* Michael Kerrisk:
> SYNOPSIS
> int pidfd_send_signal(int pidfd, int sig, siginfo_t info,
> unsigned int flags);
This probably should reference a header for siginfo_t.
> ESRCH The target process does not exist.
If the descriptor is valid, does this mean the process has been waited
for? Maybe this can be made more explicit.
> The pidfd_send_signal() system call allows the avoidance of race
> conditions that occur when using traditional interfaces (such as
> kill(2)) to signal a process. The problem is that the traditional
> interfaces specify the target process via a process ID (PID), with
> the result that the sender may accidentally send a signal to the
> wrong process if the originally intended target process has termi‐
> nated and its PID has been recycled for another process. By con‐
> trast, a PID file descriptor is a stable reference to a specific
> process; if that process terminates, then the file descriptor
> ceases to be valid and the caller of pidfd_send_signal() is
> informed of this fact via an ESRCH error.
It would be nice to explain somewhere how you can avoid the race using
a PID descriptor. Is there anything else besides CLONE_PIDFD?
> static
> int pidfd_send_signal(int pidfd, int sig, siginfo_t *info,
> unsigned int flags)
> {
> return syscall(__NR_pidfd_send_signal, pidfd, sig, info, flags);
> }
Please use a different function name. Thanks.
