Hi Jan, It is possible that since I haven't done this wake up from user space, I have this problem. I want to know as to how you wake up the internal thread ? Is it thru a ioctl designed for the job ? Advance thanks, Pradeep On Sat, 9 Feb 2002, Jan Hudec wrote: > Hello, > > > I'd like to put to sleep or what ever a kernel module's function until a > > user space app generate an event in another function in the module. I'd > > like this function that have to sleep or what ever you say be reentrant. > > I've been trying to do this a whole month, so.... I need help or I'll > > lose my job :-D > > In what context this function runs? If in process, then it may never be > reentered with the same current (ie. in the same task - different pthread > thread has different current too). And it's the current that's inserted into > waitqueue. If it should run... well, you can only wait in process context > (kernel thread is a process context too). > > There can be any number of processes sleeping on one wait queue. One (global) > waitqueue for given type of events should suffice. All the tasks waiting for > it will wake up, one of them handles it, the others go back to sleep. > > To put a function to sleep, create a global wait queue head (via > DECLARE_WAIT_QUEUE_HEAD macro). Then the function that sleeps will simply use > the macro wait_event with &<this global wq head> as first arg and an expression > that yields true when the function should wake up as second argument. > Use wait_event_interruptible instead if you want to wake up on signal arrival > too. > > In function, where events are recieved, you record the relevant data somewhere > so the waiters can test them and simply wake_up(&<the global wq head>). > That will wake them up all, those concernced (you must solve relevant SMP races > et. al.) will handle it, the others will return to sleep. > > So far I can't see any problem. Maybe I missed your point. > -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ IRC Channel: irc.openprojects.net / #kernelnewbies Web Page: http://www.kernelnewbies.org/
