On Sun, Jun 03, 2001 at 05:47:19PM +0200, Anders Magnusson wrote:

 > > Does the VAX's scheme deal with that okay?
 > >
 > Not from the slave CPUs (because the chars are sent via IPI).
 > 
 > > Also, where do you want
 > > to put the new #define?  Probably should be in sys/types.h, or something,
 > > as __NO_KPRINTF_LOCK.
 > > 
 > It doesn't matter at all, I just want this to work for some degree of "work".
 > I am interested in all suggestions as long as this problem is solved.

Ok, Bill Sommerfeld mentioned something to me which sparked an idea...

In your machine/lock.h, define a KPRINTF_SLOCK_ACQUIRE like so:

#define	KPRINTF_SLOCK_ACQUIRE(alp) \
do { \
	struct cpu_info *__ci = curcpu(); \
	\
	while (__cpu_simple_lock_try(&(alp)->lock_data) == 0) { \
		if (__ci->ci_ipis_pending) \
			/* go process them */ ; \
	} \
} while (/*CONSTCOND*/0)

Then in subr_prf.c:

#ifndef	KPRINTF_SLOCK_ACQUIRE
#define	KPRINTF_SLOCK_ACQUIRE(alp)	__cpu_simple_lock(&(alp)->lock_data)
#endif

#define	KPRINTF_MUTEX_ENTER(s) \
do { \
	(s) = splhigh(); \
	KPRINTF_SLOCK_ACQUIRE(&kprintf_slock); \
} while (/*CONSTCOND*/0)

-- 
        -- Jason R. Thorpe <thorpej@zembu.com>