Re: [REGRESSION] commit 66c1ca0: {fbmem: fix fb_info->lock andmm->mmap_sem ...} causes Xfbdev not working

[Krzysztof Helt]

On Sat, 11 Apr 2009 00:05:22 +0200
Andrea Righi <righi.andrea@xxxxxxxxx> wrote:

> 
> mmmh... I may have missed something, but the common fb_mmap() should
> acquire mm->mmap_sem and then info->lock, while fb_ioctl() can do that
> in reverse order (info->lock first and then mm->mmap_sem) causing the
> circular locking dependency. Are you sure that pushing info->lock down
> each driver's fb_mmap will fix the problem?

Right. The fb_mmap is called with the mmap_sem already held.
I will try other possibilities like breaking info->lock() into two
mutexex.

Something should be done to solve this problem.

Best regards,
Krzysztof

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