s3:blocking: use timeval_expired(&state->endtime) to stop processing

This is less racy than timeval_elapsed() > 0
as the current time is already expired and timeout = 0
will always work correct.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14113

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>

diff --git a/source3/smbd/blocking.c b/source3/smbd/blocking.c
index a87d62d910aaa60e6fec9acabe5be32f86be241f..9f64a86d3eea09641b8027be17e91bdf69e3cc2d 100644 (file)
--- a/source3/smbd/blocking.c
+++ b/source3/smbd/blocking.c
@@ -159,9 +159,10 @@ struct tevent_req *smbd_smb1_do_locks_send(
        struct share_mode_lock *lck = NULL;
        struct server_id blocking_pid = { 0 };
        uint64_t blocking_smblctx = 0;
-       struct timeval endtime;
+       struct timeval endtime = { 0 };
        NTSTATUS status = NT_STATUS_OK;
        bool ok;
+       bool expired;
 
        req = tevent_req_create(
                mem_ctx, &state, struct smbd_smb1_do_locks_state);
@@ -251,19 +252,28 @@ struct tevent_req *smbd_smb1_do_locks_send(
                        state->timeout = lp_lock_spin_time();
                }
        }
+       state->endtime = timeval_current_ofs_msec(state->timeout);
 
        DBG_DEBUG("timeout=%"PRIu32", blocking_smblctx=%"PRIu64"\n",
                  state->timeout,
                  blocking_smblctx);
 
        /*
+        * The client specified timeout expired
+        * avoid further retries.
+        *
+        * Otherwise keep waiting either waiting
+        * for changes in locking.tdb or the polling
+        * mode timers waiting for posix locks.
+        *
         * If the endtime is not elapsed yet,
         * it means we'll retry after a timeout.
         * In that case we'll have to return
         * NT_STATUS_FILE_LOCK_CONFLICT
         * instead of NT_STATUS_LOCK_NOT_GRANTED.
         */
-       if (state->timeout == 0) {
+       expired = timeval_expired(&state->endtime);
+       if (expired) {
                status = state->deny_status;
                tevent_req_nterror(req, status);
                goto done;
@@ -278,7 +288,6 @@ struct tevent_req *smbd_smb1_do_locks_send(
        TALLOC_FREE(lck);
        tevent_req_set_callback(subreq, smbd_smb1_do_locks_retry, req);
 
-       state->endtime = timeval_current_ofs_msec(state->timeout);
        endtime = state->endtime;
 
        if (blocking_smblctx == UINT64_MAX) {
@@ -363,13 +372,13 @@ static void smbd_smb1_do_locks_try(struct tevent_req *req)
        struct smbd_smb1_do_locks_state *retry_state = tevent_req_data(
                retry_req, struct smbd_smb1_do_locks_state);
        struct share_mode_lock *lck;
-       struct timeval endtime;
+       struct timeval endtime = { 0 };
        struct server_id blocking_pid = { 0 };
        uint64_t blocking_smblctx = 0;
        struct tevent_req *subreq = NULL;
        NTSTATUS status;
        bool ok;
-       double elapsed;
+       bool expired;
 
        lck = get_existing_share_mode_lock(state, fsp->file_id);
        if (tevent_req_nomem(lck, req)) {
@@ -393,7 +402,7 @@ static void smbd_smb1_do_locks_try(struct tevent_req *req)
        }
 
        /*
-        * The client specified timeout elapsed
+        * The client specified timeout expired
         * avoid further retries.
         *
         * Otherwise keep waiting either waiting
@@ -406,8 +415,8 @@ static void smbd_smb1_do_locks_try(struct tevent_req *req)
         * NT_STATUS_FILE_LOCK_CONFLICT
         * instead of NT_STATUS_LOCK_NOT_GRANTED.
         */
-       elapsed = timeval_elapsed(&state->endtime);
-       if (elapsed > 0) {
+       expired = timeval_expired(&state->endtime);
+       if (expired) {
                status = state->deny_status;
                goto done;
        }