From 58cc13ab291cac5b13462006e3feb780178ef5f3 Mon Sep 17 00:00:00 2001 From: Max Romanov Date: Fri, 10 Apr 2020 16:21:58 +0300 Subject: Resolving a racing condition while adding ports on the app's side. An earlier attempt (ad6265786871) to resolve this condition on the router's side added a new issue: the app could get a request before acquiring a port. --- src/nxt_unit.c | 28 +++++++++++++++++++++++++--- 1 file changed, 25 insertions(+), 3 deletions(-) (limited to 'src/nxt_unit.c') diff --git a/src/nxt_unit.c b/src/nxt_unit.c index c2e7f198..67244420 100644 --- a/src/nxt_unit.c +++ b/src/nxt_unit.c @@ -4282,16 +4282,38 @@ nxt_unit_add_port(nxt_unit_ctx_t *ctx, nxt_unit_port_t *port) int rc; nxt_unit_impl_t *lib; nxt_unit_process_t *process; - nxt_unit_port_impl_t *new_port; + nxt_unit_port_impl_t *new_port, *old_port; lib = nxt_container_of(ctx->unit, nxt_unit_impl_t, unit); + pthread_mutex_lock(&lib->mutex); + + old_port = nxt_unit_port_hash_find(&lib->ports, &port->id, 0); + + if (nxt_slow_path(old_port != NULL)) { + nxt_unit_debug(ctx, "add_port: duplicate %d,%d in_fd %d out_fd %d", + port->id.pid, port->id.id, + port->in_fd, port->out_fd); + + if (port->in_fd != -1) { + close(port->in_fd); + port->in_fd = -1; + } + + if (port->out_fd != -1) { + close(port->out_fd); + port->out_fd = -1; + } + + pthread_mutex_unlock(&lib->mutex); + + return NXT_UNIT_OK; + } + nxt_unit_debug(ctx, "add_port: %d,%d in_fd %d out_fd %d", port->id.pid, port->id.id, port->in_fd, port->out_fd); - pthread_mutex_lock(&lib->mutex); - process = nxt_unit_process_get(ctx, port->id.pid); if (nxt_slow_path(process == NULL)) { rc = NXT_UNIT_ERROR; -- cgit