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.


CFLAGS =	-c -zq -bt=nt -ot -op -oi -oe -s -bm $(CPU_OPT)
PCREFLAGS =	-DHAVE_CONFIG_H -DPCRE_STATIC -DPOSIX_MALLOC_THRESHOLD=10 &
		-DSUPPORT_PCRE8 -DHAVE_MEMMOVE


pcre.lib:
	cd $(PCRE)

	wcl386 $(CFLAGS) -i=. $(PCREFLAGS) pcre_*.c

	dir /b *.obj > pcre.lst

	wlib -n pcre.lib @pcre.lst

pcre.h:
	cd $(PCRE)

	copy /y pcre.h.generic pcre.h
	copy /y config.h.generic config.h
	copy /y pcre_chartables.c.dist pcre_chartables.c