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

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Le 08/05/2023 à 06:36, Junyan Ye a écrit :
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@xxxxxxxxxxx>
Signed-off-by: Junyan Ye <yejunyan@xxxxxxxxxxx>
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 */


completely unrelated to your patch, but this comments state "optional". The code below seems to make both clocks mandatory.

Moreover, a few lines later, we have:
    if (!IS_ERR(p->bus_clk)) {
which seems to say that bus_clk is optional.

This was introduced by 2eeb02b28579.

Just a guess, but either the comment should be updated, or the code modified.

Just my 2c,


-	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))

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