Re: tickle nmi watchdog whilst doing serial writes.

Andi Kleen
2005-05-15T12:20:21Z

Russell King <rmk+lkml@arm.linux.org.uk> writes:

> On Sun, May 15, 2005 at 01:38:02PM +0200, Andi Kleen wrote:
>> Dave Jones <davej@redhat.com> writes:
>> >
>> > #include <asm/io.h>
>> > #include <asm/irq.h>
>> > @@ -2099,8 +2100,10 @@ static inline void wait_for_xmitr(struct
>> > if (up->port.flags & UPF_CONS_FLOW) {
>> > tmout = 1000000;
>> > while (--tmout &&
>> > - ((serial_in(up, UART_MSR) & UART_MSR_CTS) == 0))
>> > + ((serial_in(up, UART_MSR) & UART_MSR_CTS) == 0)) {
>> > udelay(1);
>> > + touch_nmi_watchdog();
>>
>> Note that touch_nmi_watchdog is not exported on i386 - Linus vetoed
>> that some time ago. The real fix of course is to use schedule_timeout(),
>> but that might break printk() with interrupts off :/
>
> Not to mention printk() from atomic contexts and panic(). No,
> schedule_timeout() is _not_ a "real fix" but a kludge.

Then someone needs to convince Linus to export touch_nmi_watchdog
again.

Or how about checking if interrupts are off here (iirc we have
a generic function for that now) and then using
a smaller timeout and otherwise schedule_timeout() ?

-Andi