[PATCH net-next 1/4] eth: mpnic: use WRITE_ONCE() for BDQ head and tail updates
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From: Daniel Zahka <daniel.zahka@gmail.com>
Date: 2026-10-01 16:39:19
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Subsystem:
meta ethernet drivers, networking drivers, the rest · Maintainers:
Alexander Duyck, Jakub Kicinski, Andrew Lunn, "David S. Miller", Eric Dumazet, Paolo Abeni, Linus Torvalds
Convert writes to BDQ ring head and tail in the NAPI path to WRITE_ONCE(), so that a buffer NAPI depletion check task later in the series can READ_ONCE() those fields from a workqueue outside of NAPI. The remaining writers in mpnic_enable_bdq() and mpnic_clean_bdq() run with NAPI disabled and the instance lock, so don't bother converting them. The NAPI depletion check later in the series will run under the instance lock. Signed-off-by: Daniel Zahka <daniel.zahka@gmail.com> --- drivers/net/ethernet/meta/mpnic/mpnic_txrx.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/meta/mpnic/mpnic_txrx.c b/drivers/net/ethernet/meta/mpnic/mpnic_txrx.c
index edb07b7f334b..49061c7316d5 100644
--- a/drivers/net/ethernet/meta/mpnic/mpnic_txrx.c
+++ b/drivers/net/ethernet/meta/mpnic/mpnic_txrx.c@@ -384,7 +384,7 @@ static unsigned int __mpnic_fill_bdq(struct mpnic_ring *bdq) static void __mpnic_bdq_commit_tail(struct mpnic_ring *bdq, unsigned int tail) { if (bdq->tail != tail) { - bdq->tail = tail; + WRITE_ONCE(bdq->tail, tail); writeq(tail, bdq->doorbell); }
@@ -483,7 +483,7 @@ mpnic_pkt_prepare(u64 rcd, struct mpnic_rcq_state *state, pg_start = mpnic_hdr_pg_start(pg_off); page = mpnic_page_pool_get(&state->hdr, &qt->sub0, pg_idx); - qt->sub0.head = (pg_idx + 1) & qt->sub0.size_mask; + WRITE_ONCE(qt->sub0.head, (pg_idx + 1) & qt->sub0.size_mask); /* Short-cut the end calculation if the page is fully consumed */ pg_end = fin ? page_size(page) : mpnic_hdr_pg_end(pg_off, len);
@@ -513,7 +513,7 @@ mpnic_add_rx_frag(u64 rcd, struct mpnic_rcq_state *state, struct page *page; page = mpnic_page_pool_get(&state->payld, &qt->sub1, pg_idx); - qt->sub1.head = (pg_idx + 1) & qt->sub1.size_mask; + WRITE_ONCE(qt->sub1.head, (pg_idx + 1) & qt->sub1.size_mask); truesz = (fin ? page_size(page) : ALIGN(pg_off + len, 128)) - pg_off;
--
2.52.0