From: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org
[ Upstream commit d905d06e64b0eb3da43af6186c132f5282197998 ]
Device can be unbound, so driver must also release memory for the wakeup source.
Signed-off-by: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org Link: https://lore.kernel.org/r/20250406-mfd-device-wakekup-leak-v1-3-318e14bdba0a... Signed-off-by: Lee Jones lee@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org ---
Now let me understand the difference between the fixes - the historical commits show two patterns: 1. Using `devm_device_init_wakeup()` - automatically handles cleanup 2. Manual cleanup by calling `device_init_wakeup(dev, false)` in remove functions
Let me check if this specific commit has `Cc: stable@vger.kernel.org` in the message:
Based on my analysis of this commit and comparison with the similar historical commits, here is my assessment:
**YES**
This commit should be backported to stable kernel trees for the following reasons:
## Analysis
### **Code Change Analysis** The commit adds a single line in the `max14577_i2c_remove()` function: ```c + device_init_wakeup(max14577->dev, false); ```
This addition occurs at drivers/mfd/max14577.c:459, right before `mfd_remove_devices()` is called.
### **Bug Fix Characteristics** 1. **Memory Leak Fix**: The commit fixes a wakeup source memory leak that occurs when the device is unbound. When `device_init_wakeup(dev, true)` is called during probe (line 442), it allocates memory for wakeup source structures. Without the corresponding cleanup call, this memory is leaked on device removal.
2. **Small and Contained**: The fix is minimal - a single line addition that mirrors the cleanup pattern used throughout the kernel.
3. **Low Risk**: The change has extremely low regression risk since it only adds proper cleanup that should have been there originally.
### **Comparison with Historical Similar Commits** Looking at the provided historical commits, there are two categories:
**YES commits (backported)**: - `gpio: mpc8xxx: Fix wakeup source leaks on device unbind` - Same exact pattern and includes `Cc: stable@vger.kernel.org` - `gpio: zynq: Fix wakeup source leaks on device unbind` - Same exact pattern and includes `Cc: stable@vger.kernel.org`
**NO commits (not backported)**: - IIO driver commits that use `devm_device_init_wakeup()` instead of manual cleanup
The key difference is that the YES commits use the same fix pattern as this MFD commit - manual cleanup in the remove function, while the NO commits use the `devm_` managed approach that automatically handles cleanup.
### **Impact Assessment** - **User Impact**: Memory leaks on device unbind affect systems where MFD devices are frequently bound/unbound - **Subsystem**: MFD (Multi-Function Device) is a core kernel subsystem used by many embedded systems - **Regression Risk**: Minimal - adding proper cleanup cannot cause functional regression
### **Stable Tree Criteria Met** 1. ✅ Fixes an important bug (memory leak) 2. ✅ Small and contained change 3. ✅ No architectural changes 4. ✅ Minimal risk of regression 5. ✅ Follows established patterns seen in other backported commits
The commit follows the exact same pattern as the GPIO driver commits that were successfully backported to stable trees (commits #1 and #2 in the historical examples), making it a clear candidate for backporting.
drivers/mfd/max14577.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/mfd/max14577.c b/drivers/mfd/max14577.c index be185e9d5f16b..c9e56145b08bd 100644 --- a/drivers/mfd/max14577.c +++ b/drivers/mfd/max14577.c @@ -467,6 +467,7 @@ static int max14577_i2c_remove(struct i2c_client *i2c) { struct max14577 *max14577 = i2c_get_clientdata(i2c);
+ device_init_wakeup(max14577->dev, false); mfd_remove_devices(max14577->dev); regmap_del_irq_chip(max14577->irq, max14577->irq_data); if (max14577->dev_type == MAXIM_DEVICE_TYPE_MAX77836)