Re: [net-next,PatchV2,1/2] octeontx2-af: Mailbox handlers to fetch DMAC filter drop counter

[Jakub Kicinski <kuba@kernel.org>]

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---
octeontx2-af: Mailbox handlers to fetch DMAC filter drop counter

This patch adds mailbox handler support to read the DMAC filter drop
counter from CGX and RPM MAC blocks.

> diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu_cgx.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu_cgx.c
> index 3abd750a4bd7..aef0087174b7 100644
> --- a/drivers/net/ethernet/marvell/octeontx2/af/rvu_cgx.c
> +++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu_cgx.c

[ ... ]

> +int rvu_mbox_handler_cgx_get_dmacflt_dropped_pktcnt(struct rvu *rvu,
> +						    struct msg_req *req,
> +						    struct cgx_dmac_filter_drop_cnt *rsp)
> +{
> +	int pf = rvu_get_pf(rvu->pdev, req->hdr.pcifunc);
> +	struct mac_ops *mac_ops;
> +	u8 cgx_id, lmac_id;
> +	void *cgxd;
> +
> +	rvu_get_cgx_lmac_id(rvu->pf2cgxlmac_map[pf], &cgx_id, &lmac_id);
> +	cgxd = rvu_cgx_pdata(cgx_id, rvu);
> +	mac_ops = get_mac_ops(cgxd);
> +
> +	if (!mac_ops->get_dmacflt_dropped_pktcnt)
              ^^^^^^^^^

Can mac_ops be NULL here? When a PF is not CGX-mapped, pf2cgxlmac_map[pf]
returns 0xFF, which extracts cgx_id=0xF. Then rvu_cgx_pdata() returns
NULL if cgx_id >= cgx_cnt_max. Subsequently, get_mac_ops(NULL) returns
NULL, and this line would dereference a NULL pointer.

Other similar handlers in this file check is_pf_cgxmapped() or
is_cgx_config_permitted() before proceeding with the CGX operations.
For example, rvu_mbox_handler_cgx_fec_stats() and
rvu_mbox_handler_cgx_features_get() both validate the PF mapping first.

Should this handler also include a validation check like:

    if (!is_pf_cgxmapped(rvu, pf))
        return 0;

> +		return 0;
> +
> +	rsp->count =  mac_ops->get_dmacflt_dropped_pktcnt(cgxd, lmac_id);
> +	return 0;
> +}
-- 
pw-bot: cr