FAILED: patch "[PATCH] PCI: rcar-host: Drop PMSR spinlock" 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 0a8f173d9dad13930d5888505dc4c4fd6a1d4262
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025101648-abruptly-poncho-afdd@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

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

From 0a8f173d9dad13930d5888505dc4c4fd6a1d4262 Mon Sep 17 00:00:00 2001
From: Marek Vasut <marek.vasut+renesas@mailbox.org>
Date: Tue, 9 Sep 2025 18:26:24 +0200
Subject: [PATCH] PCI: rcar-host: Drop PMSR spinlock

The pmsr_lock spinlock used to be necessary to synchronize access to the
PMSR register, because that access could have been triggered from either
config space access in rcar_pcie_config_access() or an exception handler
rcar_pcie_aarch32_abort_handler().

The rcar_pcie_aarch32_abort_handler() case is no longer applicable since
commit 6e36203bc14c ("PCI: rcar: Use PCI_SET_ERROR_RESPONSE after read
which triggered an exception"), which performs more accurate, controlled
invocation of the exception, and a fixup.

This leaves rcar_pcie_config_access() as the only call site from which
rcar_pcie_wakeup() is called. The rcar_pcie_config_access() can only be
called from the controller struct pci_ops .read and .write callbacks,
and those are serialized in drivers/pci/access.c using raw spinlock
'pci_lock' . It should be noted that CONFIG_PCI_LOCKLESS_CONFIG is never
set on this platform.

Since the 'pci_lock' is a raw spinlock , and the 'pmsr_lock' is not a
raw spinlock, this constellation triggers 'BUG: Invalid wait context'
with CONFIG_PROVE_RAW_LOCK_NESTING=y .

Remove the pmsr_lock to fix the locking.

Fixes: a115b1bd3af0 ("PCI: rcar: Add L1 link state fix into data abort hook")
Reported-by: Duy Nguyen <duy.nguyen.rh@renesas.com>
Reported-by: Thuan Nguyen <thuan.nguyen-hong@banvien.com.vn>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20250909162707.13927-1-marek.vasut+renesas@mailbox.org

diff --git a/drivers/pci/controller/pcie-rcar-host.c b/drivers/pci/controller/pcie-rcar-host.c
index 4780e0109e58..625a00f3b223 100644
--- a/drivers/pci/controller/pcie-rcar-host.c
+++ b/drivers/pci/controller/pcie-rcar-host.c
@@ -52,20 +52,13 @@ struct rcar_pcie_host {
 	int			(*phy_init_fn)(struct rcar_pcie_host *host);
 };
 
-static DEFINE_SPINLOCK(pmsr_lock);
-
 static int rcar_pcie_wakeup(struct device *pcie_dev, void __iomem *pcie_base)
 {
-	unsigned long flags;
 	u32 pmsr, val;
 	int ret = 0;
 
-	spin_lock_irqsave(&pmsr_lock, flags);
-
-	if (!pcie_base || pm_runtime_suspended(pcie_dev)) {
-		ret = -EINVAL;
-		goto unlock_exit;
-	}
+	if (!pcie_base || pm_runtime_suspended(pcie_dev))
+		return -EINVAL;
 
 	pmsr = readl(pcie_base + PMSR);
 
@@ -87,8 +80,6 @@ static int rcar_pcie_wakeup(struct device *pcie_dev, void __iomem *pcie_base)
 		writel(L1FAEG | PMEL1RX, pcie_base + PMSR);
 	}
 
-unlock_exit:
-	spin_unlock_irqrestore(&pmsr_lock, flags);
 	return ret;
 }