[PATCH net v5 4/6] bnxt_en: Handle buffer allocation failure in bnxt_rx_ring_reset()

[Joe Damato <joe@dama.to>]

bnxt_rx_ring_reset() frees the ring buffers and then reallocates them,
ignoring the result.

bnxt_alloc_one_rx_ring() can fail in bnxt_alloc_one_tpa_info_data(), which
returns -ENOMEM on the first failed allocation and leaves the remaining
rxr->rx_tpa[] entries zeroed.

The error isn't propagated up, so the loop in bnxt_rx_ring_reset
continues and at the end the code re-enables TPA with partially
unallocated rx_tpa array.

This means that when the agg_id from hardware is mapped to a SW index in
rxr->rx_tpa[], an uninitialized slot can be chosen which would hand a
zero DMA address to the device.

Fix this by falling back to a global reset, which is what the existing
code already does when other functions fail, but unlike the other
failure cases this particular failure has to return because TPA can't
be re-enabled since the allocation failed.

Fixes: 8fbf58e17dce ("bnxt_en: Implement RX ring reset in response to buffer errors.")
Reported-by: Sashiko <sashiko-bot+sashiko@kernel.org>
Link: https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260828190900.1767611-1-joe%40dama.to
Cc: stable@vger.kernel.org
Signed-off-by: Joe Damato <joe@dama.to>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 3755a30f8d40..a8e5fdfcdf59 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -14604,7 +14604,14 @@ static void bnxt_rx_ring_reset(struct bnxt *bp)
 		rxr->rx_sw_agg_prod = 0;
 		rxr->rx_next_cons = 0;
 		rxr->bnapi->in_reset = false;
-		bnxt_alloc_one_rx_ring(bp, i);
+		rc = bnxt_alloc_one_rx_ring(bp, i);
+		if (rc) {
+			netdev_warn(bp->dev, "RX ring reset failed to allocate buffers, rc = %d, falling back to global reset\n",
+				    rc);
+			bnxt_reset_task(bp, true);
+			bnxt_rtnl_unlock_sp(bp);
+			return;
+		}
 		cpr = &rxr->bnapi->cp_ring;
 		cpr->sw_stats->rx.rx_resets++;
 		if (bp->flags & BNXT_FLAG_AGG_RINGS)
-- 
2.53.0-Meta