d/freebsd-dev
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Fix r361037.

Browse Source 
Reorder flag manipulations and use barrier to ensure that the program
order is followed by compiler and CPU, for unlocked reader of so_state.

In collaboration with:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D24842
This commit is contained in:
Konstantin Belousov 2020-05-14 20:17:09 +00:00
parent 134e17798c
commit 0532a7a2df
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=361056
1 changed files with 10 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
sys/kern/uipc_socket.c
View File

@ -4016,8 +4016,17 @@ soisdisconnected(struct socket *so)
{
SOCK_LOCK(so);
so->so_state &= ~(SS_ISCONNECTING|SS_ISCONNECTED|SS_ISDISCONNECTING);
/*
* There is at least one reader of so_state that does not
* acquire socket lock, namely soreceive_generic(). Ensure
* that it never sees all flags that track connection status
* cleared, by ordering the update with a barrier semantic of
* our release thread fence.
*/
so->so_state |= SS_ISDISCONNECTED;
atomic_thread_fence_rel();
so->so_state &= ~(SS_ISCONNECTING|SS_ISCONNECTED|SS_ISDISCONNECTING);
if (!SOLISTENING(so)) {
SOCK_UNLOCK(so);