Add an interface for the user to notify the kernel that it is done reading the devmem dmabuf frags returned as cmsg. The kernel will drop the reference on the frags to make them available for reuse.
Signed-off-by: Willem de Bruijn willemb@google.com Signed-off-by: Kaiyuan Zhang kaiyuanz@google.com Signed-off-by: Mina Almasry almasrymina@google.com Reviewed-by: Pavel Begunkov asml.silence@gmail.com Reviewed-by: Eric Dumazet edumazet@google.com
---
v16: - Use sk_is_tcp(). - Fix unnamed 128 DONTNEED limit (David). - Fix kernel allocating for 128 tokens even if the user didn't ask for that much (Eric). - Fix number assignement (Arnd).
v10: - Fix leak of tokens (Nikolay).
v7: - Updated SO_DEVMEM_* uapi to use the next available entry (Arnd).
v6: - Squash in locking optimizations from edumazet@google.com. With his changes we lock the xarray once per sock_devmem_dontneed operation rather than once per frag.
Changes in v1: - devmemtoken -> dmabuf_token (David). - Use napi_pp_put_page() for refcounting (Yunsheng). - Fix build error with missing socket options on other asms.
--- arch/alpha/include/uapi/asm/socket.h | 1 + arch/mips/include/uapi/asm/socket.h | 1 + arch/parisc/include/uapi/asm/socket.h | 1 + arch/sparc/include/uapi/asm/socket.h | 1 + include/uapi/asm-generic/socket.h | 1 + include/uapi/linux/uio.h | 4 ++ net/core/sock.c | 68 +++++++++++++++++++++++++++ 7 files changed, 77 insertions(+)
diff --git a/arch/alpha/include/uapi/asm/socket.h b/arch/alpha/include/uapi/asm/socket.h index ef4656a41058a..251b73c5481ea 100644 --- a/arch/alpha/include/uapi/asm/socket.h +++ b/arch/alpha/include/uapi/asm/socket.h @@ -144,6 +144,7 @@ #define SCM_DEVMEM_LINEAR SO_DEVMEM_LINEAR #define SO_DEVMEM_DMABUF 79 #define SCM_DEVMEM_DMABUF SO_DEVMEM_DMABUF +#define SO_DEVMEM_DONTNEED 80
#if !defined(__KERNEL__)
diff --git a/arch/mips/include/uapi/asm/socket.h b/arch/mips/include/uapi/asm/socket.h index 414807d55e33f..8ab7582291abf 100644 --- a/arch/mips/include/uapi/asm/socket.h +++ b/arch/mips/include/uapi/asm/socket.h @@ -155,6 +155,7 @@ #define SCM_DEVMEM_LINEAR SO_DEVMEM_LINEAR #define SO_DEVMEM_DMABUF 79 #define SCM_DEVMEM_DMABUF SO_DEVMEM_DMABUF +#define SO_DEVMEM_DONTNEED 80
#if !defined(__KERNEL__)
diff --git a/arch/parisc/include/uapi/asm/socket.h b/arch/parisc/include/uapi/asm/socket.h index 2b817efd45444..38fc0b188e084 100644 --- a/arch/parisc/include/uapi/asm/socket.h +++ b/arch/parisc/include/uapi/asm/socket.h @@ -136,6 +136,7 @@ #define SCM_DEVMEM_LINEAR SO_DEVMEM_LINEAR #define SO_DEVMEM_DMABUF 79 #define SCM_DEVMEM_DMABUF SO_DEVMEM_DMABUF +#define SO_DEVMEM_DONTNEED 80
#if !defined(__KERNEL__)
diff --git a/arch/sparc/include/uapi/asm/socket.h b/arch/sparc/include/uapi/asm/socket.h index 00248fc689773..57084ed2f3c4e 100644 --- a/arch/sparc/include/uapi/asm/socket.h +++ b/arch/sparc/include/uapi/asm/socket.h @@ -137,6 +137,7 @@ #define SCM_DEVMEM_LINEAR SO_DEVMEM_LINEAR #define SO_DEVMEM_DMABUF 0x0058 #define SCM_DEVMEM_DMABUF SO_DEVMEM_DMABUF +#define SO_DEVMEM_DONTNEED 0x0059
#if !defined(__KERNEL__)
diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h index e993edc9c0ee6..3b4e3e8156025 100644 --- a/include/uapi/asm-generic/socket.h +++ b/include/uapi/asm-generic/socket.h @@ -139,6 +139,7 @@ #define SCM_DEVMEM_LINEAR SO_DEVMEM_LINEAR #define SO_DEVMEM_DMABUF 79 #define SCM_DEVMEM_DMABUF SO_DEVMEM_DMABUF +#define SO_DEVMEM_DONTNEED 80
#if !defined(__KERNEL__)
diff --git a/include/uapi/linux/uio.h b/include/uapi/linux/uio.h index 3a22ddae376a2..d17f8fcd93ec9 100644 --- a/include/uapi/linux/uio.h +++ b/include/uapi/linux/uio.h @@ -33,6 +33,10 @@ struct dmabuf_cmsg { */ };
+struct dmabuf_token { + __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 9abc4fe259535..df2a2dd6409da 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -124,6 +124,7 @@ #include <linux/netdevice.h> #include <net/protocol.h> #include <linux/skbuff.h> +#include <linux/skbuff_ref.h> #include <net/net_namespace.h> #include <net/request_sock.h> #include <net/sock.h> @@ -1049,6 +1050,69 @@ static int sock_reserve_memory(struct sock *sk, int bytes) return 0; }
+#ifdef CONFIG_PAGE_POOL + +/* This is the number of tokens that the user can SO_DEVMEM_DONTNEED in + * 1 syscall. The limit exists to limit the amount of memory the kernel + * allocates to copy these tokens. + */ +#define MAX_DONTNEED_TOKENS 128 + +static noinline_for_stack int +sock_devmem_dontneed(struct sock *sk, sockptr_t optval, unsigned int optlen) +{ + unsigned int num_tokens, i, j, k, netmem_num = 0; + struct dmabuf_token *tokens; + netmem_ref netmems[16]; + int ret = 0; + + if (!sk_is_tcp(sk)) + return -EBADF; + + if (optlen % sizeof(struct dmabuf_token) || + optlen > sizeof(*tokens) * MAX_DONTNEED_TOKENS) + return -EINVAL; + + tokens = kvmalloc_array(optlen, sizeof(*tokens), GFP_KERNEL); + if (!tokens) + return -ENOMEM; + + num_tokens = optlen / sizeof(struct dmabuf_token); + if (copy_from_sockptr(tokens, optval, optlen)) { + kvfree(tokens); + return -EFAULT; + } + + xa_lock_bh(&sk->sk_user_frags); + for (i = 0; i < num_tokens; i++) { + for (j = 0; j < tokens[i].token_count; j++) { + netmem_ref netmem = (__force netmem_ref)__xa_erase( + &sk->sk_user_frags, tokens[i].token_start + j); + + if (netmem && + !WARN_ON_ONCE(!netmem_is_net_iov(netmem))) { + netmems[netmem_num++] = netmem; + if (netmem_num == ARRAY_SIZE(netmems)) { + xa_unlock_bh(&sk->sk_user_frags); + for (k = 0; k < netmem_num; k++) + WARN_ON_ONCE(!napi_pp_put_page(netmems[k])); + netmem_num = 0; + xa_lock_bh(&sk->sk_user_frags); + } + ret++; + } + } + } + + xa_unlock_bh(&sk->sk_user_frags); + for (k = 0; k < netmem_num; k++) + WARN_ON_ONCE(!napi_pp_put_page(netmems[k])); + + kvfree(tokens); + return ret; +} +#endif + void sockopt_lock_sock(struct sock *sk) { /* When current->bpf_ctx is set, the setsockopt is called from @@ -1211,6 +1275,10 @@ int sk_setsockopt(struct sock *sk, int level, int optname, ret = -EOPNOTSUPP; return ret; } +#ifdef CONFIG_PAGE_POOL + case SO_DEVMEM_DONTNEED: + return sock_devmem_dontneed(sk, optval, optlen); +#endif }
sockopt_lock_sock(sk);