On 4/23/2015 1:08 PM, Jia-Ju Bai wrote:
I am very sorry to trouble you.
I find that resource management is error-prone when writing Linux drivers, and many problems may occur, such as resource leaks. Meanwhile, I find that many applied patches in the kernel mailing list focus on releasing allocated resources, especially in error-handling paths.
Therefore, I have a question: is it possible to automatically release allocated resources in drivers before unloading and in error-handling paths?
Yes, there's managed device API, look for functions starting with devm_. There's one limitation though: it can be used only in the driver's probe() method, so can't be used when e.g. network device is being opened.
I think many APIs, such as kmalloc, can also be managed like garbage collection in Java. Maybe the performance is a matter.
I am looking forward to your reply, thanks!
Such questions should actually be asked on the mailing lists, not personally.
I am sorry for that, and I will cc to the mailing lists and other maintainers.
I find that some common APIs are not managed, such as napi_enable and napi_start_queue. Is it possible to provide managed APIs for them?
No, they're only called from ndo_open() method IIRC. The device managed APIs can only be called at the device probing time.
I also find many drivers do not use these managed APIs, especially in ethernet card drivers (like e100, r8169). Is it possible to change them?
Patches welcome. :-)
Best wishes, Jia-Ju Bai
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