From 770d684ee974efde80186fe579ff85bc4c038b83 Mon Sep 17 00:00:00 2001
From: Volker Lendecke <vl@samba.org>
Date: Thu, 21 Nov 2013 21:05:29 +0100
Subject: [PATCH] smbd: Fix bug 10284
If we msg_read_send on a nonempty channel, we create one
tevent_immediate. If we directly receive another message and from
within the msg_read_send's tevent_req callback we immediately do
another msg_read_send, we end up with two tevent_immediate events for
msg_channel_trigger with just one incoming message. Test to follow.
This patch simplifies msg_channel.c by removing the explicit immediate
events. Instead, it relies on the implicit immediate event available
via tevent_req_defer_callback. For messages received from tdb with
a msg_read_send req pending, we directly finish that request without
putting the message on the queue.
Bug: https://bugzilla.samba.org/show_bug.cgi?id=10284
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
(cherry picked from commit 6b6920b02905661ae661a894e3bd8d2c744d7003)
---
source3/lib/msg_channel.c | 100 ++++++++++++++--------------------------------
1 file changed, 31 insertions(+), 69 deletions(-)
diff --git a/source3/lib/msg_channel.c b/source3/lib/msg_channel.c
index 625d07c..8e23fd4 100644
--- a/source3/lib/msg_channel.c
+++ b/source3/lib/msg_channel.c
@@ -41,9 +41,6 @@ static void msg_channel_init_got_ctdb(struct tevent_req *subreq);
static void msg_channel_init_got_msg(struct messaging_context *msg,
void *priv, uint32_t msg_type,
struct server_id server_id, DATA_BLOB *data);
-static void msg_channel_trigger(struct tevent_context *ev,
- struct tevent_immediate *im,
- void *priv);
static int msg_channel_destructor(struct msg_channel *s);
struct tevent_req *msg_channel_init_send(TALLOC_CTX *mem_ctx,
@@ -157,6 +154,12 @@ fail:
return err;
}
+struct msg_read_state {
+ struct tevent_context *ev;
+ struct msg_channel *channel;
+ struct messaging_rec *rec;
+};
+
static void msg_channel_init_got_msg(struct messaging_context *msg,
void *priv, uint32_t msg_type,
struct server_id server_id,
@@ -167,7 +170,6 @@ static void msg_channel_init_got_msg(struct messaging_context *msg,
struct messaging_rec *rec;
struct messaging_rec **msgs;
size_t num_msgs;
- struct tevent_immediate *im;
rec = talloc(s, struct messaging_rec);
if (rec == NULL) {
@@ -184,6 +186,19 @@ static void msg_channel_init_got_msg(struct messaging_context *msg,
}
rec->buf.length = data->length;
+ if (s->pending_req != NULL) {
+ struct tevent_req *req = s->pending_req;
+ struct msg_read_state *state = tevent_req_data(
+ req, struct msg_read_state);
+
+ s->pending_req = NULL;
+
+ state->rec = talloc_move(state, &rec);
+ tevent_req_defer_callback(req, s->ev);
+ tevent_req_done(req);
+ return;
+ }
+
num_msgs = talloc_array_length(s->msgs);
msgs = talloc_realloc(s, s->msgs, struct messaging_rec *, num_msgs+1);
if (msgs == NULL) {
@@ -192,28 +207,11 @@ static void msg_channel_init_got_msg(struct messaging_context *msg,
s->msgs = msgs;
s->msgs[num_msgs] = talloc_move(s->msgs, &rec);
- if (s->pending_req == NULL) {
- return;
- }
-
- im = tevent_create_immediate(s);
- if (im == NULL) {
- goto fail;
- }
- tevent_schedule_immediate(im, s->ev, msg_channel_trigger, s);
return;
fail:
TALLOC_FREE(rec);
}
-struct msg_read_state {
- struct tevent_context *ev;
- struct tevent_req *req;
- struct msg_channel *channel;
- struct messaging_rec *rec;
-};
-
-static int msg_read_state_destructor(struct msg_read_state *s);
static void msg_read_got_ctdb(struct tevent_req *subreq);
struct tevent_req *msg_read_send(TALLOC_CTX *mem_ctx,
@@ -221,7 +219,6 @@ struct tevent_req *msg_read_send(TALLOC_CTX *mem_ctx,
struct msg_channel *channel)
{
struct tevent_req *req;
- struct tevent_immediate *im;
struct msg_read_state *state;
void *msg_tdb_event;
size_t num_msgs;
@@ -231,28 +228,28 @@ struct tevent_req *msg_read_send(TALLOC_CTX *mem_ctx,
return NULL;
}
state->ev = ev;
- state->req = req;
state->channel = channel;
if (channel->pending_req != NULL) {
tevent_req_error(req, EBUSY);
return tevent_req_post(req, ev);
}
- channel->pending_req = req;
- channel->ev = ev;
- talloc_set_destructor(state, msg_read_state_destructor);
num_msgs = talloc_array_length(channel->msgs);
if (num_msgs != 0) {
- im = tevent_create_immediate(channel->ev);
- if (tevent_req_nomem(im, req)) {
- return tevent_req_post(req, ev);
- }
- tevent_schedule_immediate(im, channel->ev, msg_channel_trigger,
- channel);
- return req;
+ state->rec = talloc_move(state, &channel->msgs[0]);
+ memmove(channel->msgs, channel->msgs+1,
+ sizeof(struct messaging_rec *) * (num_msgs-1));
+ channel->msgs = talloc_realloc(
+ channel, channel->msgs, struct messaging_rec *,
+ num_msgs - 1);
+ tevent_req_done(req);
+ return tevent_req_post(req, ev);
}
+ channel->pending_req = req;
+ channel->ev = ev;
+
msg_tdb_event = messaging_tdb_event(state, channel->msg, ev);
if (tevent_req_nomem(msg_tdb_event, req)) {
return tevent_req_post(req, ev);
@@ -271,42 +268,6 @@ struct tevent_req *msg_read_send(TALLOC_CTX *mem_ctx,
return req;
}
-static int msg_read_state_destructor(struct msg_read_state *s)
-{
- assert(s->channel->pending_req == s->req);
- s->channel->pending_req = NULL;
- return 0;
-}
-
-static void msg_channel_trigger(struct tevent_context *ev,
- struct tevent_immediate *im,
- void *priv)
-{
- struct msg_channel *channel;
- struct tevent_req *req;
- struct msg_read_state *state;
- size_t num_msgs;
-
- channel = talloc_get_type_abort(priv, struct msg_channel);
- req = channel->pending_req;
- state = tevent_req_data(req, struct msg_read_state);
-
- talloc_set_destructor(state, NULL);
- msg_read_state_destructor(state);
-
- num_msgs = talloc_array_length(channel->msgs);
- assert(num_msgs > 0);
-
- state->rec = talloc_move(state, &channel->msgs[0]);
-
- memmove(channel->msgs, channel->msgs+1,
- sizeof(struct messaging_rec *) * (num_msgs-1));
- channel->msgs = talloc_realloc(
- channel, channel->msgs, struct messaging_rec *, num_msgs - 1);
-
- tevent_req_done(req);
-}
-
static void msg_read_got_ctdb(struct tevent_req *subreq)
{
struct tevent_req *req = tevent_req_callback_data(
@@ -368,5 +329,6 @@ int msg_read_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
return err;
}
*prec = talloc_move(mem_ctx, &state->rec);
+ tevent_req_received(req);
return 0;
}
--
1.8.1.2