Commit 2ee7c922 authored Aug 09, 2010 by Oleg Nesterov Committed by Linus Torvalds Aug 09, 2010

sys_personality: remove the bogus checks in sys_personality()->__set_personality() path



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>

parent 5bf1d290

kernel/exec_domain.c

+5 −17

Original line number	Diff line number	Diff line
		@@ -134,23 +134,14 @@ unregister_exec_domain(struct exec_domain *ep)
		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;
		}