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

[Bart Van Assche via Intel-wired-lan <intel-wired-lan@osuosl.org>]

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);