sys_personality: remove the bogus checks in sys_personality()->__set_personality...
Oleg Nesterov [Tue, 10 Aug 2010 00:20:30 +0000 (17:20 -0700)]
Cleanup, no functional changes.

- __set_personality() always changes ->exec_domain/personality, the
  special case when ->exec_domain remains the same buys nothing but
  complicates the code. Unify both cases to simplify the code.

- The -EINVAL check in sys_personality() was never right. If we assume
  that set_personality() can fail we should check the value it returns
  instead of verifying that task->personality was actually changed.

  Remove it. Before the previous patch it was possible to hit this case
  due to overflow problems, but this -EINVAL just indicated the kernel
  bug.

OTOH, probably it makes sense to change lookup_exec_domain() to return
ERR_PTR() instead of default_exec_domain if the search in exec_domains
list fails, and report this error to the user-space.  But this means
another user-space change, and we have in-kernel users which need fixes.
For example, PER_OSF4 falls into PER_MASK for unkown reason and nobody
cares to register this domain.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Wenming Zhang <wezhang@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/exec_domain.c

index dd62f8e..0dbeae3 100644 (file)
@@ -134,23 +134,14 @@ unregister:
        return 0;
 }
 
-int
-__set_personality(unsigned int personality)
+int __set_personality(unsigned int personality)
 {
-       struct exec_domain      *ep, *oep;
-
-       ep = lookup_exec_domain(personality);
-       if (ep == current_thread_info()->exec_domain) {
-               current->personality = personality;
-               module_put(ep->module);
-               return 0;
-       }
+       struct exec_domain *oep = current_thread_info()->exec_domain;
 
+       current_thread_info()->exec_domain = lookup_exec_domain(personality);
        current->personality = personality;
-       oep = current_thread_info()->exec_domain;
-       current_thread_info()->exec_domain = ep;
-
        module_put(oep->module);
+
        return 0;
 }
 
@@ -192,11 +183,8 @@ SYSCALL_DEFINE1(personality, unsigned int, personality)
 {
        unsigned int old = current->personality;
 
-       if (personality != 0xffffffff) {
+       if (personality != 0xffffffff)
                set_personality(personality);
-               if (current->personality != personality)
-                       return -EINVAL;
-       }
 
        return old;
 }