Re: [OT] Major Clock Drift

[Alan Cox]

> > Why are interrupts being disabled for vesafb scrolling anyway ?
> 
> Console writes happen under spin_lock_irq(console_lock).
> 
> The only reason for this which I can see: the kernel
> can call printk() from interrupt context.

We certainly need to be able to call printk from interrupt context so that
bit is in itself reasonable, but not the cost.

Suppose vesafb did something like this, dropping the printk lock

        if(test_and_set_bit(0, &vesafb_lock))
        {
                if(in_interrupt())
                {
                        // remember which bit of the dmesg ring to queue
                        queued_writes=1;
                        return;
                }
        }
        /* for the re-entry case this will block */
        down(&vesafb_mutex);
again:
        do the usual stuff 
        if(queued_writes)
        {
                dequeue_write_buffer();
                goto again;
        }
        up(&vesafb_mutex);
        clear_bit(0, &vesafb_lock);


        
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
Please read the FAQ at http://www.tux.org/lkml/