Changed ngx_chain_update_chains() to test tag first (ticket #2248). Without this change, aio used with HTTP/2 can result in connection hang, as observed with "aio threads; aio_write on;" and proxying (ticket #2248). The problem is that HTTP/2 updates buffers outside of the output filters (notably, marks them as sent), and then posts a write event to call output filters. If a filter does not call the next one for some reason (for example, because of an AIO operation in progress), this might result in a state when the owner of a buffer already called ngx_chain_update_chains() and can reuse the buffer, while the same buffer is still sitting in the busy chain of some other filter. In the particular case a buffer was sitting in output chain's ctx->busy, and was reused by event pipe. Output chain's ctx->busy was permanently blocked by it, and this resulted in connection hang. Fix is to change ngx_chain_update_chains() to skip buffers from other modules unconditionally, without trying to wait for these buffers to become empty.

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


have=NGX_WIN32 . auto/have_headers

CORE_INCS="$WIN32_INCS"
CORE_DEPS="$WIN32_DEPS"
CORE_SRCS="$WIN32_SRCS $IOCP_SRCS"
OS_CONFIG="$WIN32_CONFIG"
NGX_ICONS="$NGX_WIN32_ICONS"
SELECT_SRCS=$WIN32_SELECT_SRCS
POLL_SRCS=$WIN32_POLL_SRCS

ngx_pic_opt=
ngx_binext=".exe"

case "$NGX_CC_NAME" in

    gcc)
        CORE_LIBS="$CORE_LIBS -ladvapi32 -lws2_32"
        MAIN_LINK="$MAIN_LINK -Wl,--export-all-symbols"
        MAIN_LINK="$MAIN_LINK -Wl,--out-implib=$NGX_OBJS/libnginx.a"
        MODULE_LINK="-shared -L $NGX_OBJS -lnginx"
    ;;

    *)
        CORE_LIBS="$CORE_LIBS advapi32.lib ws2_32.lib"
    ;;

esac

EVENT_MODULES="$EVENT_MODULES $IOCP_MODULE"
#EVENT_FOUND=YES

have=NGX_HAVE_INET6 . auto/have

have=NGX_HAVE_IOCP . auto/have