Re: [patch 9/9]Four new i2c drivers and __init/__exit cleanup to i2c

Jeff Garzik
2002-09-15T23:27:26Z

Russell King wrote:
> On Sun, Sep 15, 2002 at 07:18:46PM -0400, Jeff Garzik wrote:
>
>>Albert Cranford wrote:
>>
>>>--- linux/drivers/i2c/i2c-elektor.c.orig 2002-09-14 22:10:45.000000000 -0400
>>>+++ linux-2.5.34/drivers/i2c/i2c-elektor.c 2002-09-15 01:18:55.000000000 -0400
>>>@@ -125,12 +125,12 @@
>>> int timeout = 2;
>>>
>>> if (irq > 0) {
>>>- cli();
>>>+ local_irq_disable();
>>> if (pcf_pending == 0) {
>>> interruptible_sleep_on_timeout(&pcf_wait, timeout*HZ );
>>> } else
>>> pcf_pending = 0;
>>>- sti();
>>>+ local_irq_enable();
>>> } else {
>>> udelay(100);
>>> }
>>
>>
>>
>>this is _not_ the way to fix... use a proper spinlock
>
>
> You can't hold a spinlock and sleep though, was one of my points back
> in August. (Albert submitted a patch with all cli()/sti() converted
> to spin_lock_irqsave()/spin_unlock_irqrestore().)
>

whoops, you're right.

That follows along with my suggestion in another email, then :) use a
semaphore. The timeout can be handled with a kernel timer. The timeout
is clearly multiple seconds, so there's no fine grain involved.

AND, since the timeout is multiple seconds, the code should not be
disable interrupts for that long anyway.

Jeff