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

[Chris Wilson]

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.

> +	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.


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).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre