[PATCH 0/2] userns: clean up dead code on error paths

[Tao Cui <cui.tao@linux.dev>]

From: Tao Cui <cuitao@kylinos.cn>

Two small cleanups on the create_user_ns() and map_write() error
paths.  Both remove code that provably cannot have an effect; no
behavior change.

  user_namespace.c:164-167: the key_put() at fail_keyring has been
  dead since it was copy-pasted from free_user_ns() in 2016
  (dbec28460a89); persistent_keyring_register is only ever assigned
  lazily from key_get_persistent(), long after create_user_ns().

  user_namespace.c:1110-1112: the map clearing at the out: label of
  map_write() only ever zeroes an already-zero map; the destination
  map is untouched on every error path, and a second write to a
  mapped namespace is rejected before parsing.

Compile-tested and A/B-tested on next-20260827: identical behavior
on vanilla and patched kernels for single-write map failures,
recovery writes and 300 rounds of userns create/destroy.

Tao Cui (2):
  userns: remove dead key_put() on the create_user_ns() error path
  userns: don't clear the install target map on map_write() failure

 kernel/user_namespace.c | 6 ------
 1 file changed, 6 deletions(-)

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2.43.0