linux-kernel - [PATCH v3] pci: controller: pci-ftpci100: Release the clock resources

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Message-Id: <20230508043641.23807-1-yejunyan@hust.edu.cn>
Date:   Mon,  8 May 2023 12:36:41 +0800
From:   Junyan Ye <yejunyan@...t.edu.cn>
To:     Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Wei Yongjun <weiyongjun1@...wei.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Andrew Murray <amurray@...goodpenguin.co.uk>
Cc:     hust-os-kernel-patches@...glegroups.com,
        Junyan Ye <yejunyan@...t.edu.cn>,
        Dongliang Mu <dzm91@...t.edu.cn>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3] pci: controller: pci-ftpci100: Release the clock resources

Smatch reported:
1. drivers/pci/controller/pci-ftpci100.c:526 faraday_pci_probe() warn:
'clk' from clk_prepare_enable() not released on lines: 442,451,462,478,512,517.
2. drivers/pci/controller/pci-ftpci100.c:526 faraday_pci_probe() warn:
'p->bus_clk' from clk_prepare_enable() not released on lines: 451,462,478,512,517.

The clock resource is obtained by devm_clk_get(), and then
clk_prepare_enable() makes the clock resource ready for use. After that,
clk_disable_unprepare() should be called to release the clock resource
when it is no longer needed. However, while doing some error handling
in faraday_pci_probe(), clk_disable_unprepare() is not called to release
clk and p->bus_clk before returning. These return lines are exactly 442,
451, 462, 478, 512, 517.

Fix this warning by replacing devm_clk_get() with devm_clk_get_enabled(),
which is equivalent to devm_clk_get() + clk_prepare_enable(). And with
devm_clk_get_enabled(), the clock will automatically be disabled,
unprepared and freed when the device is unbound from the bus.

Fixes: b3c433efb8a3 ("PCI: faraday: Fix wrong pointer passed to PTR_ERR()")
Fixes: 2eeb02b28579 ("PCI: faraday: Add clock handling")
Fixes: 783a862563f7 ("PCI: faraday: Use pci_parse_request_of_pci_ranges()")
Fixes: d3c68e0a7e34 ("PCI: faraday: Add Faraday Technology FTPCI100 PCI Host Bridge driver")
Fixes: f1e8bd21e39e ("PCI: faraday: Convert IRQ masking to raw PCI config accessors")
Reviewed-by: Dongliang Mu <dzm91@...t.edu.cn>
Signed-off-by: Junyan Ye <yejunyan@...t.edu.cn>
---
v2 -> v3: Rebase to v6.4-rc1 and modify commit message.
v1 -> v2: Switch from clk_disable_unprepare() to devm_clk_get_enabled() to release the clock.
This issue is found by static analyzer.

 drivers/pci/controller/pci-ftpci100.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/drivers/pci/controller/pci-ftpci100.c b/drivers/pci/controller/pci-ftpci100.c
index ecd3009df586..6e7981d2ed5e 100644
--- a/drivers/pci/controller/pci-ftpci100.c
+++ b/drivers/pci/controller/pci-ftpci100.c
@@ -429,22 +429,12 @@ static int faraday_pci_probe(struct platform_device *pdev)
 	p->dev = dev;
 
 	/* Retrieve and enable optional clocks */
-	clk = devm_clk_get(dev, "PCLK");
+	clk = devm_clk_get_enabled(dev, "PCLK");
 	if (IS_ERR(clk))
 		return PTR_ERR(clk);
-	ret = clk_prepare_enable(clk);
-	if (ret) {
-		dev_err(dev, "could not prepare PCLK\n");
-		return ret;
-	}
-	p->bus_clk = devm_clk_get(dev, "PCICLK");
+	p->bus_clk = devm_clk_get_enabled(dev, "PCICLK");
 	if (IS_ERR(p->bus_clk))
 		return PTR_ERR(p->bus_clk);
-	ret = clk_prepare_enable(p->bus_clk);
-	if (ret) {
-		dev_err(dev, "could not prepare PCICLK\n");
-		return ret;
-	}
 
 	p->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(p->base))
-- 
2.25.1