BUG/MINOR: map/cli: make sure patterns don't vanish under "show map"'s init
When "show map" initializes itself, it first takes the reference to the
starting point under a lock, then releases it before switching to state
STATE_LIST, and takes the lock again. The problem is that it is possible
for another thread to remove the first element during this unlock/lock
sequence, and make the list run anywhere. This is of course extremely
unlikely but not impossible.
Let's initialize the pointer in the STATE_LIST part under the same lock,
which is simpler and more reliable.
This should be backported to all versions.
(cherry picked from commit 1ae0c43244254a3cf652300413625191d6a9dd4f)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 33f525cfcb7429443e8ac5e7ff338b22dfb2d34d)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/src/map.c b/src/map.c
index 2da22e9..f482b77 100644
--- a/src/map.c
+++ b/src/map.c
@@ -344,27 +344,17 @@
switch (appctx->st2) {
case STAT_ST_INIT:
- /* the function had not been called yet, let's prepare the
- * buffer for a response. We initialize the current stream
- * pointer to the first in the global list. When a target
- * stream is being destroyed, it is responsible for updating
- * this pointer. We know we have reached the end when this
- * pointer points back to the head of the streams list.
- */
- HA_SPIN_LOCK(PATREF_LOCK, &appctx->ctx.map.ref->lock);
- LIST_INIT(&appctx->ctx.map.bref.users);
- appctx->ctx.map.bref.ref = appctx->ctx.map.ref->head.n;
- HA_SPIN_UNLOCK(PATREF_LOCK, &appctx->ctx.map.ref->lock);
appctx->st2 = STAT_ST_LIST;
/* fall through */
case STAT_ST_LIST:
-
HA_SPIN_LOCK(PATREF_LOCK, &appctx->ctx.map.ref->lock);
if (!LIST_ISEMPTY(&appctx->ctx.map.bref.users)) {
LIST_DELETE(&appctx->ctx.map.bref.users);
LIST_INIT(&appctx->ctx.map.bref.users);
+ } else {
+ appctx->ctx.map.bref.ref = appctx->ctx.map.ref->head.n;
}
while (appctx->ctx.map.bref.ref != &appctx->ctx.map.ref->head) {
@@ -716,6 +706,7 @@
else
appctx->ctx.cli.i0 = appctx->ctx.map.ref->curr_gen;
+ LIST_INIT(&appctx->ctx.map.bref.users);
appctx->io_handler = cli_io_handler_pat_list;
appctx->io_release = cli_release_show_map;
return 0;