This adds support for the SIOCOUTQ IOCTL to get the send buffer fill
of a DCCP socket, like UDP and TCP sockets already have.
Regarding the used data field: DCCP uses per packet sequence numbers,
not per byte, so sequence numbers can't be used like in TCP. sk_wmem_queued
is not used by DCCP and always 0, even in test on highly congested paths.
Therefore this uses sk_wmem_alloc like in UDP.
Signed-off-by: Richard Sailer <richard_siegfried@xxxxxxxxxxxx>
---
v5: More infos into dccp.rst, +empty line after declarations
---
Documentation/networking/dccp.rst | 3 +++
net/dccp/proto.c | 9 +++++++++
2 files changed, 12 insertions(+)
diff --git a/Documentation/networking/dccp.rst b/Documentation/networking/dccp.rst
index dde16be044562..91e5c33ba3ff5 100644
--- a/Documentation/networking/dccp.rst
+++ b/Documentation/networking/dccp.rst
@@ -192,6 +192,9 @@ FIONREAD
Works as in udp(7): returns in the ``int`` argument pointer the size of
the next pending datagram in bytes, or 0 when no datagram is pending.
+SIOCOUTQ
+ Returns the number of unsent data bytes in the socket send queue as ``int``
+ into the buffer specified by the argument pointer.
Other tunables
==============
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index fd92d3fe321f0..9e453611107f1 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -375,6 +375,15 @@ int dccp_ioctl(struct sock *sk, int cmd, unsigned long arg)
goto out;
switch (cmd) {
+ case SIOCOUTQ: {
+ int amount = sk_wmem_alloc_get(sk);
+ /* Using sk_wmem_alloc here because sk_wmem_queued is not used by DCCP and
+ * always 0, comparably to UDP.
+ */
+
+ rc = put_user(amount, (int __user *)arg);
+ }
+ break;
case SIOCINQ: {
struct sk_buff *skb;
unsigned long amount = 0;
--
2.27.0
