+static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
+ int nonblock)
+{
+ ssize_t ret;
+ struct signalfd_lockctx lk;
+ DECLARE_WAITQUEUE(wait, current);
+
+ if (!signalfd_lock(ctx, &lk))
+ return 0;
+
+ ret = dequeue_signal(lk.tsk, &ctx->sigmask, info);
+ switch (ret) {
+ case 0:
+ if (!nonblock)
+ break;
+ ret = -EAGAIN;
+ default:
+ signalfd_unlock(&lk);
+ return ret;
+ }
+
+ add_wait_queue(&ctx->wqh, &wait);
+ for (;;) {
+ set_current_state(TASK_INTERRUPTIBLE);
+ ret = dequeue_signal(lk.tsk, &ctx->sigmask, info);
+ signalfd_unlock(&lk);
+ if (ret != 0)
+ break;
+ if (signal_pending(current)) {
+ ret = -ERESTARTSYS;
+ break;
+ }
+ schedule();
+ ret = signalfd_lock(ctx, &lk);
+ if (unlikely(!ret)) {
+ /*
+ * Let the caller read zero byte, ala socket
+ * recv() when the peer disconnect. This test
+ * must be done before doing a dequeue_signal(),
+ * because if the sighand has been orphaned,
+ * the dequeue_signal() call is going to crash
+ * because ->sighand will be long gone.
+ */
+ break;
+ }
+ }
+
+ remove_wait_queue(&ctx->wqh, &wait);
+ __set_current_state(TASK_RUNNING);
+
+ return ret;
+}
+