Re: [PATCH v3 net-next 14/14] net: enetc: use kzalloc_flex() for enetc_psfp_gate allocation

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] This problem wasn't introduced by this patch, but the error rollback path in `enetc_psfp_hw_set()` breaks existing hardware state by unconditionally reverting shared resources.
--

commit 6d57d48e343452bcc08a00c11bfae2b630b9f68a
Author: Wei Fang <wei.fang@nxp.com>

net: enetc: use kzalloc_flex() for enetc_psfp_gate allocation

This patch replaces the open-coded struct_size() + kzalloc() pattern with
the kzalloc_flex() helper when allocating struct enetc_psfp_gate. This
removes the intermediate entries_size local variable and makes the
allocation site more concise.

> diff --git a/drivers/net/ethernet/freescale/enetc/enetc_qos.c b/drivers/net/ethernet/freescale/enetc/enetc_qos.c
> index 7b17bca24f260..2aa0fcaafcd23 100644
> --- a/drivers/net/ethernet/freescale/enetc/enetc_qos.c
> +++ b/drivers/net/ethernet/freescale/enetc/enetc_qos.c
[ ... ]
> @@ -1242,8 +1241,7 @@ static int enetc_psfp_parse_clsflower(struct enetc_ndev_priv *priv,
>  		goto free_filter;
>  	}
>  
> -	entries_size = struct_size(sgi, entries, entryg->gate.num_entries);
> -	sgi = kzalloc(entries_size, GFP_KERNEL);
> +	sgi = kzalloc_flex(*sgi, entries, entryg->gate.num_entries);
>  	if (!sgi) {
>  		err = -ENOMEM;
>  		goto free_filter;

[Severity: High]
This isn't a bug introduced by this patch, but while reviewing this code I
noticed an issue with the error rollback path in enetc_psfp_hw_set() which is
called shortly after this allocation.

When enetc_psfp_hw_set() fails, it unconditionally disables the stream gate in
hardware:

drivers/net/ethernet/freescale/enetc/enetc_qos.c:enetc_psfp_hw_set() {
    ...
    if (fmi) {
        err = enetc_flowmeter_hw_set(priv, fmi, true);
        if (err)
            goto revert_sgi;
    }
    ...
revert_sgi:
    enetc_streamgate_hw_set(priv, sgi, false);
    ...
}

Because enetc_psfp_parse_clsflower() allows stream gates to be shared and
reused across multiple filters (via enetc_get_gate_by_index()), could this
rollback path break existing hardware state?

If a user adds a new tc-flower filter that reuses an existing stream gate
index, and a subsequent hardware setup step fails, the error handling path
blindly calls enetc_streamgate_hw_set(..., false). Will this disable the
already active stream gate and break all other filters relying on it?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260703101328.550714-1-wei.fang@oss.nxp.com?part=14