net: airoha: Fix schedule while atomic in airoha_ppe_deinit()

airoha_ppe_deinit() runs airoha_npu_ppe_deinit() in atomic context.
airoha_npu_ppe_deinit routine allocates ppe_data buffer with GFP_KERNEL
flag. Rely on rcu_replace_pointer in airoha_ppe_deinit routine in order
to fix schedule while atomic issue in airoha_npu_ppe_deinit() since we
do not need atomic context there.

Fixes: 00a7678 ("net: airoha: Introduce flowtable offload support")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20260105-airoha-fw-ethtool-v2-1-3b32b158cc31@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: LorenzoBianconi

drivers/net/ethernet/airoha/airoha_ppe.c

@@ -1547,13 +1547,16 @@ void airoha_ppe_deinit(struct airoha_eth *eth)
 {
 	struct airoha_npu *npu;
 
-	rcu_read_lock();
-	npu = rcu_dereference(eth->npu);
+	mutex_lock(&flow_offload_mutex);
+
+	npu = rcu_replace_pointer(eth->npu, NULL,
+				  lockdep_is_held(&flow_offload_mutex));
 	if (npu) {
 		npu->ops.ppe_deinit(npu);
 		airoha_npu_put(npu);
 	}
-	rcu_read_unlock();
+
+	mutex_unlock(&flow_offload_mutex);
 
 	rhashtable_destroy(&eth->ppe->l2_flows);
 	rhashtable_destroy(&eth->flow_table);