October 2017
Intermediate to advanced
586 pages
14h 8m
English
Content preview from Linux Device Drivers Development
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Work queues
Added since Linux kernel 2.6, the most used and simple deferring mechanism is the work queue. It is the last one we will talk about in this chapter. As a deferring mechanism, it takes an opposite approach to the others we've seen, running only in a pre-emptible context. It is the only choice when you need to sleep in your bottom half (I will explain what a bottom half is later in the next section). By sleep, I mean process I/O data, hold mutexes, delay, and all the other tasks that may lead to sleep or move the task off the run queue.
Keep in mind that work queues are built on top of kernel threads, and this is the reason why I decided not to talk about the kernel thread as a deferring mechanism at all. However, there are two ...