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* CRED: Fix __task_cred()'s lockdep check and banner commentDavid Howells2010-07-291-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix __task_cred()'s lockdep check by removing the following validation condition: lockdep_tasklist_lock_is_held() as commit_creds() does not take the tasklist_lock, and nor do most of the functions that call it, so this check is pointless and it can prevent detection of the RCU lock not being held if the tasklist_lock is held. Instead, add the following validation condition: task->exit_state >= 0 to permit the access if the target task is dead and therefore unable to change its own credentials. Fix __task_cred()'s comment to: (1) discard the bit that says that the caller must prevent the target task from being deleted. That shouldn't need saying. (2) Add a comment indicating the result of __task_cred() should not be passed directly to get_cred(), but rather than get_task_cred() should be used instead. Also put a note into the documentation to enforce this point there too. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Jiri Olsa <jolsa@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* CRED: Holding a spinlock does not imply the holding of RCU read lockSerge E. Hallyn2010-04-271-9/+5
| | | | | | | | | | | Change the credentials documentation to make it clear that the RCU read lock must be explicitly held when accessing credentials pointers in some other task than current. Holding a spinlock does not implicitly hold the RCU read lock. Signed-off-by: Serge Hallyn <serue@us.ibm.com> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
* CRED: DocumentationDavid Howells2008-11-141-0/+582
Document credentials and the new credentials API. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>