds core driver, networking drivers, the rest · Maintainers:
Brett Creeley, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
pdsc_process_adminq() and pdsc_process_notifyq() decide a completion is
valid from its ownership field - the color bit for the adminq, the event
id for the notifyq - then read the rest of the descriptor, with no
barrier in between.
On a weakly ordered architecture the CPU may read the payload first. Add
dma_rmb() between the ownership read and the payload reads.
Fixes: 7e82a8745b95 ("pds_core: Prevent race issues involving the adminq")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260629200358.2626129-1-nikhil.rao%40amd.com?part=2
Signed-off-by: Nikhil P. Rao <redacted>
Reviewed-by: Eric Joyner <redacted>
---
drivers/net/ethernet/amd/pds_core/adminq.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/amd/pds_core/adminq.c b/drivers/net/ethernet/amd/pds_core/adminq.c
index 097bb092bdb8..eadb4b604fbe 100644
--- a/drivers/net/ethernet/amd/pds_core/adminq.c
+++ b/drivers/net/ethernet/amd/pds_core/adminq.c@@ -18,7 +18,13 @@ static int pdsc_process_notifyq(struct pdsc_qcq *qcq) comp = cq_info->comp; eid = le64_to_cpu(comp->event.eid); while (eid > pdsc->last_eid) { - u16 ecode = le16_to_cpu(comp->event.ecode); + u16 ecode; + + /* Order the payload read after the event id, the field the + * driver uses to detect a new completion. + */ + dma_rmb(); + ecode = le16_to_cpu(comp->event.ecode); switch (ecode) { case PDS_EVENT_LINK_CHANGE:
@@ -101,6 +107,10 @@ void pdsc_process_adminq(struct pdsc_qcq *qcq) spin_lock_irqsave(&pdsc->adminq_lock, irqflags); comp = cq->info[cq->tail_idx].comp; while (pdsc_color_match(comp->color, cq->done_color)) { + /* Order the payload reads after the color bit, the field the + * driver uses to detect a new completion. + */ + dma_rmb(); q_info = &q->info[q->tail_idx]; q->tail_idx = (q->tail_idx + 1) & (q->num_descs - 1);
--
2.43.0