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Date: Sat, 6 Jan 2024 15:04:01 +0800
From: Jisheng Zhang <jszhang@kernel.org>
To: Petr Tesarik <petr@tesarici.cz>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Jose Abreu <joabreu@synopsys.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Andrew Lunn <andrew@lunn.ch>,
	"open list:STMMAC ETHERNET DRIVER" <netdev@vger.kernel.org>,
	"moderated list:ARM/STM32 ARCHITECTURE" <linux-stm32@st-md-mailman.stormreply.com>,
	"moderated list:ARM/STM32 ARCHITECTURE" <linux-arm-kernel@lists.infradead.org>,
	open list <linux-kernel@vger.kernel.org>, stable@vger.kernel.org
Subject: Re: [PATCH net] net: stmmac: fix ethtool per-queue  statistics
Message-ID: <ZZj7YfYa3Hl5TW1n@xhacker>
References: <20240105201642.30904-1-petr@tesarici.cz>
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In-Reply-To: <20240105201642.30904-1-petr@tesarici.cz>

On Fri, Jan 05, 2024 at 09:16:42PM +0100, Petr Tesarik wrote:
> Fix per-queue statistics for devices with more than one queue.
> 
> The output data pointer is currently reset in each loop iteration,
> effectively summing all queue statistics in the first four u64 values.
> 
> The summary values are not even labeled correctly. For example, if eth0 has
> 2 queues, ethtool -S eth0 shows:
> 
>      q0_tx_pkt_n: 374 (actually tx_pkt_n over all queues)
>      q0_tx_irq_n: 23  (actually tx_normal_irq_n over all queues)
>      q1_tx_pkt_n: 462 (actually rx_pkt_n over all queues)
>      q1_tx_irq_n: 446 (actually rx_normal_irq_n over all queues)
>      q0_rx_pkt_n: 0
>      q0_rx_irq_n: 0
>      q1_rx_pkt_n: 0
>      q1_rx_irq_n: 0
> 
> Fixes: 133466c3bbe1 ("net: stmmac: use per-queue 64 bit statistics where necessary")
> Cc: stable@vger.kernel.org
> Signed-off-by: Petr Tesarik <petr@tesarici.cz>

Good catch! I mixed this with the statics sum up for
stmmac_qstats_string[].

Reviewed-by: Jisheng Zhang <jszhang@kernel.org>

> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
> index f628411ae4ae..112a36a698f1 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
> @@ -543,15 +543,12 @@ static void stmmac_get_per_qstats(struct stmmac_priv *priv, u64 *data)
>  	u32 rx_cnt = priv->plat->rx_queues_to_use;
>  	unsigned int start;
>  	int q, stat;
> -	u64 *pos;
>  	char *p;
>  
> -	pos = data;
>  	for (q = 0; q < tx_cnt; q++) {
>  		struct stmmac_txq_stats *txq_stats = &priv->xstats.txq_stats[q];
>  		struct stmmac_txq_stats snapshot;
>  
> -		data = pos;
>  		do {
>  			start = u64_stats_fetch_begin(&txq_stats->syncp);
>  			snapshot = *txq_stats;
> @@ -559,17 +556,15 @@ static void stmmac_get_per_qstats(struct stmmac_priv *priv, u64 *data)
>  
>  		p = (char *)&snapshot + offsetof(struct stmmac_txq_stats, tx_pkt_n);
>  		for (stat = 0; stat < STMMAC_TXQ_STATS; stat++) {
> -			*data++ += (*(u64 *)p);
> +			*data++ = (*(u64 *)p);
>  			p += sizeof(u64);
>  		}
>  	}
>  
> -	pos = data;
>  	for (q = 0; q < rx_cnt; q++) {
>  		struct stmmac_rxq_stats *rxq_stats = &priv->xstats.rxq_stats[q];
>  		struct stmmac_rxq_stats snapshot;
>  
> -		data = pos;
>  		do {
>  			start = u64_stats_fetch_begin(&rxq_stats->syncp);
>  			snapshot = *rxq_stats;
> @@ -577,7 +572,7 @@ static void stmmac_get_per_qstats(struct stmmac_priv *priv, u64 *data)
>  
>  		p = (char *)&snapshot + offsetof(struct stmmac_rxq_stats, rx_pkt_n);
>  		for (stat = 0; stat < STMMAC_RXQ_STATS; stat++) {
> -			*data++ += (*(u64 *)p);
> +			*data++ = (*(u64 *)p);
>  			p += sizeof(u64);
>  		}
>  	}
> -- 
> 2.43.0
>