workqueues - how to use them correctly

[Arun KS]

Hello Roshan,

On Tue, Feb 10, 2015 at 2:20 PM, Roshan A <roshan.len at gmail.com> wrote:
>
> hi all,
>
> My question is regarding the correct use of workqueues. I have a
> driver which queues a work item in the interrupt handler. The bottom
> half function ( the workitem -function ) does have proper locking (
> mutex ) in place for atomicity.
>
> With this setup, since the interrupts are enabled, it's possible to
> have a scenario where, when one workitem is being executed, another
> can be queued up, which results in the workitems being executed in
> parallel, however since there is a mutex, one thread will sleep.
>
> is this particular scenario considered bad or discouraged ?

This should not happen if you are using the same work item.
All workqueues are now non-reentrant - any work item is guaranteed to
be executed by at most one worker system-wide at any given time.

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/kernel/workqueue.c?id=dbf2576e37da0fcc7aacbfbb9fd5d3de7888a3c1

Thanks,
Arun
>
>
> Thank you,
> -Roshan
>
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