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@google.com --- 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;