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Date: Fri, 16 Jun 2006 14:07:18 +0530 (IST)
Subject: Block driver question (MPC852 with DoC)
From: deepesh@india.tejasnetworks.com
To: linuxppc-dev@ozlabs.org
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Processor: MPC852
OS : linuxppc-2.4.20 from denx
DoC: Disk On Chip, A block device.


We are using DiskOnChip on our board. And we have got a block driver from
the vendor, which can be insmoded.

The request function of the block driver:
DeviceRequest() {
   some error checkings;
   list_add_tail(&queue,&requestsList);
   wake_up(&waitQueueHead);
}

There is an kernel thread which does the final block read-writes to the
disk on chip:

IOKernelThread() {
    while(1) {
       set_current_state(TASK_INTERRUPTIBLE);
       interruptible_sleep_on_timeout(&waitQueueHead,1);
       while(!list_empty(&requestsList)) {
          read/write to the disk;
          list_del(&queue);
       }
    }

}

The list manipulations happen in the DeviceRequest and the IOKernelThread.
Is there a potential chance of a race condition, when a timer interrupt
occurs?

Thank you,
Deepesh