core: rmnet: Fastforward to 4.19 tip

This brings the RmNet and DFC modules up to date with the 4.19 tip as of
commit 9b38611ea527 ("rmnet: Reduce synchronize_rcu calls").

As part of this, the rmnet_ctl driver was also incorporated, using commit
4ceee3aafb7d ("rmnet_ctl: Add IPC logging and optimizations")

Change-Id: Ic45d46074c7401dfed408c769cfb6462dac0d4ee
Signed-off-by: Sean Tranchetti <stranche@codeaurora.org>

core/rmnet_ctl_client.c

@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2019-2020, The Linux Foundation. All rights reserved.
+ *
+ * RMNET_CTL client handlers
+ *
+ */
+
+#include <linux/debugfs.h>
+#include <linux/ipc_logging.h>
+#include "rmnet_ctl.h"
+#include "rmnet_ctl_client.h"
+
+#define RMNET_CTL_LOG_PAGE 10
+#define RMNET_CTL_LOG_NAME "rmnet_ctl"
+#define RMNET_CTL_LOG_LVL  "ipc_log_lvl"
+
+struct rmnet_ctl_client {
+	struct rmnet_ctl_client_hooks hooks;
+};
+
+struct rmnet_ctl_endpoint {
+	struct rmnet_ctl_dev __rcu *dev;
+	struct rmnet_ctl_client __rcu *client;
+	struct dentry *dbgfs_dir;
+	struct dentry *dbgfs_loglvl;
+	void *ipc_log;
+};
+
+#ifdef CONFIG_RMNET_CTL_DEBUG
+static u8 ipc_log_lvl = RMNET_CTL_LOG_DEBUG;
+#else
+static u8 ipc_log_lvl = RMNET_CTL_LOG_ERR;
+#endif
+
+static DEFINE_SPINLOCK(client_lock);
+static struct rmnet_ctl_endpoint ctl_ep;
+
+void rmnet_ctl_endpoint_setdev(const struct rmnet_ctl_dev *dev)
+{
+	rcu_assign_pointer(ctl_ep.dev, dev);
+
+	if (dev) {
+		ctl_ep.dbgfs_dir = debugfs_create_dir(
+					RMNET_CTL_LOG_NAME, NULL);
+		if (!IS_ERR_OR_NULL(ctl_ep.dbgfs_dir))
+			ctl_ep.dbgfs_loglvl = debugfs_create_u8(
+				RMNET_CTL_LOG_LVL, 0644, ctl_ep.dbgfs_dir,
+				&ipc_log_lvl);
+
+		if (!ctl_ep.ipc_log)
+			ctl_ep.ipc_log = ipc_log_context_create(
+				RMNET_CTL_LOG_PAGE, RMNET_CTL_LOG_NAME, 0);
+	} else {
+		debugfs_remove_recursive(ctl_ep.dbgfs_dir);
+	}
+}
+
+void rmnet_ctl_endpoint_post(const void *data, size_t len)
+{
+	struct rmnet_ctl_client *client;
+	struct sk_buff *skb;
+
+	if (unlikely(!data || !len))
+		return;
+
+	rmnet_ctl_log_info("RX", data, len);
+
+	rcu_read_lock();
+
+	client = rcu_dereference(ctl_ep.client);
+
+	if (client && client->hooks.ctl_dl_client_hook) {
+		skb = alloc_skb(len, GFP_ATOMIC);
+		if (skb) {
+			skb_put_data(skb, data, len);
+			skb->protocol = htons(ETH_P_MAP);
+			client->hooks.ctl_dl_client_hook(skb);
+		}
+	}
+
+	rcu_read_unlock();
+}
+
+void *rmnet_ctl_register_client(struct rmnet_ctl_client_hooks *hook)
+{
+	struct rmnet_ctl_client *client;
+
+	if (!hook)
+		return NULL;
+
+	client = kzalloc(sizeof(*client), GFP_KERNEL);
+	if (!client)
+		return NULL;
+	client->hooks = *hook;
+
+	spin_lock(&client_lock);
+
+	/* Only support one client for now */
+	if (rcu_dereference(ctl_ep.client)) {
+		spin_unlock(&client_lock);
+		kfree(client);
+		return NULL;
+	}
+
+	rcu_assign_pointer(ctl_ep.client, client);
+
+	spin_unlock(&client_lock);
+
+	return client;
+}
+EXPORT_SYMBOL(rmnet_ctl_register_client);
+
+int rmnet_ctl_unregister_client(void *handle)
+{
+	struct rmnet_ctl_client *client = (struct rmnet_ctl_client *)handle;
+
+	spin_lock(&client_lock);
+
+	if (rcu_dereference(ctl_ep.client) != client) {
+		spin_unlock(&client_lock);
+		return -EINVAL;
+	}
+
+	RCU_INIT_POINTER(ctl_ep.client, NULL);
+
+	spin_unlock(&client_lock);
+
+	synchronize_rcu();
+	kfree(client);
+
+	return 0;
+}
+EXPORT_SYMBOL(rmnet_ctl_unregister_client);
+
+int rmnet_ctl_send_client(void *handle, struct sk_buff *skb)
+{
+	struct rmnet_ctl_client *client = (struct rmnet_ctl_client *)handle;
+	struct rmnet_ctl_dev *dev;
+	int rc = -EINVAL;
+
+	if (client != rcu_dereference(ctl_ep.client))
+		return rc;
+
+	rmnet_ctl_log_info("TX", skb->data, skb->len);
+
+	rcu_read_lock();
+
+	dev = rcu_dereference(ctl_ep.dev);
+	if (dev && dev->xmit)
+		rc = dev->xmit(dev, skb);
+
+	rcu_read_unlock();
+
+	if (rc)
+		rmnet_ctl_log_err("TXE", rc, skb->data, skb->len);
+
+	return rc;
+}
+EXPORT_SYMBOL(rmnet_ctl_send_client);
+
+void rmnet_ctl_log(enum rmnet_ctl_log_lvl lvl, const char *msg,
+		   int rc, const void *data, unsigned int len)
+{
+	if (lvl <= ipc_log_lvl && ctl_ep.ipc_log) {
+		if (data == NULL || len == 0)
+			ipc_log_string(ctl_ep.ipc_log, "%3s(%d): (null)\n",
+				       msg, rc);
+		else
+			ipc_log_string(ctl_ep.ipc_log, "%3s(%d): %*ph\n",
+				       msg, rc, len > 32 ? 32 : len, data);
+	}
+}
+EXPORT_SYMBOL(rmnet_ctl_log);