FAILED: patch "[PATCH] net: macb: initialize PTP state before registering clock" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x e1406330d70e56dd44fa6fbafc86e77e5c80c122
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026091647-cranberry-striking-e506@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e1406330d70e56dd44fa6fbafc86e77e5c80c122 Mon Sep 17 00:00:00 2001
From: Runyu Xiao <runyu.xiao@seu.edu.cn>
Date: Tue, 8 Sep 2026 18:39:24 +0800
Subject: [PATCH] net: macb: initialize PTP state before registering clock
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

gem_ptp_init() registers the PTP clock before initializing
bp->tsu_clk_lock and the TSU hardware. Since ptp_clock_register()
publishes the PTP character device, userspace may invoke PTP callbacks
before the lock and hardware are ready.

In addition, gem_ptp_init() is called from both the interface open and
resume paths. Reinitializing tsu_clk_lock there can reset the lock while
timestamp processing is using it.

This race is theoretical and has not been observed in practice.

Initialize tsu_clk_lock once during probe and initialize the TSU before
registering the PTP clock.

Fixes: ab91f0a9b5f4 ("net: macb: Add hardware PTP support")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/netdev/20260904030439.3994047-1-runyu.xiao@seu.edu.cn/
Reviewed-by: Théo Lebrun <theo.lebrun@bootlin.com>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Signed-off-by: Runyu Xiao <runyu.xiao@seu.edu.cn>
Link: https://patch.msgid.link/20260908103924.607033-1-runyu.xiao@seu.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 77dec2d6e3fb..4cb5d7088d43 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -5883,6 +5883,7 @@ static int macb_probe(struct platform_device *pdev)
 	}
 	spin_lock_init(&bp->lock);
 	spin_lock_init(&bp->stats_lock);
+	spin_lock_init(&bp->tsu_clk_lock);
 
 	/* setup capabilities */
 	macb_configure_caps(bp, macb_config);
diff --git a/drivers/net/ethernet/cadence/macb_ptp.c b/drivers/net/ethernet/cadence/macb_ptp.c
index e5195d7dac1d..6d9166389988 100644
--- a/drivers/net/ethernet/cadence/macb_ptp.c
+++ b/drivers/net/ethernet/cadence/macb_ptp.c
@@ -334,6 +334,7 @@ void gem_ptp_init(struct net_device *netdev)
 	bp->tsu_rate = bp->ptp_info->get_tsu_rate(bp);
 	bp->ptp_clock_info.max_adj = bp->ptp_info->get_ptp_max_adj();
 	gem_ptp_init_timer(bp);
+	gem_ptp_init_tsu(bp);
 	bp->ptp_clock = ptp_clock_register(&bp->ptp_clock_info, &netdev->dev);
 	if (IS_ERR(bp->ptp_clock)) {
 		pr_err("ptp clock register failed: %ld\n",
@@ -345,10 +346,6 @@ void gem_ptp_init(struct net_device *netdev)
 		return;
 	}
 
-	spin_lock_init(&bp->tsu_clk_lock);
-
-	gem_ptp_init_tsu(bp);
-
 	dev_info(&bp->pdev->dev, "%s ptp clock registered.\n",
 		 GEM_PTP_TIMER_NAME);
 }