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SubjectRe: [PATCH v3 2/6] PM / Runtime: introduce pm_runtime_set[get]_memalloc_noio()
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On Wednesday 31 October 2012 00:00:56 Ming Lei wrote:
> On Tue, Oct 30, 2012 at 11:38 PM, Alan Stern <stern@rowland.harvard.edu> wrote:
>
> >
> > Okay, I see your point. But acquiring the lock here doesn't solve the
> > problem. Suppose a thread is about to reset a USB mass-storage device.
> > It acquires the lock and sees that the noio flag is clear. But before
> > it can issue the reset, another thread sets the noio flag.
>
> If the USB mass-storage device is being reseted, the flag should be set
> already generally. If the flag is still unset, that means the disk/network
> device isn't added into system(or removed just now), so memory allocation
> with block I/O should be allowed during the reset. Looks it isn't one problem,
> isn't it?

I am afraid it is, because a disk may just have been probed as the deviceis being reset.

Regards
Oliver



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