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Date:   Mon, 11 Mar 2019 15:06:16 +0000
From:   Vakul Garg <vakul.garg@....com>
To:     Boris Pismenny <borisp@...lanox.com>,
        Aviad Yehezkel <aviadye@...lanox.com>,
        "davejwatson@...com" <davejwatson@...com>,
        "john.fastabend@...il.com" <john.fastabend@...il.com>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     Eran Ben Elisha <eranbe@...lanox.com>
Subject: RE: [PATCH net 2/4] tls: Fix write space handling



> -----Original Message-----
> From: Boris Pismenny <borisp@...lanox.com>
> Sent: Tuesday, February 26, 2019 7:43 PM
> To: Vakul Garg <vakul.garg@....com>; Aviad Yehezkel
> <aviadye@...lanox.com>; davejwatson@...com;
> john.fastabend@...il.com; daniel@...earbox.net; netdev@...r.kernel.org
> Cc: Eran Ben Elisha <eranbe@...lanox.com>
> Subject: Re: [PATCH net 2/4] tls: Fix write space handling
> 
> 
> 
> On 2/26/2019 2:49 PM, Vakul Garg wrote:
> >
> >
> >> -----Original Message-----
> >> From: Boris Pismenny <borisp@...lanox.com>
> >> Sent: Tuesday, February 26, 2019 5:43 PM
> >> To: aviadye@...lanox.com; davejwatson@...com;
> >> john.fastabend@...il.com; daniel@...earbox.net; Vakul Garg
> >> <vakul.garg@....com>; netdev@...r.kernel.org
> >> Cc: eranbe@...lanox.com; borisp@...lanox.com
> >> Subject: [PATCH net 2/4] tls: Fix write space handling
> >>
> >> TLS device cannot use the sw context. This patch returns the original
> >> tls device write space handler and moves the sw/device specific
> >> portions to the relevant files.
> >>
> >> Fixes: a42055e8d2c3 ("net/tls: Add support for async encryption of
> >> records for performance")
> >> Signed-off-by: Boris Pismenny <borisp@...lanox.com>
> >> Reviewed-by: Eran Ben Elisha <eranbe@...lanox.com>
> >> ---
> >>   include/net/tls.h    |  3 +++
> >>   net/tls/tls_device.c | 16 ++++++++++++++++
> >>   net/tls/tls_main.c   | 17 +++++++++--------
> >>   net/tls/tls_sw.c     | 15 +++++++++++++++
> >>   4 files changed, 43 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/include/net/tls.h b/include/net/tls.h index
> >> a528a082da73..9d7c53737b13 100644
> >> --- a/include/net/tls.h
> >> +++ b/include/net/tls.h
> >> @@ -519,6 +519,9 @@ static inline bool tls_sw_has_ctx_tx(const struct
> >> sock
> >> *sk)
> >>   	return !!tls_sw_ctx_tx(ctx);
> >>   }
> >>
> >> +int tls_sw_write_space(struct sock *sk, struct tls_context *ctx);
> >> +int tls_device_write_space(struct sock *sk, struct tls_context
> >> +*ctx);
> >> +
> >>   static inline struct tls_offload_context_rx *
> >>   tls_offload_ctx_rx(const struct tls_context *tls_ctx)
> >>   {
> >> diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c index
> >> 3e5e8e021a87..e8988b3f3236 100644
> >> --- a/net/tls/tls_device.c
> >> +++ b/net/tls/tls_device.c
> >> @@ -546,6 +546,22 @@ static int tls_device_push_pending_record(struct
> >> sock *sk, int flags)
> >>   	return tls_push_data(sk, &msg_iter, 0, flags,
> >> TLS_RECORD_TYPE_DATA);
> >>   }
> >>
> >> +int tls_device_write_space(struct sock *sk, struct tls_context *ctx)
> >> +{
> >> +	int rc = 0;
> >> +
> >> +	if (!sk->sk_write_pending && tls_is_partially_sent_record(ctx)) {
> >> +		gfp_t sk_allocation = sk->sk_allocation;
> >> +
> >> +		sk->sk_allocation = GFP_ATOMIC;
> >> +		rc = tls_push_partial_record(sk, ctx,
> >> +					     MSG_DONTWAIT |
> >> MSG_NOSIGNAL);
> >> +		sk->sk_allocation = sk_allocation;
> >> +	}
> >> +
> >> +	return rc;
> >> +}
> >> +
> >>   void handle_device_resync(struct sock *sk, u32 seq, u64 rcd_sn)
> >>   {
> >>   	struct tls_context *tls_ctx = tls_get_ctx(sk); diff --git
> >> a/net/tls/tls_main.c b/net/tls/tls_main.c index
> >> 7e05af75536d..11c1980a75cb 100644
> >> --- a/net/tls/tls_main.c
> >> +++ b/net/tls/tls_main.c
> >> @@ -212,7 +212,7 @@ int tls_push_partial_record(struct sock *sk,
> >> struct tls_context *ctx,
> >>   static void tls_write_space(struct sock *sk)
> >>   {
> >>   	struct tls_context *ctx = tls_get_ctx(sk);
> >> -	struct tls_sw_context_tx *tx_ctx = tls_sw_ctx_tx(ctx);
> >> +	int rc;
> >>
> >>   	/* If in_tcp_sendpages call lower protocol write space handler
> >>   	 * to ensure we wake up any waiting operations there. For example
> >> @@ -223,14 +223,15 @@ static void tls_write_space(struct sock *sk)
> >>   		return;
> >>   	}
> >>
> >> -	/* Schedule the transmission if tx list is ready */
> >> -	if (is_tx_ready(tx_ctx) && !sk->sk_write_pending) {
> >> -		/* Schedule the transmission */
> >> -		if (!test_and_set_bit(BIT_TX_SCHEDULED, &tx_ctx-
> >>> tx_bitmask))
> >> -			schedule_delayed_work(&tx_ctx->tx_work.work, 0);
> >> -	}
> >> +#ifdef CONFIG_TLS_DEVICE
> >> +	if (ctx->tx_conf == TLS_HW)
> >> +		rc = tls_device_write_space(sk, ctx);
> >> +	else
> >> +#endif
> >> +		rc = tls_sw_write_space(sk, ctx);
> >>
> >> -	ctx->sk_write_space(sk);
> >> +	if (!rc)
> >
> > Why do we need to check 'rc'?
> >
> > If it is required, then ' ctx->sk_write_space(sk)' can move to
> > tls_device_write_space() since  tls_sw_write_space() always returns '0'.
> >
> 
> It is not necessary in the software code path due to the delayed work that is
> there. But, we need in the device flow. I'll move it there.
> 
 
Removal of ctx->sk_write_space(sk) has broken software code flow.
The ktls send stops and user space application waits infinitely.
When tls_write_space() gets invoked tcp has been able to transmit some data.
Shouldn't we unconditionally call ctx->sk_write_space() in order to inform 
user space application about availability of buffer space?

Please advise. I would submit the patch.

> 
> >> +		ctx->sk_write_space(sk);
> >>   }
> >>
> >>   static void tls_ctx_free(struct tls_context *ctx)
> >> diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
> >> index 1cc830582fa8..4afa67b00aaf 100644
> >> --- a/net/tls/tls_sw.c
> >> +++ b/net/tls/tls_sw.c
> >> @@ -2126,6 +2126,21 @@ static void tx_work_handler(struct
> work_struct
> >> *work)
> >>   	release_sock(sk);
> >>   }
> >>
> >> +int tls_sw_write_space(struct sock *sk, struct tls_context *ctx)
> >> +{
> >> +	struct tls_sw_context_tx *tx_ctx = tls_sw_ctx_tx(ctx);
> >> +
> >> +	/* Schedule the transmission if tx list is ready */
> >> +	if (is_tx_ready(tx_ctx) && !sk->sk_write_pending) {
> >> +		/* Schedule the transmission */
> >> +		if (!test_and_set_bit(BIT_TX_SCHEDULED,
> >> +				      &tx_ctx->tx_bitmask))
> >> +			schedule_delayed_work(&tx_ctx->tx_work.work, 0);
> >> +	}
> >> +
> >> +	return 0;
> >> +}
> >> +
> >>   int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
> >>   {
> >>   	struct tls_context *tls_ctx = tls_get_ctx(sk);
> >> --
> >> 2.12.2
> >

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