How can I wake up one process from the wait queue?

[Raghavendra]

On Thursday 30 October 2014 02:02 PM, Rock Lee wrote:
>
> Hi, everyone
>
> I am implementing a simple driver to experiment with wait queue.Two or 
> more read processes block until a write process changes a flag and 
> call wake_up_interruptible().I expect that a write process will only 
> wake up one read process.However, once a write process calls 
> wake_up_interruptible() , all the read processes are awaken. How can I 
> wake up one process from the wait queue?
>
You can use exclusive wait queues, which wakes up only one process from 
the queue.

Although the general idea that is followed is: all the process are woken 
up once the resource is made available. And then the access to that 
resource is guarded by a lock, which in turn allows only one process to 
access the resource. Rest of the processes are pushed backed to sleep(or 
busy wait).

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