Why timer interrupt is disabled?

[David Woodhouse]

andreev at niisi.msk.ru said:
>  It may happen that one  CPU is reading and other CPU is writing data
> at the same time. So, the  flash memory can return status value
> instead of data, for example. Does  the chip->mutex lock provides
> necessary synchronization?

Yes. The flash driver is required to make that work correctly. The (blkdev)
request functions aren't required to be reentrant anyway, I believe.

> I look at the other block device drivers code and found, that
> io_request  handlers do sti() in some cases. If you still don`t want
> to do it, we  could use a softirq. In the do_fd_request(), the "bottom
> halves" is used  for example. We could use a "bottom halves" or even a
> tasklet in our  case. What do you think about this?

Take a look at the way it's done by the mtdblock device, with a kernel 
thread.

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dwmw2