On Thu, Sep 17, 2015 at 2:49 PM, Ian Kent <raven@xxxxxxxxxx> wrote:
> On Thu, 2015-09-17 at 11:48 +0800, Yu Ning wrote:
>> The default PTHREAD_COND_INITIALIZER initializer uses realtime clock,
>> we need to switch to use the monotic clock.
>>
>> Signed-off-by: Yu Ning <ning.yu@xxxxxxxxxx>
>> ---
>> lib/alarm.c | 13 ++++++++++++-
>> 1 file changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/lib/alarm.c b/lib/alarm.c
>> index 65a80ae..5b98b2d 100755
>> --- a/lib/alarm.c
>> +++ b/lib/alarm.c
>> @@ -23,7 +23,7 @@ struct alarm {
>> };
>>
>> static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
>> -static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
>> +static pthread_cond_t cond;
>> static LIST_HEAD(alarms);
>>
>> #define alarm_lock() \
>> @@ -212,6 +212,7 @@ int alarm_start_handler(void)
>> pthread_t thid;
>> pthread_attr_t attrs;
>> pthread_attr_t *pattrs = &attrs;
>> + pthread_condattr_t condattrs;
>> int status;
>>
>> status = pthread_attr_init(pattrs);
>> @@ -224,8 +225,18 @@ int alarm_start_handler(void)
>> #endif
>> }
>>
>> + status = pthread_condattr_init(&condattrs);
>> + if (status)
>> + fatal(status);
>> +
>> + pthread_condattr_setclock(&condattrs, CLOCK_MONOTONIC);
>> + pthread_cond_init(&cond, &condattrs);
>> +
>> status = pthread_create(&thid, pattrs, alarm_handler, NULL);
>>
>> + pthread_condattr_destroy(&condattrs);
>> + pthread_condattr_destroy(&cond);
>
> I don't think we can do this.
>
> The condition is used by the alarm_handler() for the duration of it's
> life so I don't think we can't destroy its attributes after thread
> creation.
>
> In fact I'm not sure we even need the pthread_condattr_destroy(&cond)
> but I'm not sure.
>
> Destroying the condition attributes (condattrs) OTOH must not affect any
> condition which it has been used to initialize so destroying that is
> fine.
>
> Let me have a closer look at this, maybe I've misunderstood what's going
> on, and report back later.
>
I think you are right, we shouldn't destroy the cond attrs, nor the cond
(and I used wrong function to destroy cond...) if the thread is successfully
created.
In fact I think we should do the cleanup at the end of the thread, however
since the thread is expected to live __forever__, maybe we can simply ignore
the cleanup.
>> +
>> if (pattrs)
>> pthread_attr_destroy(pattrs);
>>
>
>
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