netdev - Re: [PATCH net-next] tcp: Revert "tcp: tcp_probe: use spin_lock

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Message-Id: <20170221.132647.1720616047649729612.davem@davemloft.net>
Date:   Tue, 21 Feb 2017 13:26:47 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     edumazet@...gle.com
Cc:     netdev@...r.kernel.org, rnsanchez@...il.com
Subject: Re: [PATCH net-next] tcp: Revert "tcp: tcp_probe: use
 spin_lock_bh()"

From: Eric Dumazet <edumazet@...gle.com>
Date: Tue, 21 Feb 2017 06:21:47 -0800

> This reverts commit e70ac171658679ecf6bea4bbd9e9325cd6079d2b.
> 
> jtcp_rcv_established() is in fact called with hard irq being disabled.
> 
> Initial bug report from Ricardo Nabinger Sanchez [1] still needs
> to be investigated, but does not look like a TCP bug.
> 
> [1] https://www.spinics.net/lists/netdev/msg420960.html
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: kernel test robot <xiaolong.ye@...el.com>
> Cc: Ricardo Nabinger Sanchez <rnsanchez@...il.com>

Applied.

But your analysis was quite sound, we can now invoke TCP input path
from user context, therefore this jprobe needs to use BH locking.  What
is the problem.