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SubjectRe: [PATCH] Change the spin_lock/unlock_irq interface in proc_alloc_inum() function
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在 2016/3/2 11:09, Al Viro 写道:
> On Wed, Mar 02, 2016 at 10:47:59AM +0800, MaJun wrote:
>> From: Ma Jun <majun258@huawei.com>
>>
>> The spin_lock/unlock_irq interface is not safe when this function is called
>> at some case which need irq disabled.
>
>> For example:
>> spin_lock_irqsave()
>> |
>> request_irq() --> proc_alloc_inum()
>> |
>> spin_unlock_irqrestore()
>
> Do you even read your own patch?
>
>> if (!ida_pre_get(&proc_inum_ida, GFP_KERNEL))
> ^^^^^^^^^^
> This.
>
> It can block. You *can't* call that under spin_lock_irqsave(). At all.
> You also can't do request_irq() under a spinlock, no matter whether you
> disable irqs or not - it also blocks. So does proc_mkdir(), for that
> matter, and not only in proc_alloc_inum().
>
> NAKed. Don't do it. request_irq() is not to be called under spinlocks,
> with or without irqs disabled.
>

Sorry,I made a wrong example for this problem.
I want to say this interface may change the irq status after this function
be called.

Thanks!
MaJun

> .
>

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