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s4/messaging: messaging_dgm_ref talloc hierarchy fix

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Ensure the messaging dgm context goes away *before* the tevent
context. The messaging dgm context will likely have active fd or timer
events, their rundown will touch the associated tevent context.

Otoh, I deliberately don't free the imessaging context here, that's going
to happen as part of freeing the talloc_autofree_context() as before. I
think it suffers the same problem, eg imessaging_deregister() works on
an imessaging_context that might already be freed. But as it works,
don't change it.

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
This commit is contained in:
Ralph Boehme 2016-09-09 07:12:11 +02:00 committed by Jeremy Allison
parent b3cf15e530
commit cfce21281a
3 changed files with 38 additions and 0 deletions
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29
source4/lib/messaging/messaging.c
View File

@ -293,6 +293,31 @@ static void imessaging_dgm_recv(const uint8_t *buf, size_t buf_len,
int *fds, size_t num_fds,
void *private_data);
/* Keep a list of imessaging contexts */
static struct imessaging_context *msg_ctxs;
static int imessaging_context_destructor(struct imessaging_context *msg)
{
DLIST_REMOVE(msg_ctxs, msg);
return 0;
}
/*
* Cleanup messaging dgm contexts
*
* We must make sure to unref all messaging_dgm_ref's *before* the
* tevent context goes away. Only when the last ref is freed, the
* refcounted messaging dgm context will be freed.
*/
void imessaging_dgm_unref_all(void)
{
struct imessaging_context *msg = NULL;
for (msg = msg_ctxs; msg != NULL; msg = msg->next) {
TALLOC_FREE(msg->msg_dgm_ref);
}
}
/*
create the listening socket and setup the dispatcher
*/
@ -316,6 +341,8 @@ struct imessaging_context *imessaging_init(TALLOC_CTX *mem_ctx,
return NULL;
}
talloc_set_destructor(msg, imessaging_context_destructor);
/* create the messaging directory if needed */
lock_dir = lpcfg_lock_directory(lp_ctx);
@ -374,6 +401,8 @@ struct imessaging_context *imessaging_init(TALLOC_CTX *mem_ctx,
imessaging_register(msg, NULL, MSG_IRPC, irpc_handler);
IRPC_REGISTER(msg, irpc, IRPC_UPTIME, irpc_uptime, msg);
DLIST_ADD(msg_ctxs, msg);
return msg;
fail:
talloc_free(msg);

1
source4/lib/messaging/messaging.h
View File

@ -44,6 +44,7 @@ struct imessaging_context *imessaging_init(TALLOC_CTX *mem_ctx,
struct loadparm_context *lp_ctx,
struct server_id server_id,
struct tevent_context *ev);
void imessaging_dgm_unref_all(void);
int imessaging_cleanup(struct imessaging_context *msg);
struct imessaging_context *imessaging_client_init(TALLOC_CTX *mem_ctx,
struct loadparm_context *lp_ctx,

8
source4/smbd/server.c
View File

@ -284,6 +284,12 @@ static void show_build(void)
exit(0);
}
static int event_ctx_destructor(struct tevent_context *event_ctx)
{
imessaging_dgm_unref_all();
return 0;
}
/*
main server.
*/
@ -422,6 +428,8 @@ static int binary_smbd_main(const char *binary_name, int argc, const char *argv[
exit_daemon("Initializing event context failed", EACCES);
}
talloc_set_destructor(event_ctx, event_ctx_destructor);
if (opt_interactive) {
/* terminate when stdin goes away */
stdin_event_flags = TEVENT_FD_READ;