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

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

[Bart Van Assche via Intel-wired-lan]

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@intel.com>
Cc: intel-wired-lan@lists.osuosl.org
Fixes: 242b5e068b25 ("ice: Fix DCB rebuild after reset")
Signed-off-by: Bart Van Assche <bvanassche@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);
 

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

[Loktionov, Aleksandr]

> -----Original Message-----
> From: Bart Van Assche <bvanassche@acm.org>
> Sent: Friday, March 20, 2026 10:28 PM
> To: Nguyen, Anthony L <anthony.l.nguyen@intel.com>
> Cc: Kitszel, Przemyslaw <przemyslaw.kitszel@intel.com>; intel-wired-
> lan@lists.osuosl.org; Bart Van Assche <bvanassche@acm.org>; Loktionov,
> Aleksandr <aleksandr.loktionov@intel.com>
> Subject: [PATCH iwl-net v4] ice: fix locking in ice_dcb_rebuild()
> 
> 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@intel.com>
> Cc: intel-wired-lan@lists.osuosl.org
> Fixes: 242b5e068b25 ("ice: Fix DCB rebuild after reset")
> Signed-off-by: Bart Van Assche <bvanassche@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);
> 

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>

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

[Przemek Kitszel]

On 3/20/26 22:28, 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@intel.com>
> Cc: intel-wired-lan@lists.osuosl.org
> Fixes: 242b5e068b25 ("ice: Fix DCB rebuild after reset")
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---

thank you!
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>

> 
> 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

this is a link to version from Feb, I would expect to see "v3" link
here, not need to repost to fix that ofc

> 
> 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);
>