git: fb901935f257 - main - socket: Split up sosend_generic()

The branch main has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=fb901935f257ddcc492fe9efb605797f181c6597

commit fb901935f257ddcc492fe9efb605797f181c6597
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2024-08-19 14:20:43 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2024-08-19 14:37:27 +0000

    socket: Split up sosend_generic()
    
    Factor out the bits that run with the sock I/O lock held into a separate
    function.  In this implementation, we are doing a bit more work under
    the I/O lock than before.  However, lock contention is only a problem
    when multiple threads are transmitting on the same socket, which is an
    unusual case that is not expected to perform well in any case.
    
    No functional change intended.
    
    Reviewed by:    gallatin, glebius
    MFC after:      2 weeks
    Sponsored by:   Klara, Inc.
    Sponsored by:   Stormshield
    Differential Revision:  https://reviews.freebsd.org/D46305
---
 sys/kern/uipc_socket.c | 47 +++++++++++++++++++++++++++++------------------
 1 file changed, 29 insertions(+), 18 deletions(-)

diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c
index e7c4a85d5970..a5e88fc7ffc6 100644
--- a/sys/kern/uipc_socket.c
+++ b/sys/kern/uipc_socket.c
@@ -1656,8 +1656,8 @@ out:
  * counts if EINTR/ERESTART are returned.  Data and control buffers are freed
  * on return.
  */
-int
-sosend_generic(struct socket *so, struct sockaddr *addr, struct uio *uio,
+static int
+sosend_generic_locked(struct socket *so, struct sockaddr *addr, struct uio *uio,
     struct mbuf *top, struct mbuf *control, int flags, struct thread *td)
 {
 	long space;
@@ -1673,6 +1673,9 @@ sosend_generic(struct socket *so, struct sockaddr *addr, struct uio *uio,
 	tls = NULL;
 	tls_rtype = TLS_RLTYPE_APP;
 #endif
+
+	SOCK_IO_SEND_ASSERT_LOCKED(so);
+
 	if (uio != NULL)
 		resid = uio->uio_resid;
 	else if ((top->m_flags & M_PKTHDR) != 0)
@@ -1702,10 +1705,6 @@ sosend_generic(struct socket *so, struct sockaddr *addr, struct uio *uio,
 	if (control != NULL)
 		clen = control->m_len;
 
-	error = SOCK_IO_SEND_LOCK(so, SBLOCKWAIT(flags));
-	if (error)
-		goto out;
-
 #ifdef KERN_TLS
 	tls_send_flag = 0;
 	tls = ktls_hold(so->so_snd.sb_tls_info);
@@ -1728,7 +1727,7 @@ sosend_generic(struct socket *so, struct sockaddr *addr, struct uio *uio,
 
 		if (resid == 0 && !ktls_permit_empty_frames(tls)) {
 			error = EINVAL;
-			goto release;
+			goto out;
 		}
 	}
 #endif
@@ -1739,13 +1738,13 @@ restart:
 		if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
 			SOCKBUF_UNLOCK(&so->so_snd);
 			error = EPIPE;
-			goto release;
+			goto out;
 		}
 		if (so->so_error) {
 			error = so->so_error;
 			so->so_error = 0;
 			SOCKBUF_UNLOCK(&so->so_snd);
-			goto release;
+			goto out;
 		}
 		if ((so->so_state & SS_ISCONNECTED) == 0) {
 			/*
@@ -1759,7 +1758,7 @@ restart:
 				if (!(resid == 0 && clen != 0)) {
 					SOCKBUF_UNLOCK(&so->so_snd);
 					error = ENOTCONN;
-					goto release;
+					goto out;
 				}
 			} else if (addr == NULL) {
 				SOCKBUF_UNLOCK(&so->so_snd);
@@ -1767,7 +1766,7 @@ restart:
 					error = ENOTCONN;
 				else
 					error = EDESTADDRREQ;
-				goto release;
+				goto out;
 			}
 		}
 		space = sbspace(&so->so_snd);
@@ -1777,7 +1776,7 @@ restart:
 		    clen > so->so_snd.sb_hiwat) {
 			SOCKBUF_UNLOCK(&so->so_snd);
 			error = EMSGSIZE;
-			goto release;
+			goto out;
 		}
 		if (space < resid + clen &&
 		    (atomic || space < so->so_snd.sb_lowat || space < clen)) {
@@ -1785,12 +1784,12 @@ restart:
 			    (flags & (MSG_NBIO | MSG_DONTWAIT)) != 0) {
 				SOCKBUF_UNLOCK(&so->so_snd);
 				error = EWOULDBLOCK;
-				goto release;
+				goto out;
 			}
 			error = sbwait(so, SO_SND);
 			SOCKBUF_UNLOCK(&so->so_snd);
 			if (error)
-				goto release;
+				goto out;
 			goto restart;
 		}
 		SOCKBUF_UNLOCK(&so->so_snd);
@@ -1835,7 +1834,7 @@ restart:
 					    ((flags & MSG_EOR) ? M_EOR : 0));
 				if (top == NULL) {
 					error = EFAULT; /* only possible error */
-					goto release;
+					goto out;
 				}
 				space -= resid - uio->uio_resid;
 				resid = uio->uio_resid;
@@ -1899,12 +1898,10 @@ restart:
 			control = NULL;
 			top = NULL;
 			if (error)
-				goto release;
+				goto out;
 		} while (resid && space > 0);
 	} while (resid);
 
-release:
-	SOCK_IO_SEND_UNLOCK(so);
 out:
 #ifdef KERN_TLS
 	if (tls != NULL)
@@ -1917,6 +1914,20 @@ out:
 	return (error);
 }
 
+int
+sosend_generic(struct socket *so, struct sockaddr *addr, struct uio *uio,
+    struct mbuf *top, struct mbuf *control, int flags, struct thread *td)
+{
+	int error;
+
+	error = SOCK_IO_SEND_LOCK(so, 0);
+	if (error)
+		return (error);
+	error = sosend_generic_locked(so, addr, uio, top, control, flags, td);
+	SOCK_IO_SEND_UNLOCK(so);
+	return (error);
+}
+
 /*
  * Send to a socket from a kernel thread.
  *