From: Stefan Metzmacher <metze@samba.org>
Date: Sun, 28 Aug 2022 09:41:46 +0000 (+0200)
Subject: s3:g_lock: add g_lock_ctx->busy and assert it to false
X-Git-Tag: talloc-2.4.0~853
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=d19fa657d725e887ec0cd2f19b479e827230faa6;p=thirdparty%2Fsamba.git

s3:g_lock: add g_lock_ctx->busy and assert it to false

This prepares some helper functions in order to
allow callers of g_lock_lock() to pass in a callback function
that will run under the tdb chainlock when G_LOCK_WRITE was granted.

The idea is that the callers callback function would run with
g_lock_ctx->busy == true and all key based function are not be allowed
during the execution of the callback function. Only the
g_lock_lock_cb_state based helper function are allowed to be used.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
---

diff --git a/source3/lib/g_lock.c b/source3/lib/g_lock.c
index 28b1dd8382c..ec10e5b8514 100644
--- a/source3/lib/g_lock.c
+++ b/source3/lib/g_lock.c
@@ -37,6 +37,7 @@ struct g_lock_ctx {
 	struct db_context *db;
 	struct messaging_context *msg;
 	enum dbwrap_lock_order lock_order;
+	bool busy;
 };
 
 struct g_lock {
@@ -198,7 +199,7 @@ struct g_lock_ctx *g_lock_ctx_init_backend(
 {
 	struct g_lock_ctx *result;
 
-	result = talloc(mem_ctx, struct g_lock_ctx);
+	result = talloc_zero(mem_ctx, struct g_lock_ctx);
 	if (result == NULL) {
 		return NULL;
 	}
@@ -938,6 +939,8 @@ struct tevent_req *g_lock_lock_send(TALLOC_CTX *mem_ctx,
 	NTSTATUS status;
 	bool ok;
 
+	SMB_ASSERT(!ctx->busy);
+
 	req = tevent_req_create(mem_ctx, &state, struct g_lock_lock_state);
 	if (req == NULL) {
 		return NULL;
@@ -1134,6 +1137,8 @@ NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, TDB_DATA key,
 	struct timeval end;
 	NTSTATUS status;
 
+	SMB_ASSERT(!ctx->busy);
+
 	if ((type == G_LOCK_READ) || (type == G_LOCK_WRITE)) {
 		/*
 		 * This is an abstraction violation: Normally we do
@@ -1291,6 +1296,8 @@ NTSTATUS g_lock_unlock(struct g_lock_ctx *ctx, TDB_DATA key)
 	};
 	NTSTATUS status;
 
+	SMB_ASSERT(!ctx->busy);
+
 	status = dbwrap_do_locked(ctx->db, key, g_lock_unlock_fn, &state);
 	if (!NT_STATUS_IS_OK(status)) {
 		DBG_WARNING("dbwrap_do_locked failed: %s\n",
@@ -1390,6 +1397,8 @@ NTSTATUS g_lock_writev_data(
 	};
 	NTSTATUS status;
 
+	SMB_ASSERT(!ctx->busy);
+
 	status = dbwrap_do_locked(
 		ctx->db, key, g_lock_writev_data_fn, &state);
 	if (!NT_STATUS_IS_OK(status)) {
@@ -1438,6 +1447,8 @@ int g_lock_locks(struct g_lock_ctx *ctx,
 	NTSTATUS status;
 	int count;
 
+	SMB_ASSERT(!ctx->busy);
+
 	state.fn = fn;
 	state.private_data = private_data;
 
@@ -1522,6 +1533,8 @@ NTSTATUS g_lock_dump(struct g_lock_ctx *ctx, TDB_DATA key,
 	};
 	NTSTATUS status;
 
+	SMB_ASSERT(!ctx->busy);
+
 	status = dbwrap_parse_record(ctx->db, key, g_lock_dump_fn, &state);
 	if (!NT_STATUS_IS_OK(status)) {
 		DBG_DEBUG("dbwrap_parse_record returned %s\n",
@@ -1554,6 +1567,8 @@ struct tevent_req *g_lock_dump_send(
 	struct tevent_req *req = NULL, *subreq = NULL;
 	struct g_lock_dump_state *state = NULL;
 
+	SMB_ASSERT(!ctx->busy);
+
 	req = tevent_req_create(mem_ctx, &state, struct g_lock_dump_state);
 	if (req == NULL) {
 		return NULL;
@@ -1563,6 +1578,8 @@ struct tevent_req *g_lock_dump_send(
 	state->fn = fn;
 	state->private_data = private_data;
 
+	SMB_ASSERT(!ctx->busy);
+
 	subreq = dbwrap_parse_record_send(
 		state,
 		ev,
@@ -1664,6 +1681,8 @@ struct tevent_req *g_lock_watch_data_send(
 	struct g_lock_watch_data_state *state = NULL;
 	NTSTATUS status;
 
+	SMB_ASSERT(!ctx->busy);
+
 	req = tevent_req_create(
 		mem_ctx, &state, struct g_lock_watch_data_state);
 	if (req == NULL) {
@@ -1840,6 +1859,8 @@ void g_lock_wake_watchers(struct g_lock_ctx *ctx, TDB_DATA key)
 {
 	NTSTATUS status;
 
+	SMB_ASSERT(!ctx->busy);
+
 	status = dbwrap_do_locked(ctx->db, key, g_lock_wake_watchers_fn, NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		DBG_DEBUG("dbwrap_do_locked returned %s\n",