mirror/freebsd
1
0
Fork 0
mirror of https://git.FreeBSD.org/src.git synced 2024-10-19 02:29:40 +00:00
Code Issues Releases Activity

Atomically update the global gMsgId in libnetgraph.

Browse Source 
Otherwise concurrently running threads may inadvertently use the same
token for different messages.

Preserve the behaviour of disallowing negative message tokens, but allow
a message token value of zero since this simplifies the code a bit and
tokens are documented to be non-negative.

PR:		234442
Reported and tested by:	eugen
MFC after:	1 month
Sponsored by:	The FreeBSD Foundation
This commit is contained in:
Mark Johnston 2019-05-10 16:43:47 +00:00
parent 0f78871d44
commit 7f75bbd066
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=347439
1 changed files with 4 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
lib/libnetgraph/msg.c
View File

@ -44,6 +44,7 @@ __FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/socket.h>
#include <stdarg.h>
#include <stdatomic.h>
#include <netgraph/ng_message.h>
#include <netgraph/ng_socket.h>
@ -51,7 +52,7 @@ __FBSDID("$FreeBSD$");
#include "internal.h"
/* Next message token value */
static int gMsgId;
static _Atomic(unsigned int) gMsgId;
/* For delivering both messages and replies */
static int NgDeliverMsg(int cs, const char *path,
@ -72,9 +73,7 @@ NgSendMsg(int cs, const char *path,
memset(&msg, 0, sizeof(msg));
msg.header.version = NG_VERSION;
msg.header.typecookie = cookie;
if (++gMsgId < 0)
gMsgId = 1;
msg.header.token = gMsgId;
msg.header.token = atomic_fetch_add(&gMsgId, 1) & INT_MAX;
msg.header.flags = NGF_ORIG;
msg.header.cmd = cmd;
snprintf((char *)msg.header.cmdstr, NG_CMDSTRSIZ, "cmd%d", cmd);
@ -143,9 +142,7 @@ NgSendAsciiMsg(int cs, const char *path, const char *fmt, ...)
/* Now send binary version */
binary = (struct ng_mesg *)reply->data;
if (++gMsgId < 0)
gMsgId = 1;
binary->header.token = gMsgId;
binary->header.token = atomic_fetch_add(&gMsgId, 1) & INT_MAX;
binary->header.version = NG_VERSION;
if (NgDeliverMsg(cs,
path, binary, binary->data, binary->header.arglen) < 0) {