[PATCH AUTOSEL 6.15 12/21] mfd: sprd-sc27xx: Fix wakeup source leaks on device unbind

[Sasha Levin <sashal@kernel.org>]

From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

[ Upstream commit 37ef4aa4039c42f4b15dc7e40d3e437b7f031522 ]

Device can be unbound, so driver must also release memory for the wakeup
source.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250406-mfd-device-wakekup-leak-v1-8-318e14bdba0a@linaro.org
Signed-off-by: Lee Jones <lee@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

**YES**

This commit should be backported to stable kernel trees. Here's my
detailed analysis:

## Resource Leak Analysis

The commit fixes a genuine resource leak in the sprd-sc27xx MFD driver.
When `device_init_wakeup(&spi->dev, true)` is called in the probe
function (line 213), it:

1. **Allocates kernel resources**: Creates wakeup source objects and
   sysfs entries
2. **Sets device capability flags**: Marks the device as wakeup-capable
3. **Registers with PM subsystem**: Adds the device to power management
   tracking

However, the driver **lacks a remove function** to clean up these
resources when the device is unbound.

## Code Change Analysis

The fix changes from:
```c
device_init_wakeup(&spi->dev, true);
```

To:
```c
ret = devm_device_init_wakeup(&spi->dev);
if (ret)
    return dev_err_probe(&spi->dev, ret, "Failed to init wakeup\n");
```

This uses the **managed version** (`devm_device_init_wakeup`) which
automatically calls cleanup when the device is removed, eliminating the
leak.

## Backport Justification

**1. Bug Fix Nature**: This addresses a clear resource leak affecting
production systems with removable devices or driver reloading scenarios.

**2. Minimal Risk**: The change is contained to a single function call
with identical functionality, just with automatic cleanup.

**3. Critical Subsystem**: MFD drivers control PMICs (Power Management
ICs), which are essential for power management and system stability.

**4. Pattern Consistency**: The fix follows the same pattern as the
approved similar commits for gpio drivers (mpc8xxx and zynq), which were
both marked for backporting.

**5. Clear Impact**: Resource leaks in device drivers can accumulate
over time and affect system stability, especially in embedded systems
where this PMIC driver is commonly used.

**6. Small, Contained Change**: The modification is minimal and self-
contained, reducing regression risk.

The commit clearly states the problem, provides a proper solution using
managed resources, and affects a driver commonly used in production
embedded systems where resource leaks can be particularly problematic.

 drivers/mfd/sprd-sc27xx-spi.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/mfd/sprd-sc27xx-spi.c b/drivers/mfd/sprd-sc27xx-spi.c
index 7186e2108108f..d6b4350779e6a 100644
--- a/drivers/mfd/sprd-sc27xx-spi.c
+++ b/drivers/mfd/sprd-sc27xx-spi.c
@@ -210,7 +210,10 @@ static int sprd_pmic_probe(struct spi_device *spi)
 		return ret;
 	}
 
-	device_init_wakeup(&spi->dev, true);
+	ret = devm_device_init_wakeup(&spi->dev);
+	if (ret)
+		return dev_err_probe(&spi->dev, ret, "Failed to init wakeup\n");
+
 	return 0;
 }
 
-- 
2.39.5