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From: Jakub Kicinski <jakub.kicinski@netronome.com>
To: John Fastabend <john.fastabend@gmail.com>
Cc: daniel@iogearbox.io, ast@kernel.org, netdev@vger.kernel.org,
	edumazet@google.com, bpf@vger.kernel.org
Subject: Re: [PATCH 1/2] tls: remove close callback sock unlock/lock and flush_sync
Date: Fri, 28 Jun 2019 11:31:00 -0700	[thread overview]
Message-ID: <20190628113100.597bfbe6@cakuba.netronome.com> (raw)
In-Reply-To: <5d1620374694e_26962b1f6a4fa5c4f2@john-XPS-13-9370.notmuch>

On Fri, 28 Jun 2019 07:12:07 -0700, John Fastabend wrote:
> Yeah seems possible although never seen in my testing. So I'll
> move the test_bit() inside the lock and do a ctx check to ensure
> still have the reference.
> 
>   CPU 0 (free)           CPU 1 (wq)
> 
>   lock(sk)
>                          lock(sk)
>   set_bit()
>   cancel_work()
>   release
>                          ctx = tls_get_ctx(sk)
>                          unlikely(!ctx) <- we may have free'd 
>                          test_bit()
>                          ...
>                          release()
> 
> or
> 
>   CPU 0 (free)           CPU 1 (wq)
> 
>                          lock(sk)
>   lock(sk)
>                          ctx = tls_get_ctx(sk)
>                          unlikely(!ctx)
>                          test_bit()
>                          ...
>                          release()
>   set_bit()
>   cancel_work()
>   release

Hmm... perhaps it's cleanest to stop the work from scheduling before we
proceed?

close():
	while (!test_and_set(SHED))
		flush();

	lock(sk);
	...

We just need to move init work, no?

FWIW I never tested his async crypto stuff, I wonder if there is a way
to convince normal CPU crypto to pretend to be async?

  reply	other threads:[~2019-06-28 18:31 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-27 17:36 [PATCH 0/2] tls, add unhash callback John Fastabend
2019-06-27 17:36 ` [PATCH 1/2] tls: remove close callback sock unlock/lock and flush_sync John Fastabend
2019-06-27 23:44   ` Jakub Kicinski
2019-06-28 14:12     ` John Fastabend
2019-06-28 18:31       ` Jakub Kicinski [this message]
2019-06-28 19:40         ` John Fastabend
2019-06-28 22:48           ` Jakub Kicinski
2019-06-29  0:20             ` John Fastabend
2019-06-29  0:59               ` Jakub Kicinski
2019-06-29  3:46                 ` Jakub Kicinski
2019-06-27 17:36 ` [PATCH 2/2] bpf: tls, implement unhash to avoid transition out of ESTABLISHED John Fastabend
2019-06-27 18:16 ` [PATCH 0/2] tls, add unhash callback John Fastabend

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