Re: [net-next,v3,05/13] octeontx2-af: npc: cn20k: Allocate default MCAM indexes
From: Jakub Kicinski
Date: Sat Jan 10 2026 - 17:59:36 EST
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octeontx2-af: npc: cn20k: Allocate default MCAM indexes
This patch allocates MCAM indexes for promiscuous, multicast, broadcast,
and unicast traffic when the NIX LF is attached to the PF/VF, rather than
reserving entries upfront.
> diff --git a/drivers/net/ethernet/marvell/octeontx2/af/cn20k/npc.c b/drivers/net/ethernet/marvell/octeontx2/af/cn20k/npc.c
> index 88d7f65d246c..cc5a2fde02b9 100644
> --- a/drivers/net/ethernet/marvell/octeontx2/af/cn20k/npc.c
> +++ b/drivers/net/ethernet/marvell/octeontx2/af/cn20k/npc.c
[ ... ]
> +int npc_cn20k_dft_rules_alloc(struct rvu *rvu, u16 pcifunc)
> +{
> + u16 mcam_idx[4] = { 0 }, pf_ucast, pf_pcifunc;
> + struct npc_mcam_alloc_entry_req req = { 0 };
> + struct npc_mcam_alloc_entry_rsp rsp = { 0 };
[ ... ]
> + ret = rvu_mbox_handler_npc_mcam_alloc_entry(rvu, &req, &rsp);
> +
> + /* successfully allocated index */
> + if (!ret) {
> + /* Copy indexes to local array */
> + for (i = 0; i < cnt; i++)
> + mcam_idx[i] = rsp.entry_list[i];
> +
> + goto chk_sanity;
> + }
[ ... ]
> +chk_sanity:
[ ... ]
> + /* LBK */
> + if (is_lbk_vf(rvu, pcifunc)) {
> + index = NPC_DFT_RULE_ID_MK(pcifunc, NPC_DFT_RULE_PROMISC_ID);
> + ret = xa_insert(&npc_priv.xa_pf2dfl_rmap, index,
> + xa_mk_value(mcam_idx[0]), GFP_KERNEL);
> + if (ret) {
[ ... ]
> + ret = -EFAULT;
> + goto err;
> + }
> +
> + goto done;
> + }
> +
> + /* VF */
> + if (is_vf(pcifunc)) {
> + index = NPC_DFT_RULE_ID_MK(pcifunc, NPC_DFT_RULE_UCAST_ID);
> + ret = xa_insert(&npc_priv.xa_pf2dfl_rmap, index,
> + xa_mk_value(mcam_idx[0]), GFP_KERNEL);
> + if (ret) {
[ ... ]
> + ret = -EFAULT;
> + goto err;
> + }
> +
> + goto done;
> + }
> +
> + /* PF */
> + for (i = NPC_DFT_RULE_START_ID, k = 0; i < NPC_DFT_RULE_MAX_ID &&
> + k < cnt; i++, k++) {
> + index = NPC_DFT_RULE_ID_MK(pcifunc, i);
> + ret = xa_insert(&npc_priv.xa_pf2dfl_rmap, index,
> + xa_mk_value(mcam_idx[k]), GFP_KERNEL);
> + if (ret) {
[ ... ]
> + ret = -EFAULT;
> + goto err;
> + }
> + }
> +
> +done:
> + return 0;
> +err:
> + /* TODO: handle errors */
> + return ret;
> +}
If xa_insert() fails here, the MCAM entries that were allocated earlier
via rvu_mbox_handler_npc_mcam_alloc_entry() are not freed before
returning the error. Could this leak the MCAM entries?
The comment indicates this is known incomplete error handling. For the
PF case, partial xa_insert failures in the loop could also leave some
entries inserted in the xarray while others are not, leading to an
inconsistent state.