[Intel-wired-lan] [PATCH iwl-net v4] ice: fix locking in ice_dcb_rebuild()

[Bart Van Assche]

On 3/20/26 2:28 PM, Bart Van Assche wrote:
> Move the mutex_lock() call up to prevent that DCB settings change after
> the first ice_query_port_ets() call. The second ice_query_port_ets()
> call in ice_dcb_rebuild() is already protected by pf->tc_mutex.
> 
> This also fixes a bug in an error path, as before taking the first
> "goto dcb_error" in the function jumped over mutex_lock() to
> mutex_unlock().
> 
> This bug has been detected by the clang thread-safety analyzer.
> 
> Cc: Aleksandr Loktionov <aleksandr.loktionov at intel.com>
> Cc: intel-wired-lan at lists.osuosl.org
> Fixes: 242b5e068b25 ("ice: Fix DCB rebuild after reset")
> Signed-off-by: Bart Van Assche <bvanassche at acm.org>
> ---
> 
> v4 (this patch): Changed "[PATCH] iwl-net:" into "[PATCH iwl-net]".
> 
> v3 (2026-03-20): Modified patch description. See also
>    https://lore.kernel.org/all/20260223220102.2158611-20-bart.vanassche@linux.dev/#t
> 
> v2 (2026-02-23): Combined the two patches into one patch and
>    increased the amount of code covered by tc_mutex. See also
>    https://lore.kernel.org/all/20260223220102.2158611-20-bart.vanassche@linux.dev/
> 
> v1 (2025-02-06): Two patches. See also
>    https://lore.kernel.org/all/20250206175114.1974171-16-bvanassche@acm.org/
> 
>   drivers/net/ethernet/intel/ice/ice_dcb_lib.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_dcb_lib.c b/drivers/net/ethernet/intel/ice/ice_dcb_lib.c
> index bd77f1c001ee..78ded6876581 100644
> --- a/drivers/net/ethernet/intel/ice/ice_dcb_lib.c
> +++ b/drivers/net/ethernet/intel/ice/ice_dcb_lib.c
> @@ -537,14 +537,14 @@ void ice_dcb_rebuild(struct ice_pf *pf)
>   	struct ice_dcbx_cfg *err_cfg;
>   	int ret;
>   
> +	mutex_lock(&pf->tc_mutex);
> +
>   	ret = ice_query_port_ets(pf->hw.port_info, &buf, sizeof(buf), NULL);
>   	if (ret) {
>   		dev_err(dev, "Query Port ETS failed\n");
>   		goto dcb_error;
>   	}
>   
> -	mutex_lock(&pf->tc_mutex);
> -
>   	if (!pf->hw.port_info->qos_cfg.is_sw_lldp)
>   		ice_cfg_etsrec_defaults(pf->hw.port_info);
>   

Hi Tony,

It seems like this patch has not made it into Linux kernel v7.1-rc. Do
you agree that this patch is ready to be merged? I checked that it still
applies to Linus' master branch.

Thanks,

Bart.