John Fastabend f0a8c1257f tls: possible hang when do_tcp_sendpages hits sndbuf is full case ... [ Upstream commit 67db7cd249 ] Currently, the lower protocols sk_write_space handler is not called if TLS is sending a scatterlist via tls_push_sg. However, normally tls_push_sg calls do_tcp_sendpage, which may be under memory pressure, that in turn may trigger a wait via sk_wait_event. Typically, this happens when the in-flight bytes exceed the sdnbuf size. In the normal case when enough ACKs are received sk_write_space() will be called and the sk_wait_event will be woken up allowing it to send more data and/or return to the user. But, in the TLS case because the sk_write_space() handler does not wake up the events the above send will wait until the sndtimeo is exceeded. By default this is MAX_SCHEDULE_TIMEOUT so it look like a hang to the user (especially this impatient user). To fix this pass the sk_write_space event to the lower layers sk_write_space event which in the TCP case will wake any pending events. I observed the above while integrating sockmap and ktls. It initially appeared as test_sockmap (modified to use ktls) occasionally hanging. To reliably reproduce this reduce the sndbuf size and stress the tls layer by sending many 1B sends. This results in every byte needing a header and each byte individually being sent to the crypto layer. Signed-off-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Dave Watson <davejwatson@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2018-10-03 17:00:58 -07:00
..
Kconfig	tls: update Kconfig	2017-06-17 22:56:46 -04:00
Makefile	tls: kernel TLS support	2017-06-15 12:12:40 -04:00
tls_main.c	tls: possible hang when do_tcp_sendpages hits sndbuf is full case	2018-10-03 17:00:58 -07:00
tls_sw.c	tls: zero the crypto information from tls_context before freeing	2018-09-29 03:06:01 -07:00