Add an interface for the user to notify the kernel that it is done reading
the NET_RX dmabuf pages returned as cmsg. The kernel will drop the
reference on the NET_RX pages to make them available for re-use.
Signed-off-by: Mina Almasry <almasrymina@xxxxxxxxxx>
---
include/uapi/asm-generic/socket.h | 1 +
include/uapi/linux/uio.h | 4 +++
net/core/sock.c | 41 +++++++++++++++++++++++++++++++
3 files changed, 46 insertions(+)
diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
index 88f9234f78cb..2a5a7f5da358 100644
--- a/include/uapi/asm-generic/socket.h
+++ b/include/uapi/asm-generic/socket.h
@@ -132,6 +132,7 @@
#define SO_RCVMARK 75
+#define SO_DEVMEM_DONTNEED 97
#define SO_DEVMEM_HEADER 98
#define SCM_DEVMEM_HEADER SO_DEVMEM_HEADER
#define SO_DEVMEM_OFFSET 99
diff --git a/include/uapi/linux/uio.h b/include/uapi/linux/uio.h
index 8b0be0f50838..faaa765fd5a4 100644
--- a/include/uapi/linux/uio.h
+++ b/include/uapi/linux/uio.h
@@ -26,6 +26,10 @@ struct cmsg_devmem {
__u32 frag_token;
};
+struct devmemtoken {
+ __u32 token_start;
+ __u32 token_count;
+};
/*
* UIO_MAXIOV shall be at least 16 1003.1g (5.4.1.1)
*/
diff --git a/net/core/sock.c b/net/core/sock.c
index 24f2761bdb1d..f9b9d9ec7322 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1531,7 +1531,48 @@ int sk_setsockopt(struct sock *sk, int level, int optname,
/* Paired with READ_ONCE() in tcp_rtx_synack() */
WRITE_ONCE(sk->sk_txrehash, (u8)val);
break;
+ case SO_DEVMEM_DONTNEED: {
+ struct devmemtoken tokens[128];
+ unsigned int num_tokens, i, j;
+ if (sk->sk_type != SOCK_STREAM ||
+ sk->sk_protocol != IPPROTO_TCP) {
+ ret = -EBADF;
+ break;
+ }
+
+ if (optlen % sizeof(struct devmemtoken) ||
+ optlen > sizeof(tokens)) {
+ ret = -EINVAL;
+ break;
+ }
+
+ num_tokens = optlen / sizeof(struct devmemtoken);
+ if (copy_from_sockptr(tokens, optval, optlen)) {
+ ret = -EFAULT;
+ break;
+ }
+
+ ret = 0;
+
+ for (i = 0; i < num_tokens; i++) {
+ for (j = 0; j < tokens[i].token_count; j++) {
+ struct page *pg = xa_erase(&sk->sk_pagepool,
+ tokens[i].token_start + j);
+
+ if (pg)
+ put_page(pg);
+ else
+ /* -EINTR here notifies the userspace
+ * that not all tokens passed to it have
+ * been freed.
+ */
+ ret = -EINTR;
+ }
+ }
+
+ break;
+ }
default:
ret = -ENOPROTOOPT;
break;
--
2.41.0.390.g38632f3daf-goog
