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From: Jakub Kicinski <kuba@kernel.org>
To: Jochen Henneberg <jh@henneberg-systemdesign.com>
Cc: netdev@vger.kernel.org,
	Giuseppe Cavallaro <peppe.cavallaro@st.com>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Jose Abreu <joabreu@synopsys.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Paolo Abeni <pabeni@redhat.com>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Ong Boon Leong <boon.leong.ong@intel.com>,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH net V2 1/2] net: stmmac: Premature loop termination check was ignored on rx
Date: Fri, 17 Mar 2023 22:21:17 -0700	[thread overview]
Message-ID: <20230317222117.3520d4cf@kernel.org> (raw)
In-Reply-To: <20230316075940.695583-2-jh@henneberg-systemdesign.com>

On Thu, 16 Mar 2023 08:59:39 +0100 Jochen Henneberg wrote:
> The premature loop termination check makes sense only in case of the
> jump to read_again where the count may have been updated. But
> read_again did not include the check.
> 
> Fixes: ec222003bd94 ("net: stmmac: Prepare to add Split Header support")
> Signed-off-by: Jochen Henneberg <jh@henneberg-systemdesign.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index e4902a7bb61e..ea51c7c93101 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -5221,10 +5221,10 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
>  			len = 0;
>  		}
>  
> +read_again:
>  		if (count >= limit)
>  			break;

Are you sure? Can you provide more detailed analysis?
Do you observe a problem / error in real life or is this theoretical?

As far as I can tell only path which jumps to read_again after doing
count++ is via the drain_data jump, but I can't tell how it's
discarding subsequent segments in that case..

> -read_again:
>  		buf1_len = 0;
>  		buf2_len = 0;
>  		entry = next_entry;


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WARNING: multiple messages have this Message-ID (diff)
From: Jakub Kicinski <kuba@kernel.org>
To: Jochen Henneberg <jh@henneberg-systemdesign.com>
Cc: netdev@vger.kernel.org,
	Giuseppe Cavallaro <peppe.cavallaro@st.com>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Jose Abreu <joabreu@synopsys.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Paolo Abeni <pabeni@redhat.com>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Ong Boon Leong <boon.leong.ong@intel.com>,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH net V2 1/2] net: stmmac: Premature loop termination check was ignored on rx
Date: Fri, 17 Mar 2023 22:21:17 -0700	[thread overview]
Message-ID: <20230317222117.3520d4cf@kernel.org> (raw)
In-Reply-To: <20230316075940.695583-2-jh@henneberg-systemdesign.com>

On Thu, 16 Mar 2023 08:59:39 +0100 Jochen Henneberg wrote:
> The premature loop termination check makes sense only in case of the
> jump to read_again where the count may have been updated. But
> read_again did not include the check.
> 
> Fixes: ec222003bd94 ("net: stmmac: Prepare to add Split Header support")
> Signed-off-by: Jochen Henneberg <jh@henneberg-systemdesign.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index e4902a7bb61e..ea51c7c93101 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -5221,10 +5221,10 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
>  			len = 0;
>  		}
>  
> +read_again:
>  		if (count >= limit)
>  			break;

Are you sure? Can you provide more detailed analysis?
Do you observe a problem / error in real life or is this theoretical?

As far as I can tell only path which jumps to read_again after doing
count++ is via the drain_data jump, but I can't tell how it's
discarding subsequent segments in that case..

> -read_again:
>  		buf1_len = 0;
>  		buf2_len = 0;
>  		entry = next_entry;


  parent reply	other threads:[~2023-03-18  5:22 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-14 12:37 [PATCH net 0/2] net: stmmac: Premature loop termination check was ignored Jochen Henneberg
2023-03-14 12:37 ` Jochen Henneberg
2023-03-14 12:37 ` [PATCH net 1/2] " Jochen Henneberg
2023-03-14 12:37   ` Jochen Henneberg
2023-03-14 14:44   ` Piotr Raczynski
2023-03-14 14:44     ` Piotr Raczynski
2023-03-14 15:01     ` Jochen Henneberg
2023-03-14 15:01       ` Jochen Henneberg
2023-03-15  8:59       ` Piotr Raczynski
2023-03-15  8:59         ` Piotr Raczynski
2023-03-15  9:13         ` Jochen Henneberg
2023-03-15  9:13           ` Jochen Henneberg
2023-03-14 12:37 ` [PATCH net 2/2] " Jochen Henneberg
2023-03-14 12:37   ` Jochen Henneberg
2023-03-16  7:59 ` [PATCH net V2 0/2] " Jochen Henneberg
2023-03-16  7:59   ` Jochen Henneberg
2023-03-16  7:59   ` [PATCH net V2 1/2] net: stmmac: Premature loop termination check was ignored on rx Jochen Henneberg
2023-03-16  7:59     ` Jochen Henneberg
2023-03-17 12:32     ` Piotr Raczynski
2023-03-17 12:32       ` Piotr Raczynski
2023-03-18  5:21     ` Jakub Kicinski [this message]
2023-03-18  5:21       ` Jakub Kicinski
2023-03-18  8:38       ` Jochen Henneberg
2023-03-18  8:38         ` Jochen Henneberg
2023-03-19  2:01         ` Jakub Kicinski
2023-03-19  2:01           ` Jakub Kicinski
2023-03-20  9:04           ` Jochen Henneberg
2023-03-20  9:04             ` Jochen Henneberg
2023-03-20 18:36             ` Jakub Kicinski
2023-03-20 18:36               ` Jakub Kicinski
2023-03-21 18:53               ` Jochen Henneberg
2023-03-21 18:53                 ` Jochen Henneberg
2023-03-16  7:59   ` [PATCH net V2 2/2] net: stmmac: Premature loop termination check was ignored on ZC rx Jochen Henneberg
2023-03-16  7:59     ` Jochen Henneberg
2023-03-17 12:32     ` Piotr Raczynski
2023-03-17 12:32       ` Piotr Raczynski
2023-03-16 23:20   ` [PATCH net V2 0/2] net: stmmac: Premature loop termination check was ignored Horatiu Vultur
2023-03-16 23:20     ` Horatiu Vultur
2023-03-17 12:31   ` Piotr Raczynski
2023-03-17 12:31     ` Piotr Raczynski

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