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SubjectRe: [OT] Major Clock Drift
Date
From
> > 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);



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