[Intel-gfx] [PATCH i-g-t v4 01/13] lib/sw_sync: Add helper functions for managing synchronization primitives

[Robert Foss]

On 2016-09-15 02:35 PM, Robert Foss wrote:
>
>
> On 2016-09-15 02:46 AM, Chris Wilson wrote:
>> On Wed, Sep 14, 2016 at 11:04:30AM -0400, robert.foss at collabora.com
>> wrote:
>>> +void sw_sync_timeline_inc(int fd, uint32_t count)
>>> +{
>>> +    uint32_t arg = count;
>>> +
>>> +    if (fd == 0)
>>> +        return;
>>
>> But fd = 0 is a valid fd, and might be a timeline somewhere.
>>
>> Did you mean count == 0 ?
>>
>> And even then (unless it is defined as an error condition in the kernel
>> ABI, and it should not be...) we should pass it through to the kernel.
>
> You're right, I'll change it in v5.
>
>>
>>> +    do_ioctl(fd, SW_SYNC_IOC_INC, &arg);
>>> +}
>>> +
>>
>>> +int sw_sync_wait(int fence, int timeout)
>>> +{
>>> +    struct pollfd fds;
>>> +    int ret;
>>> +
>>> +    fds.fd = fence;
>>> +    fds.events = POLLIN | POLLERR;
>>
>> POLLERR is always implied and doesn't need to be specified (it is
>> meaningless in .events).
>>
>> int sw_sync_wait(int fence, int timeout)
>> {
>> #if BEING_FANCY
>>     return poll(&(struct pollfd){fd, POLLIN}, 1, timeout);
>> #else
>>     struct pollfd pfd = { fd, POLLIN };
>>     return poll(&pfd, 1, timeout);
>> #endif
>> }
>>
>> Indentation has gone wrong, double check the whitespace.
>
> That is definitely nicer looking. I'll drop it in for v5.
>
>>
>>
>> How do fences operate after their timeline is closed? (Are they
>> automatically signaled, or do they persist and are signaled normally?) Is
>> there a test for using fences from a closed timeline (I was looking but
>> didn't notice one).
>
> I did some quick tests just to confirm, closing the timeline signals all
> of its fences.

Actually, my quick test was wrong. A fence is _not_ signaled on when its 
timeline has been closed.

So you would like to see a test that confirms that a fence on closed 
timeline is not signaled?


Rob.