Hi Greg, Hi Yann, I have been actually more naive by implementing it this way (led on by ldd3, page 176). I have the issue for an FPGA board and reconfiguration. Basically if a program has control of the FPGA it does want the FPGA do its computations, without another program changing the design loaded onto the FPGA. For the time being I will settle on the user opening the device to be smart enough to not duplicate the fd. But I think there are usecases for the requested feature. regards Malte On 04/03/15 18:38, Yann Droneaud wrote: > Hi Greg, > > Le mercredi 04 mars 2015 à 10:11 -0800, Greg KH a écrit : >> On Wed, Mar 04, 2015 at 06:59:04PM +0100, Yann Droneaud wrote: >>> Hi, >>> >>> I have a device and I have to write a driver that exposes the >>> following three operations to kernel modules AND to userspace >>> programs: >> <snip> >> >> Why? > I'm trying to improve the current driver for this device to allow the > lock to be released when userspace program owning the lock is killed. > >> What type of device is this? > It's a device with some kind of over complicated mailbox. > > A userspace program is supposed to feed the mailbox with multiple > commands and no other userspace program should be allowed to play with > the device during that time. > >> And who is asking you to do this homework assignment? >> > It's not a homework assignment. It's not even something a little penguin > ask me to do. > > I was so sure I could map the semaphore sematics to open() and close() > and use that file descriptor to represent the lock that I feel terribly > sorry for not being able to do so. > > (At one point I felt like I was fighting against 40 years of Unix, and > such a fight is not going to be won by myself :) > > So I'm back to step 0 and looking for a way to be able to release a > lock in case of a userspace program is killed. > >> good luck, >> > Thanks :) > > Regards. > _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
