linux-os (Dick Johnson) wrote:
Every time somebody wants to rewrite a macro, they declare that the
previous one had some race condition. If, in fact, you have only
one DMA occurring from your device then no race is possible with
interruptible_sleep_on(). wait_event_interruptible() is the same thing
but with an additional access to some memory variable, possibly
causing a cache refill which means it might take more time.
This is not correct. Using interruptible_sleep_on, there is no way to
prevent the race where the condition being waited on happens between the
test to see if it has become true and calling interruptible_sleep_on.
wait_event_interruptible puts the caller into the wait queue before
testing the condition, which prevents the race.
interruptible_sleep_on is, with good reason, no longer recommended for use.
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from [email protected]
Home Page: http://www.roberthancock.com/
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