Re: [PATCH] scheduler: adjust internal locking interface

[George Dunlap <george.dunlap@eu.citrix.com>]

On 11/10/13 15:37, Jan Beulich wrote:
>>>> On 11.10.13 at 16:29, Andrew Cooper <andrew.cooper3@citrix.com> wrote:
>> On 11/10/13 15:14, Jan Beulich wrote:
>>> +#define sched_lock(kind, param, cpu, irq, arg...) \
>>> +static inline spinlock_t *kind##_schedule_lock##irq(param EXTRA_TYPE(arg))
>> \
>>> +{ \
>>> +    for ( ; ; ) \
>>> +    { \
>>> +        spinlock_t *lock = per_cpu(schedule_data, cpu).schedule_lock; \
>>> +        /* \
>>> +         * v->processor may change when grabbing the lock; but \
>>> +         * per_cpu(v->processor) may also change, if changing cpu pool \
>>> +         * also changes the scheduler lock.  Retry until they match. \
>>> +         * \
>>> +         * It may also be the case that v->processor may change but the \
>>> +         * lock may be the same; this will succeed in that case. \
>>> +         */ \
>>> +        spin_lock##irq(lock, ## arg); \
>>> +        if ( likely(lock == per_cpu(schedule_data, cpu).schedule_lock) ) \
>>> +            return lock; \
>>> +        spin_unlock##irq(lock, ## arg); \
>>> +    } \
>>>   }
>> The readability of this (and others) would be much easier if the '\'
>> were aligned on the RHS and out of view of the main body.
> This depends on the fonts you use - in a mail reader using variable
> width fonts it reads much better the way I coded it. And while I
> realized that there are may cases where there is right alignment of
> these line continuations, I'm personally not in favor of this style,
> and since the coding style document doesn't say anything about it
> I used my personal preference...

But what we care about is how it looks in an editor.  I presume when 
you're actually coding you use a fixed-width font? :-)

  -George