Re: [PATCH][RFC] Spinlock-timeout

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

> Here's a revision to the patch that uses a HAVE_ARCH_GET_TB to allow
> archs use their timebases if they have one, and if they don't, it uses
> jiffies.  time_after_eq() is used to do the jiffy checking.
> 
> I also left all of the arch/*/Kconfig changes in until a debug Kconfig
> is done.  I pretty much added in the spinlock timeout on all archs that
> have CONFIG_DEBUG_SPINLOCK.  If I missed your arch, I'm sorry.    

Nah, that's not how the abstraction should be done. Much simpler in
fact. Just do something like this in the generic code:

#ifndef ARCH_HAS_SPINLOCK_TIMEOUT
#define get_spinlock_timeout() (jiffies + (SPINLOCK_TIMEOUT * HZ))
#define check_spinlock_timeout(timeout) (time_after_eq(jiffies, timeout))
#endif

That's all. Then, any arch who has it's own implementation of these 2
function will #define ARCH_HAS_SPINLOCK_TIMEOUT and implement them the
way it wants. We shouldn't let anything like get_tb() slip into a common
file, it's totally PPC specific. Other archs may have different counters
they can use to impement the same thing. That part should be entirely
self contained in asm-xxx

Ben.