Am 13.01.2015 um 10:04 schrieb Maarten Lankhorst:
Op 13-01-15 om 10:36 schreef Jammy Zhou:
When the timeout value passed to reservation_object_wait_timeout_rcu
is zero, no wait should be done if the fences are not signaled.
Return '1' for idle and '0' for busy if the specified timeout is '0'
to keep consistent with the case of non-zero timeout.
v2: call fence_put if not signaled in the case of timeout==0
Looks more sane, but where do you need this?
The rational is that we want a single function to call from the driver
no matter what timeout we have and get a zero if the call timed out and
a non zero value otherwise.
When we called reservation_object_wait_timeout_rcu with a timeout of
zero we got a return value of zero as well independent of whether or not
the fences were signaled. That behavior looked inconsistent and Jammy is
trying to fix this with this patch.
We could of course do the check in the calling code as well, but to me
it rather looked like the calling convention of
reservation_object_wait_timeout_rcu should be thought over one more time.
Either calling it with timeout=0 is invalid and the driver needs to call
reservation_object_test_signaled_rcu directly instead or we apply this
patch or something similar to get an useful behavior in the case of
timeout=0.
Regards,
Christian.
~Maarten
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