[Intel-wired-lan] [PATCH 6.12 179/272] ice: fix locking in ice_dcb_rebuild()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bvanassche@acm.org>

[ Upstream commit 0ded1f36ba4021cba50513e80be6b6e173710168 ]

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: intel-wired-lan@lists.osuosl.org
Fixes: 242b5e068b25 ("ice: Fix DCB rebuild after reset")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Tested-by: Arpana Arland <arpanax.arland@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260506-jk-iwl-net-2026-05-04-v2-6-a5ea4dc837a9@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.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 a7c5108328240..d185b1aba7a47 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);
 
-- 
2.53.0