tree f1924cedc2aa178d4a1bc953204fce035a6a4233
parent 765c9c639fbb132af0cafc6e1da22fe6cea26bb8
author Eric Dumazet <edumazet@google.com> 1432067215 -0700
committer David S. Miller <davem@davemloft.net> 1432241800 -0400

tcp: add a force_schedule argument to sk_stream_alloc_skb()

In commit 8e4d980ac215 ("tcp: fix behavior for epoll edge trigger")
we fixed a possible hang of TCP sockets under memory pressure,
by allowing sk_stream_alloc_skb() to use sk_forced_mem_schedule()
if no packet is in socket write queue.

It turns out there are other cases where we want to force memory
schedule :

tcp_fragment() & tso_fragment() need to split a big TSO packet into
two smaller ones. If we block here because of TCP memory pressure,
we can effectively block TCP socket from sending new data.
If no further ACK is coming, this hang would be definitive, and socket
has no chance to effectively reduce its memory usage.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>