David Laight <[email protected]> writes: > From: Daniel Colascione >> Sent: 31 October 2018 19:33 > ... >> You can't do it today with kill. The idea that keeping a open file >> descriptor to a /proc/pid or a file within it prevents PID reuse is >> widespread, but incorrect. > > Is there a real good reason why that shouldn't be the case? > ie Holding a reference on the 'struct pid' being enough to stop reuse. > > A patch to do that would be more generally useful.
Holding an open file descriptor to /proc/pid is enough to prevent pid reuse problems. If a pid number is reused a new 'struct pid' is generated. There is not 'struct pid' reuse. So in solving this the kernel data structure you would need to hold onto is a 'struct pid'. It is just necessary to add an interface to sending signals to that 'struct pid' and not looking up the 'struct pid' again by number. Eric
