CRED: Fix RCU warning due to previous patch fixing __task_cred()'s checks
authorDavid Howells <dhowells@redhat.com>
Wed, 4 Aug 2010 15:59:14 +0000 (16:59 +0100)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 4 Aug 2010 18:17:10 +0000 (11:17 -0700)
commit694f690d27dadccc8cb9d90532e76593b61fe098
treeea641e53ae530d0d3708fbfcab8109cc5e840d21
parente75aa85892b2ee78c79edac720868cbef16e62eb
CRED: Fix RCU warning due to previous patch fixing __task_cred()'s checks

Commit 8f92054e7ca1 ("CRED: Fix __task_cred()'s lockdep check and banner
comment") fixed the lockdep checks on __task_cred().  This has shown up
a place in the signalling code where a lock should be held - namely that
check_kill_permission() requires its callers to hold the RCU lock.

Fix group_send_sig_info() to get the RCU read lock around its call to
check_kill_permission().

Without this patch, the following warning can occur:

  ===================================================
  [ INFO: suspicious rcu_dereference_check() usage. ]
  ---------------------------------------------------
  kernel/signal.c:660 invoked rcu_dereference_check() without protection!
  ...

Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/signal.c