> > It's not duplication, it's increment/decrement of a counter. > > > > Look for functions with 'get' and 'put' in their names. > > AFAICT counter is f_count in struct file, updated by fget and fput. Yes, this is the counter I was speaking about. But to me the only way to increment/decrement this counter was either to duplicate an existing reference using dup/dup2, or to fork the process. This was wrong, and I'm glad I learned that. FTR: After taking a look at the kernel code, the ioctl syscall is implemented in ksys_ioctl[0], which calls fdget/fdput to get the struct fd, incrementing and decrementing the count. Thanks your help ! > > I haven't looked at the code - there's an outside chance that the driver > > isn't doing reference counting correctly. > > pi433 driver does not mess with struct file too much so I guess it should > be safe :) I'll take a closer look at the TODO and come back later with a patch. If there's nothing to do I'll remove it, otherwise I'll fix it. Cheers, Hugo [0] https://elixir.bootlin.com/linux/latest/source/fs/ioctl.c#L692 -- Hugo Lefeuvre (hle) | www.owl.eu.com 4096/ 9C4F C8BF A4B0 8FC5 48EB 56B8 1962 765B B9A8 BACA _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
