From 75790028fda676ecf107087165b7bed982d50e09 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Mon, 2 Sep 2019 20:06:27 +0200 Subject: [PATCH] 4.4-stable patches added patches: tcp-make-sure-epollout-wont-be-missed.patch --- queue-4.4/series | 1 + ...cp-make-sure-epollout-wont-be-missed.patch | 82 +++++++++++++++++++ 2 files changed, 83 insertions(+) create mode 100644 queue-4.4/tcp-make-sure-epollout-wont-be-missed.patch diff --git a/queue-4.4/series b/queue-4.4/series index 594ff0b2419..cbef9fb70d5 100644 --- a/queue-4.4/series +++ b/queue-4.4/series @@ -56,3 +56,4 @@ watchdog-bcm2835_wdt-fix-module-autoload.patch tcp-fix-tcp_rtx_queue_tail-in-case-of-empty-retransm.patch alsa-usb-audio-fix-a-stack-buffer-overflow-bug-in-check_input_term.patch alsa-usb-audio-fix-an-oob-bug-in-parse_audio_mixer_unit.patch +tcp-make-sure-epollout-wont-be-missed.patch diff --git a/queue-4.4/tcp-make-sure-epollout-wont-be-missed.patch b/queue-4.4/tcp-make-sure-epollout-wont-be-missed.patch new file mode 100644 index 00000000000..0041c1fb091 --- /dev/null +++ b/queue-4.4/tcp-make-sure-epollout-wont-be-missed.patch @@ -0,0 +1,82 @@ +From foo@baz Mon 02 Sep 2019 08:05:10 PM CEST +From: Eric Dumazet +Date: Fri, 16 Aug 2019 21:26:22 -0700 +Subject: tcp: make sure EPOLLOUT wont be missed + +From: Eric Dumazet + +[ Upstream commit ef8d8ccdc216f797e66cb4a1372f5c4c285ce1e4 ] + +As Jason Baron explained in commit 790ba4566c1a ("tcp: set SOCK_NOSPACE +under memory pressure"), it is crucial we properly set SOCK_NOSPACE +when needed. + +However, Jason patch had a bug, because the 'nonblocking' status +as far as sk_stream_wait_memory() is concerned is governed +by MSG_DONTWAIT flag passed at sendmsg() time : + + long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT); + +So it is very possible that tcp sendmsg() calls sk_stream_wait_memory(), +and that sk_stream_wait_memory() returns -EAGAIN with SOCK_NOSPACE +cleared, if sk->sk_sndtimeo has been set to a small (but not zero) +value. + +This patch removes the 'noblock' variable since we must always +set SOCK_NOSPACE if -EAGAIN is returned. + +It also renames the do_nonblock label since we might reach this +code path even if we were in blocking mode. + +Fixes: 790ba4566c1a ("tcp: set SOCK_NOSPACE under memory pressure") +Signed-off-by: Eric Dumazet +Cc: Jason Baron +Reported-by: Vladimir Rutsky +Acked-by: Soheil Hassas Yeganeh +Acked-by: Neal Cardwell +Acked-by: Jason Baron +Signed-off-by: David S. Miller +Signed-off-by: Greg Kroah-Hartman +--- + net/core/stream.c | 16 +++++++++------- + 1 file changed, 9 insertions(+), 7 deletions(-) + +--- a/net/core/stream.c ++++ b/net/core/stream.c +@@ -119,7 +119,6 @@ int sk_stream_wait_memory(struct sock *s + int err = 0; + long vm_wait = 0; + long current_timeo = *timeo_p; +- bool noblock = (*timeo_p ? false : true); + DEFINE_WAIT(wait); + + if (sk_stream_memory_free(sk)) +@@ -132,11 +131,8 @@ int sk_stream_wait_memory(struct sock *s + + if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) + goto do_error; +- if (!*timeo_p) { +- if (noblock) +- set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); +- goto do_nonblock; +- } ++ if (!*timeo_p) ++ goto do_eagain; + if (signal_pending(current)) + goto do_interrupted; + sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); +@@ -168,7 +164,13 @@ out: + do_error: + err = -EPIPE; + goto out; +-do_nonblock: ++do_eagain: ++ /* Make sure that whenever EAGAIN is returned, EPOLLOUT event can ++ * be generated later. ++ * When TCP receives ACK packets that make room, tcp_check_space() ++ * only calls tcp_new_space() if SOCK_NOSPACE is set. ++ */ ++ set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); + err = -EAGAIN; + goto out; + do_interrupted: -- 2.47.3