Date: Fri, 10 Sep 2021 21:27:58 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 74a68313b503 - main - socket: Add macros to lock socket buffers using socket references Message-ID: <202109102127.18ALRwOV020665@gitrepo.freebsd.org>
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The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=74a68313b503940158a2e8e8f02626d7cdbdaff9 commit 74a68313b503940158a2e8e8f02626d7cdbdaff9 Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2021-09-10 21:20:39 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2021-09-10 21:20:39 +0000 socket: Add macros to lock socket buffers using socket references Since commit c67f3b8b78e50c6df7c057d6cf108e4d6b4312d0 the sockbuf mutexes belong to the containing socket. Sockbufs contain a pointer to a mutex, which by default is initialized to the corresponding mutexes in the socket. The SOCKBUF_LOCK() etc. macros operate on this pointer. However, the pointer is clobbered by listen(2) so it's not safe to use them unless one is sure that the socket is not a listening socket. This change introduces a new set of macros which lock socket buffers through the socket. This is a bit cheaper since it removes the pointer indirection, and allows one to safely lock socket buffers and then check for a listening socket. For MFC, these macros should be reimplemented in terms of the existing socket buffer layout. Reviewed by: tuexen, gallatin, jhb Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D31900 --- sys/sys/sockbuf.h | 7 +++++-- sys/sys/socketvar.h | 30 ++++++++++++++++++++++++++++-- 2 files changed, 33 insertions(+), 4 deletions(-) diff --git a/sys/sys/sockbuf.h b/sys/sys/sockbuf.h index 3b345870bd5f..3fc9b10cd240 100644 --- a/sys/sys/sockbuf.h +++ b/sys/sys/sockbuf.h @@ -118,8 +118,11 @@ struct sockbuf { #ifdef _KERNEL /* - * Per-socket buffer mutex used to protect most fields in the socket - * buffer. + * Per-socket buffer mutex used to protect most fields in the socket buffer. + * These make use of the mutex pointer embedded in struct sockbuf, which + * currently just references mutexes in the containing socket. The + * SOCK_SENDBUF_LOCK() etc. macros can be used instead of or in combination with + * these locking macros. */ #define SOCKBUF_MTX(_sb) ((_sb)->sb_mtx) #define SOCKBUF_LOCK_INIT(_sb, _name) \ diff --git a/sys/sys/socketvar.h b/sys/sys/socketvar.h index 69dd1706e366..57913f7bbd65 100644 --- a/sys/sys/socketvar.h +++ b/sys/sys/socketvar.h @@ -77,8 +77,8 @@ enum socket_qstate { * Locking key to struct socket: * (a) constant after allocation, no locking required. * (b) locked by SOCK_LOCK(so). - * (cr) locked by SOCKBUF_LOCK(&so->so_rcv). - * (cs) locked by SOCKBUF_LOCK(&so->so_snd). + * (cr) locked by SOCK_RECVBUF_LOCK(so)/SOCKBUF_LOCK(&so->so_rcv). + * (cs) locked by SOCK_SENDBUF_LOCK(so)/SOCKBUF_LOCK(&so->so_snd). * (e) locked by SOLISTEN_LOCK() of corresponding listening socket. * (f) not locked since integer reads/writes are atomic. * (g) used only as a sleep/wakeup address, no value. @@ -255,6 +255,32 @@ struct socket { ("%s: %p not listening", __func__, (sol))); \ } while (0) +/* + * Socket buffer locks. These manipulate the same mutexes as SOCKBUF_LOCK() + * and related macros. + */ +#define SOCK_RECVBUF_MTX(so) \ + (&(so)->so_rcv_mtx) +#define SOCK_RECVBUF_LOCK(so) \ + mtx_lock(SOCK_RECVBUF_MTX(so)) +#define SOCK_RECVBUF_UNLOCK(so) \ + mtx_unlock(SOCK_RECVBUF_MTX(so)) +#define SOCK_RECVBUF_LOCK_ASSERT(so) \ + mtx_assert(SOCK_RECVBUF_MTX(so), MA_OWNED) +#define SOCK_RECVBUF_UNLOCK_ASSERT(so) \ + mtx_assert(SOCK_RECVBUF_MTX(so), MA_NOTOWNED) + +#define SOCK_SENDBUF_MTX(so) \ + (&(so)->so_snd_mtx) +#define SOCK_SENDBUF_LOCK(so) \ + mtx_lock(SOCK_SENDBUF_MTX(so)) +#define SOCK_SENDBUF_UNLOCK(so) \ + mtx_unlock(SOCK_SENDBUF_MTX(so)) +#define SOCK_SENDBUF_LOCK_ASSERT(so) \ + mtx_assert(SOCK_SENDBUF_MTX(so), MA_OWNED) +#define SOCK_SENDBUF_UNLOCK_ASSERT(so) \ + mtx_assert(SOCK_SENDBUF_MTX(so), MA_NOTOWNED) + /* * Macros for sockets and socket buffering. */
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