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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