On 8/29/23 14:27, Warner Losh wrote:
> + if (put_user_s32(fd, target_fdp)) { > + return -TARGET_EFAULT; > + }I *think* this copy belongs in the parent? I think that it's copied out in both cases. For normal fork, this would be 0 for the pid. However, it appears to return the same FD to both the parent and child (see your next comment), so it should be in both paths. And even if it returned something different for parent and child (which seems unlikely given how the code is setup), we want to return the fd each one sees. So either way, I think this code is correct. It's really hard to follow the path of new process creation within the freebsd kernel. Agreed.
I think that the child never returns from do_fork. The child pid == 0 happens as part of do_fork or vm_forkproc or somesuch, but the new process definitely begins life at fork_return.
Therefore only the parent passes returns from fork1 to set *fdp. r~
