• Linus Torvalds's avatar
    Merge tag 'v6.4/pidfd.file' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux · ec40758b
    Linus Torvalds authored
    Pull pidfd updates from Christian Brauner:
     "This adds a new pidfd_prepare() helper which allows the caller to
      reserve a pidfd number and allocates a new pidfd file that stashes the
      provided struct pid.
    
      It should be avoided installing a file descriptor into a task's file
      descriptor table just to close it again via close_fd() in case an
      error occurs. The fd has been visible to userspace and might already
      be in use. Instead, a file descriptor should be reserved but not
      installed into the caller's file descriptor table.
    
      If another failure path is hit then the reserved file descriptor and
      file can just be put without any userspace visible side-effects. And
      if all failure paths are cleared the file descriptor and file can be
      installed into the task's file descriptor table.
    
      This helper is now used in all places that open coded this
      functionality before. For example, this is currently done during
      copy_process() and fanotify used pidfd_create(), which returns a pidfd
      that has already been made visibile in the caller's file descriptor
      table, but then closed it using close_fd().
    
      In one of the next merge windows there is also new functionality
      coming to unix domain sockets that will have to rely on
      pidfd_prepare()"
    
    * tag 'v6.4/pidfd.file' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
      fanotify: use pidfd_prepare()
      fork: use pidfd_prepare()
      pid: add pidfd_prepare()
    ec40758b
fork.c 83.5 KB