Extend coverage of SOCK_LOCK(so) to include so_count, the socket

reference count:

- Assert SOCK_LOCK(so) macros that directly manipulate so_count:
  soref(), sorele().

- Assert SOCK_LOCK(so) in macros/functions that rely on the state of
  so_count: sofree(), sotryfree().

- Acquire SOCK_LOCK(so) before calling these functions or macros in
  various contexts in the stack, both at the socket and protocol
  layers.

- In some cases, perform soisdisconnected() before sotryfree(), as
  this could result in frobbing of a non-present socket if
  sotryfree() actually frees the socket.

- Note that sofree()/sotryfree() will release the socket lock even if
  they don't free the socket.

Submitted by:	sam
Sponsored by:	FreeBSD Foundation
Obtained from:	BSD/OS

1 files changed, 1 insertions, 0 deletions

diff --git a/sys/netipx/ipx_pcb.c b/sys/netipx/ipx_pcb.c
index f4f42f60ae10..2be7e1df92c4 100644
--- a/sys/netipx/ipx_pcb.c
+++ b/sys/netipx/ipx_pcb.c
@@ -268,6 +268,7 @@ ipx_pcbdetach(ipxp)
 {
 	struct socket *so = ipxp->ipxp_socket;
 
+	SOCK_LOCK(so);
 	so->so_pcb = 0;
 	sotryfree(so);
 	if (ipxp->ipxp_route.ro_rt != NULL)