linux-kernel - [PATCH net 12/13] net: stmmac: Stop overriding the PTP clock info static instance

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Message-ID: <20230313224237.28757-13-Sergey.Semin@baikalelectronics.ru>
Date:   Tue, 14 Mar 2023 01:42:36 +0300
From:   Serge Semin <Sergey.Semin@...kalelectronics.ru>
To:     Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Ong Boon Leong <boon.leong.ong@...el.com>,
        Voon Weifeng <weifeng.voon@...el.com>,
        Wong Vee Khee <vee.khee.wong@...ux.intel.com>,
        Tan Tee Min <tee.min.tan@...el.com>,
        Richard Cochran <richardcochran@...il.com>
CC:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Serge Semin <fancer.lancer@...il.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        Christian Marangi <ansuelsmth@...il.com>,
        Biao Huang <biao.huang@...iatek.com>,
        Yang Yingliang <yangyingliang@...wei.com>,
        <netdev@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        Jose Abreu <Jose.Abreu@...opsys.com>
Subject: [PATCH net 12/13] net: stmmac: Stop overriding the PTP clock info static instance

It had been defined as constant before commit 9a8a02c9d46d ("net: stmmac:
Add Flexible PPS support"). But then it was converted to be just static,
which fields may get to be modified on each stmmac_ptp_register()
invocation. Since that method is called from the driver probe method, a
concurrent DW *MAC NIC initialization causes the race condition for the
updated stmmac_ptp_clock_ops fields. That also may lead to setting an
inappropriate max_adj value, which was specific for one device, was
written to the stmmac_ptp_clock_ops, but then copied to the private
ptp_clock_info instance unmodified.

So to speak let's leave the stmmac_ptp_clock_ops content untouched and
just copy it to the device-specific instance of the ptp_clock_info
structure, which fields could be then accordingly modified. After that we
can get the const qualifier back to the stmmac_ptp_clock_ops instance
definition.

While at it remove pointless zero-initialization of the
stmmac_ptp_clock_ops fields. It's redundant since the structure is static.

Fixes: 9a8a02c9d46d ("net: stmmac: Add Flexible PPS support")
Fixes: 190f73ab4c43 ("net: stmmac: setup higher frequency clk support for EHL & TGL")
Fixes: f4da56529da6 ("net: stmmac: Add support for external trigger timestamping")
Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
---
 .../net/ethernet/stmicro/stmmac/stmmac_ptp.c  | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
index b4388ca8d211..19a28b1cc272 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
@@ -254,15 +254,10 @@ static int stmmac_getcrosststamp(struct ptp_clock_info *ptp,
 }
 
 /* structure describing a PTP hardware clock */
-static struct ptp_clock_info stmmac_ptp_clock_ops = {
+static const struct ptp_clock_info stmmac_ptp_clock_ops = {
 	.owner = THIS_MODULE,
 	.name = "stmmac ptp",
 	.max_adj = 62500000,
-	.n_alarm = 0,
-	.n_ext_ts = 0, /* will be overwritten in stmmac_ptp_register */
-	.n_per_out = 0, /* will be overwritten in stmmac_ptp_register */
-	.n_pins = 0,
-	.pps = 0,
 	.adjfine = stmmac_adjust_freq,
 	.adjtime = stmmac_adjust_time,
 	.gettime64 = stmmac_get_time,
@@ -287,21 +282,21 @@ void stmmac_ptp_register(struct stmmac_priv *priv)
 		priv->pps[i].available = true;
 	}
 
-	if (priv->plat->ptp_max_adj)
-		stmmac_ptp_clock_ops.max_adj = priv->plat->ptp_max_adj;
-
 	/* Calculate the clock domain crossing (CDC) error if necessary */
 	priv->plat->cdc_error_adj = 0;
 	if (priv->plat->has_gmac4 && priv->plat->clk_ptp_rate)
 		priv->plat->cdc_error_adj = (2 * NSEC_PER_SEC) / priv->plat->clk_ptp_rate;
 
-	stmmac_ptp_clock_ops.n_per_out = priv->dma_cap.pps_out_num;
-	stmmac_ptp_clock_ops.n_ext_ts = priv->dma_cap.aux_snapshot_n;
-
 	rwlock_init(&priv->ptp_lock);
 	mutex_init(&priv->aux_ts_lock);
 	priv->ptp_clock_ops = stmmac_ptp_clock_ops;
 
+	if (priv->plat->ptp_max_adj)
+		priv->ptp_clock_ops.max_adj = priv->plat->ptp_max_adj;
+
+	priv->ptp_clock_ops.n_per_out = priv->dma_cap.pps_out_num;
+	priv->ptp_clock_ops.n_ext_ts = priv->dma_cap.aux_snapshot_n;
+
 	priv->ptp_clock = ptp_clock_register(&priv->ptp_clock_ops,
 					     priv->device);
 	if (IS_ERR(priv->ptp_clock)) {
-- 
2.39.2