Dealing with buffered data with upstream generated response

[Umesh Sirsiwal]

I am developing a body filter which transforms outgoing stream. As part 
of the function, the incoming stream is copied in new buffer and sent. 
This in some cases results in a condition where my filter has busy 
buffers but the upper layers don't have any busy buffer. In our case the 
data is generated by upstream module. Since upstream module does not pay 
attention to connection->buffered, the output_filter is never called 
again to flush my busy buffers and the transfer just hangs.

Adding r->connection->buffered to the or condition solves the hang.

            if (u->out_bufs || u->busy_bufs) {
                 rc = ngx_http_output_filter(r, u->out_bufs);

                 if (rc == NGX_ERROR) {
                     ngx_http_upstream_finalize_request(r, u, 0);
                     return;
                 }

                 ngx_chain_update_chains(&u->free_bufs, &u->busy_bufs,
&u->out_bufs, u->output.tag);
             }

Is this nginx bug or am I missing something?

-Umesh