Mercurial > hg > nginx-quic
changeset 8746:84c60a3cd12a stable-1.20
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 | 5354bf552520 |
children | 50777834e8c2 |
files | src/core/ngx_buf.c |
diffstat | 1 files changed, 4 insertions(+), 4 deletions(-) [+] |
line wrap: on
line diff
--- a/src/core/ngx_buf.c +++ b/src/core/ngx_buf.c @@ -203,16 +203,16 @@ ngx_chain_update_chains(ngx_pool_t *p, n while (*busy) { cl = *busy; - if (ngx_buf_size(cl->buf) != 0) { - break; - } - if (cl->buf->tag != tag) { *busy = cl->next; ngx_free_chain(p, cl); continue; } + if (ngx_buf_size(cl->buf) != 0) { + break; + } + cl->buf->pos = cl->buf->start; cl->buf->last = cl->buf->start;