CODEWITHSUNDEEP
linuxlinux-kernellinux-device-driver
Ian Vaughan
Ian Vaughan

Reputation: 21321

Tell if device driver timeout has occured with wait_event_interruptible_timeout

Within my device driver, I am using wait_event_interruptible_timeout. How can I tell if a timeout has occurred? The macro only returns errorcode on interrupts but timeout is not an interrupt so "0" is returned.

Edit: not sure on how to tell if timeout occurred, but condition wont be set, so that sounds like the answer.

Upvotes: 3

Views: 2649

Answers (1)

Rakis
Rakis

Reputation: 7864

I ran into the same confusing issue a couple of weeks ago after reading the description of that function in Linux Device Drivers, Third Edition. Upon reading the comments for the various wait functions in a current kernel source tree, however, I found that the API has changed since the book was published. Newer kernels (at least 2.6.34+ and probably quite a bit further back than that), return the remaining number of jiffies to the timeout instead of an error code. So, a zero return value indicates the timeout occurred and any non-zero value should indicate a successful wakeup via the event condition. The comments in include/linux/wait.h provide a good description of the new API.

Upvotes: 4

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