Intention of this bit is to force pushing of the existing
send queue when TCP_CORK or TCP_NODELAY state changes via
setsockopt().
But it's easy to create a situation where the bit never
clears. For example, if the send queue starts empty:
1) set TCP_NODELAY
2) clear TCP_NODELAY
3) set TCP_CORK
4) do small write()
The current code will leave TCP_NAGLE_PUSH set after that
sequence. Unconditionally clearing the bit when new data
is added via skb_entail() solves the problem.
Signed-off-by: David S. Miller <davem@davemloft.net>
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