Messages in this thread | | | Date | Mon, 15 Nov 2010 11:36:54 -0800 | From | Jeremy Fitzhardinge <> | Subject | Re: [PATCH 01/20] x86/ticketlock: clean up types and accessors |
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On 11/13/2010 01:57 AM, Américo Wang wrote: > On Wed, Nov 03, 2010 at 10:59:42AM -0400, Jeremy Fitzhardinge wrote: > ... >> static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) >> { >> - int inc = 0x00010000; >> - int tmp; >> + unsigned inc = 1 << TICKET_SHIFT; >> + unsigned tmp; > Please don't use old implicit-int.
I don't mind much either way, but I don't think I've seen anyone worry about this before.
>> - return (((tmp >> TICKET_SHIFT) - tmp) & ((1 << TICKET_SHIFT) - 1)) > 1; >> + return ((tmp.tail - tmp.head) & TICKET_MASK) > 1; > > There is a type promotion here.
...
>> } >> >> #ifndef CONFIG_PARAVIRT_SPINLOCKS >> diff --git a/arch/x86/include/asm/spinlock_types.h b/arch/x86/include/asm/spinlock_types.h >> index dcb48b2..4582640 100644 >> --- a/arch/x86/include/asm/spinlock_types.h >> +++ b/arch/x86/include/asm/spinlock_types.h >> @@ -5,11 +5,27 @@ >> # error "please don't include this file directly" >> #endif >> >> +#include <linux/types.h> >> + >> +#if (CONFIG_NR_CPUS < 256) >> +typedef u8 __ticket_t; >> +#else >> +typedef u16 __ticket_t; >> +#endif >> + >> +#define TICKET_SHIFT (sizeof(__ticket_t) * 8) >> +#define TICKET_MASK ((1 << TICKET_SHIFT) - 1) > > So here you may need to cast the result to __ticket_t.
OK.
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