Reapply "bnxt_en: bring back rtnl_lock() in the bnxt_open() path"

This reverts commit 850d9248d2eac662f869c766a598c877690c74e5.
This reapplies commit 325eb217e41f ("bnxt_en: bring back rtnl_lock()
in the bnxt_open() path").

Breno reports a lockdep warning in bnxt. During FW reset the driver
may end up calling netif_set_real_num_tx_queues() (if queue count
changes), so calls to bnxt_open() still require rtnl_lock.

  net/sched/sch_generic.c:1416 suspicious rcu_dereference_protected() usage!

   dev_qdisc_change_real_num_tx+0x54/0xe0
   netif_set_real_num_tx_queues+0x4ed/0xa80
   __bnxt_open_nic+0x9cb/0x3490
   bnxt_open+0x1cb/0x370
   bnxt_fw_reset_task+0x80d/0x1e80
   process_scheduled_works+0x9c1/0x13b0

The reverted commit was just an optimization / experiment
so let's go back to taking the lock.

Reported-by: Breno Leitao <leitao@debian.org>
Link: https://lore.kernel.org/ah726OtFX-Qw3U-R@gmail.com
Fixes: 850d9248d2ea ("Revert "bnxt_en: bring back rtnl_lock() in the bnxt_open() path"")
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Reviewed-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20260603195845.2574426-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 29 insertions, 7 deletions

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 008c34cff7b4..35e1f8f663c7 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -14388,13 +14388,28 @@ static void bnxt_unlock_sp(struct bnxt *bp)
 	netdev_unlock(bp->dev);
 }
 
+/* Same as bnxt_lock_sp() with additional rtnl_lock */
+static void bnxt_rtnl_lock_sp(struct bnxt *bp)
+{
+	clear_bit(BNXT_STATE_IN_SP_TASK, &bp->state);
+	rtnl_lock();
+	netdev_lock(bp->dev);
+}
+
+static void bnxt_rtnl_unlock_sp(struct bnxt *bp)
+{
+	set_bit(BNXT_STATE_IN_SP_TASK, &bp->state);
+	netdev_unlock(bp->dev);
+	rtnl_unlock();
+}
+
 /* Only called from bnxt_sp_task() */
 static void bnxt_reset(struct bnxt *bp, bool silent)
 {
-	bnxt_lock_sp(bp);
+	bnxt_rtnl_lock_sp(bp);
 	if (test_bit(BNXT_STATE_OPEN, &bp->state))
 		bnxt_reset_task(bp, silent);
-	bnxt_unlock_sp(bp);
+	bnxt_rtnl_unlock_sp(bp);
 }
 
 /* Only called from bnxt_sp_task() */
@@ -14402,9 +14417,9 @@ static void bnxt_rx_ring_reset(struct bnxt *bp)
 {
 	int i;
 
-	bnxt_lock_sp(bp);
+	bnxt_rtnl_lock_sp(bp);
 	if (!test_bit(BNXT_STATE_OPEN, &bp->state)) {
-		bnxt_unlock_sp(bp);
+		bnxt_rtnl_unlock_sp(bp);
 		return;
 	}
 	/* Disable and flush TPA before resetting the RX ring */
@@ -14443,7 +14458,7 @@ static void bnxt_rx_ring_reset(struct bnxt *bp)
 	}
 	if (bp->flags & BNXT_FLAG_TPA)
 		bnxt_set_tpa(bp, true);
-	bnxt_unlock_sp(bp);
+	bnxt_rtnl_unlock_sp(bp);
 }
 
 static void bnxt_fw_fatal_close(struct bnxt *bp)
@@ -15358,15 +15373,17 @@ static void bnxt_fw_reset_task(struct work_struct *work)
 		bp->fw_reset_state = BNXT_FW_RESET_STATE_OPENING;
 		fallthrough;
 	case BNXT_FW_RESET_STATE_OPENING:
-		while (!netdev_trylock(bp->dev)) {
+		while (!rtnl_trylock()) {
 			bnxt_queue_fw_reset_work(bp, HZ / 10);
 			return;
 		}
+		netdev_lock(bp->dev);
 		rc = bnxt_open(bp->dev);
 		if (rc) {
 			netdev_err(bp->dev, "bnxt_open() failed during FW reset\n");
 			bnxt_fw_reset_abort(bp, rc);
 			netdev_unlock(bp->dev);
+			rtnl_unlock();
 			goto ulp_start;
 		}
 
@@ -15386,6 +15403,7 @@ static void bnxt_fw_reset_task(struct work_struct *work)
 			bnxt_dl_health_fw_status_update(bp, true);
 		}
 		netdev_unlock(bp->dev);
+		rtnl_unlock();
 		bnxt_ulp_start(bp);
 		bnxt_reenable_sriov(bp);
 		netdev_lock(bp->dev);
@@ -16379,7 +16397,7 @@ err_reset:
 		   rc);
 	napi_enable_locked(&bnapi->napi);
 	bnxt_db_nq_arm(bp, &cpr->cp_db, cpr->cp_raw_cons);
-	bnxt_reset_task(bp, true);
+	netif_close(dev);
 	return rc;
 }
 
@@ -17230,6 +17248,7 @@ static int bnxt_resume(struct device *device)
 	struct bnxt *bp = netdev_priv(dev);
 	int rc = 0;
 
+	rtnl_lock();
 	netdev_lock(dev);
 	rc = pci_enable_device(bp->pdev);
 	if (rc) {
@@ -17274,6 +17293,7 @@ static int bnxt_resume(struct device *device)
 
 resume_exit:
 	netdev_unlock(bp->dev);
+	rtnl_unlock();
 	if (!rc) {
 		bnxt_ulp_start(bp);
 		bnxt_reenable_sriov(bp);
@@ -17445,6 +17465,7 @@ static void bnxt_io_resume(struct pci_dev *pdev)
 	int err;
 
 	netdev_info(bp->dev, "PCI Slot Resume\n");
+	rtnl_lock();
 	netdev_lock(netdev);
 
 	err = bnxt_hwrm_func_qcaps(bp);
@@ -17462,6 +17483,7 @@ static void bnxt_io_resume(struct pci_dev *pdev)
 		netif_device_attach(netdev);
 
 	netdev_unlock(netdev);
+	rtnl_unlock();
 	if (!err) {
 		bnxt_ulp_start(bp);
 		bnxt_reenable_sriov(bp);