linux-kernel - Re: [PATCH] media: pci: intel: Balance device refcount when destroying devices

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Message-ID: <aHYJqbAgW2UX4TyB@smile.fi.intel.com>
Date: Tue, 15 Jul 2025 10:56:25 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Ma Ke <make24@...as.ac.cn>
Cc: mchehab@...nel.org, ribalda@...omium.org, rafael.j.wysocki@...el.com,
	dongcheng.yan@...el.com, gregkh@...uxfoundation.org,
	peterz@...radead.org, wentong.wu@...el.com,
	sakari.ailus@...ux.intel.com, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] media: pci: intel: Balance device refcount when
 destroying devices

On Mon, Jul 14, 2025 at 09:25:26PM +0800, Ma Ke wrote:
> Using ipu_bridge_get_ivsc_csi_dev() to locate the device could cause
> an imbalance in the device's reference count.
> ipu_bridge_get_ivsc_csi_dev() calls device_find_child_by_name() to
> implement the localization, and device_find_child_by_name() calls an
> implicit get_device() to increment the device's reference count before
> returning the pointer. Throughout the entire implementation process,
> no mechanism releases resources properly. This leads to a memory leak
> because the reference count of the device is never decremented.
> 
> As the comment of device_find_child_by_name() says, 'NOTE: you will
> need to drop the reference with put_device() after use'.
> 
> Found by code review.

Okay, but have you check unregistering process? Does it have the put_device()
for this or not?

(The analysis is partial.)

-- 
With Best Regards,
Andy Shevchenko