ppp: Add ppp_dev_name() exported function

ppp_dev_name() gives PPP users visibility of a ppp channel's device
name. This can be used by L2TP drivers to dump the assigned PPP
interface name.

Signed-off-by: James Chapman <jchapman@katalix.com>
Reviewed-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 22 insertions, 0 deletions

diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c
index 6d61602208c1..8a0dd8a843a9 100644
--- a/drivers/net/ppp_generic.c
+++ b/drivers/net/ppp_generic.c
@@ -2163,6 +2163,24 @@ int ppp_unit_number(struct ppp_channel *chan)
 }
 
 /*
+ * Return the PPP device interface name of a channel.
+ */
+char *ppp_dev_name(struct ppp_channel *chan)
+{
+        struct channel *pch = chan->ppp;
+        char *name = NULL;
+
+        if (pch) {
+                read_lock_bh(&pch->upl);
+                if (pch->ppp && pch->ppp->dev)
+                        name = pch->ppp->dev->name;
+                read_unlock_bh(&pch->upl);
+        }
+        return name;
+}
+
+
+/*
  * Disconnect a channel from the generic layer.
  * This must be called in process context.
  */
@@ -2890,6 +2908,7 @@ EXPORT_SYMBOL(ppp_register_channel);
 EXPORT_SYMBOL(ppp_unregister_channel);
 EXPORT_SYMBOL(ppp_channel_index);
 EXPORT_SYMBOL(ppp_unit_number);
+EXPORT_SYMBOL(ppp_dev_name);
 EXPORT_SYMBOL(ppp_input);
 EXPORT_SYMBOL(ppp_input_error);
 EXPORT_SYMBOL(ppp_output_wakeup);
diff --git a/include/linux/ppp_channel.h b/include/linux/ppp_channel.h
index 0d3fa63e90ea..bff98ec1bfed 100644
--- a/include/linux/ppp_channel.h
+++ b/include/linux/ppp_channel.h
@@ -72,6 +72,9 @@ extern int ppp_channel_index(struct ppp_channel *);
 /* Get the unit number associated with a channel, or -1 if none */
 extern int ppp_unit_number(struct ppp_channel *);
 
+/* Get the device name associated with a channel, or NULL if none */
+extern char *ppp_dev_name(struct ppp_channel *);
+
 /*
  * SMP locking notes:
  * The channel code must ensure that when it calls ppp_unregister_channel,