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.

VER=	$(shell grep 'define NGINX_VERSION' src/core/nginx.h		\
		| sed -e 's/^.*"\(.*\)".*/\1/')
NGINX=	nginx-$(VER)
TEMP=	tmp
XSLS?=	xslscript.pl


all:		changes

changes:	$(TEMP)/$(NGINX)/CHANGES.ru				\
		$(TEMP)/$(NGINX)/CHANGES


$(TEMP)/$(NGINX)/CHANGES.ru:	docs/dtd/changes.dtd			\
				docs/xml/nginx/changes.xml		\
				docs/xml/change_log_conf.xml		\
				docs/xslt/changes.xslt

	mkdir -p $(TEMP)/$(NGINX)

	xmllint --noout --valid docs/xml/nginx/changes.xml
	xsltproc --stringparam lang ru					\
		-o $@ docs/xslt/changes.xslt docs/xml/nginx/changes.xml


$(TEMP)/$(NGINX)/CHANGES:	docs/dtd/changes.dtd			\
				docs/xml/nginx/changes.xml		\
				docs/xml/change_log_conf.xml		\
				docs/xslt/changes.xslt

	mkdir -p $(TEMP)/$(NGINX)

	xmllint --noout --valid docs/xml/nginx/changes.xml
	xsltproc --stringparam lang en					\
		-o $@ docs/xslt/changes.xslt docs/xml/nginx/changes.xml


docs/xslt/changes.xslt:		docs/xsls/changes.xsls

	$(XSLS) -o $@ $<