[Xen-devel] Re: [PATCH 04/20] x86/ticketlock: make large and small ticket versions of spin_lock the same

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 11/12/2010 04:19 AM, Srivatsa Vaddagiri wrote:
> On Wed, Nov 03, 2010 at 10:59:45AM -0400, Jeremy Fitzhardinge wrote:
>> Make the bulk of __ticket_spin_lock look identical for large and small
>> number of cpus.
> [snip]
>
>>  #if (NR_CPUS < 256)
>>  static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock)
>>  {
>> -    register union {
>> -            struct __raw_tickets tickets;
>> -            unsigned short slock;
>> -    } inc = { .slock = 1 << TICKET_SHIFT };
>> +    register struct __raw_tickets inc = { .tail = 1 };
> [snip]
>
>>  #else
>>  static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock)
>>  {
>> -    unsigned inc = 1 << TICKET_SHIFT;
>> -    __ticket_t tmp;
>> +    register struct __raw_tickets inc = { .tickets.tail = 1 };
> s/.tickets//?
>
> Otherwise I get a compile error for NR_CPUS > 256, with just 4 patches 
> applied.

Yeah, likely.  That's precisely why I wanted to make them the same ;).

    J

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