Mercurial > hg > nginx
view src/http/v2/ngx_http_v2_encode.c @ 7951:c7a8bdf5af55
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.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Sat, 30 Oct 2021 02:39:19 +0300 |
parents | 87e9e4aabf1b |
children | 336084ff943b |
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/* * Copyright (C) Nginx, Inc. * Copyright (C) Valentin V. Bartenev */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> static u_char *ngx_http_v2_write_int(u_char *pos, ngx_uint_t prefix, ngx_uint_t value); u_char * ngx_http_v2_string_encode(u_char *dst, u_char *src, size_t len, u_char *tmp, ngx_uint_t lower) { size_t hlen; hlen = ngx_http_v2_huff_encode(src, len, tmp, lower); if (hlen > 0) { *dst = NGX_HTTP_V2_ENCODE_HUFF; dst = ngx_http_v2_write_int(dst, ngx_http_v2_prefix(7), hlen); return ngx_cpymem(dst, tmp, hlen); } *dst = NGX_HTTP_V2_ENCODE_RAW; dst = ngx_http_v2_write_int(dst, ngx_http_v2_prefix(7), len); if (lower) { ngx_strlow(dst, src, len); return dst + len; } return ngx_cpymem(dst, src, len); } static u_char * ngx_http_v2_write_int(u_char *pos, ngx_uint_t prefix, ngx_uint_t value) { if (value < prefix) { *pos++ |= value; return pos; } *pos++ |= prefix; value -= prefix; while (value >= 128) { *pos++ = value % 128 + 128; value /= 128; } *pos++ = (u_char) value; return pos; }