Merge patch series "coredump: further cleanups"

Christian Brauner <brauner@kernel.org> says:

Continue reworking the coredump code so it's easier to follow and modify
in the future.

* Each method is moved into a separate helper.
* The cleanup code is simplified and unified.
* Entangle the dependency between the pipe coredump rate limiting and
  the common exit path.

It's likely that there'll be more.

* patches from https://lore.kernel.org/20250612-work-coredump-massage-v1-0-315c0c34ba94@kernel.org: (24 commits)
  coredump: add coredump_skip() helper
  coredump: avoid pointless variable
  coredump: order auto cleanup variables at the top
  coredump: add coredump_cleanup()
  coredump: auto cleanup prepare_creds()
  cred: add auto cleanup method
  coredump: directly return
  coredump: auto cleanup argv
  coredump: add coredump_write()
  coredump: use a single helper for the socket
  coredump: move pipe specific file check into coredump_pipe()
  coredump: split pipe coredumping into coredump_pipe()
  coredump: move core_pipe_count to global variable
  coredump: prepare to simplify exit paths
  coredump: split file coredumping into coredump_file()
  coredump: rename do_coredump() to vfs_coredump()
  selftests/coredump: make sure invalid paths are rejected
  coredump: validate socket path in coredump_parse()
  coredump: don't allow ".." in coredump socket path
  fs: move name_contains_dotdot() to header
  ...

Link: https://lore.kernel.org/20250612-work-coredump-massage-v1-0-315c0c34ba94@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>