>> In the original code of video_open() there are two small bugs: >> (1) the counter of the module is not incremented _before_ the >> file->f_op->open(inode,file) function call, but only before >> the vfl->open() one. >This isn't a bug. fops_get+put handles the module reference counting. Oops, you are right. I completely forgot it..:-) >> (2) the increment of the variable vfl->users is incoherent with the >> decrement of the same variable in the function video_release(). >> A brief analysis of the source code and of the patch reveals >> that it is so, but i will not enter into details. > Please go into details, IMHO the current code is fine. The fact is that I am writing a driver for my webcam. So I thought to use the field "users" of the struct video_device* to keep track of the number of users that are accessing to the V4L device at a time. For some reasons some problems occurred with that counter after a series of open and release calls (using the new interface), so i tried to search for some bugs in videodev.c (if they eventually existed). I found that in the function video_open() a vfl->users++ instruction is never reached, in case of success of the file->f_op->open(inode,file) call. On the contrary, vfl->users is always decremented in video_release() using both the new and the old interface. Therefore vfl->users can assume negative values... However I may be wrong.. Thank you, Luca Risolia.
