Hello Michael thanks for replying, My comments are inline below On Wed, Apr 1, 2009 at 10:11 PM, Michael Blizek <michi1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > Hi! > > On 20:42 Wed 01 Apr , Devesh Sharma wrote: >> Hello list, >> >> Consider a case where I have a workqueue, a work is submitted to a it >> from some interrupt handler >> Lets say, some where in a code, it tries to get some semaphore to >> enter into a critical section, >> and fails to get it, sholud I still return from the work function by >> returning ERESTARTSYS? > > No, this is not a good idea. The work function which is called is expected to > return void. If you return ERESTARTSYS anyway, your function will not be > called again. So should I assume semaphores can not be used with workqueues? if used and down_trylock() is used then some kind of wait mechanism has to be used? Also what is the case with down_interruptible() is used? > > If your function is executed in workqueue context, it will be able to sleep and > it to wait for the semaphore, but it should not take too long, because it might > delay other tasks. In this case, you can set the workqueue up in a way that it > has its own threads and does not cause delays for other workqueue users. > > BTW: What is your reason for using semaphores? See > Documentation/mutex-design.txt Hmm...........this document talks about not to use mutexes with tasklet which clear my probable next question..:). I just wanted to know th feasibility of semaphores usage with workqueue also. > > -Michi > -- > programing a layer 3+4 network protocol for mesh networks > see http://michaelblizek.twilightparadox.com > > -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
