linux-kernel - Re: [PATCH net-next v9 3/7] net: stmmac: refactor FPE verification process

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Message-ID: <20240906125258.d7rhhcjdic3quqg2@skbuf>
Date: Fri, 6 Sep 2024 15:52:58 +0300
From: Vladimir Oltean <olteanv@...il.com>
To: Furong Xu <0x1207@...il.com>
Cc: Serge Semin <fancer.lancer@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Jose Abreu <joabreu@...opsys.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Joao Pinto <jpinto@...opsys.com>, netdev@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	rmk+kernel@...linux.org.uk, linux@...linux.org.uk, xfr@...look.com,
	Vladimir Oltean <vladimir.oltean@....com>
Subject: Re: [PATCH net-next v9 3/7] net: stmmac: refactor FPE verification
 process

On Fri, Sep 06, 2024 at 12:55:58PM +0800, Furong Xu wrote:
> @@ -5979,44 +5956,29 @@ static int stmmac_set_features(struct net_device *netdev,
>  static void stmmac_fpe_event_status(struct stmmac_priv *priv, int status)
>  {
>  	struct stmmac_fpe_cfg *fpe_cfg = &priv->fpe_cfg;
> -	enum stmmac_fpe_state *lo_state = &fpe_cfg->lo_fpe_state;
> -	enum stmmac_fpe_state *lp_state = &fpe_cfg->lp_fpe_state;
> -	bool *hs_enable = &fpe_cfg->hs_enable;
>  
> -	if (status == FPE_EVENT_UNKNOWN || !*hs_enable)
> -		return;
> +	/* This is interrupt context, just spin_lock() */
> +	spin_lock(&fpe_cfg->lock);
>  
> -	/* If LP has sent verify mPacket, LP is FPE capable */
> -	if ((status & FPE_EVENT_RVER) == FPE_EVENT_RVER) {
> -		if (*lp_state < FPE_STATE_CAPABLE)
> -			*lp_state = FPE_STATE_CAPABLE;
> +	if (!fpe_cfg->pmac_enabled || status == FPE_EVENT_UNKNOWN)
> +		goto unlock_out;
>  
> -		/* If user has requested FPE enable, quickly response */
> -		if (*hs_enable)
> -			stmmac_fpe_send_mpacket(priv, priv->ioaddr,
> -						fpe_cfg,
> -						MPACKET_RESPONSE);
> -	}
> +	/* LP has sent verify mPacket */
> +	if ((status & FPE_EVENT_RVER) == FPE_EVENT_RVER)
> +		stmmac_fpe_send_mpacket(priv, priv->ioaddr, fpe_cfg,
> +					MPACKET_RESPONSE);
>  
> -	/* If Local has sent verify mPacket, Local is FPE capable */
> -	if ((status & FPE_EVENT_TVER) == FPE_EVENT_TVER) {
> -		if (*lo_state < FPE_STATE_CAPABLE)
> -			*lo_state = FPE_STATE_CAPABLE;
> -	}
> +	/* Local has sent verify mPacket */
> +	if ((status & FPE_EVENT_TVER) == FPE_EVENT_TVER &&
> +	    fpe_cfg->status != ETHTOOL_MM_VERIFY_STATUS_SUCCEEDED)
> +		fpe_cfg->status = ETHTOOL_MM_VERIFY_STATUS_VERIFYING;
>  
> -	/* If LP has sent response mPacket, LP is entering FPE ON */
> +	/* LP has sent response mPacket */
>  	if ((status & FPE_EVENT_RRSP) == FPE_EVENT_RRSP)
> -		*lp_state = FPE_STATE_ENTERING_ON;
> +		fpe_cfg->status = ETHTOOL_MM_VERIFY_STATUS_SUCCEEDED;

Nitpick, doesn't affect normal behavior.
If the link partner crafts an unsolicited Response mPacket, and we have
verify_enabled = false, what we should do is we should ignore it.
But what the code does is to transition the state to SUCCEEDED, as if
verify_enabled was true.

We should ignore FPE_EVENT_RRSP events if we are in the
ETHTOOL_MM_VERIFY_STATUS_DISABLED state.

Depending on how the maintainers feel, this could also be handled in a
subsequent patch.

>  
> -	/* If Local has sent response mPacket, Local is entering FPE ON */
> -	if ((status & FPE_EVENT_TRSP) == FPE_EVENT_TRSP)
> -		*lo_state = FPE_STATE_ENTERING_ON;
> -
> -	if (!test_bit(__FPE_REMOVING, &priv->fpe_task_state) &&
> -	    !test_and_set_bit(__FPE_TASK_SCHED, &priv->fpe_task_state) &&
> -	    priv->fpe_wq) {
> -		queue_work(priv->fpe_wq, &priv->fpe_task);
> -	}
> +unlock_out:
> +	spin_unlock(&fpe_cfg->lock);
>  }
>  
>  static void stmmac_common_interrupt(struct stmmac_priv *priv)