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From: Oleg Nesterov on 28 May 2010 15:20
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(a)redhat.com>
---

kernel/exec_domain.c | 22 +++++-----------------
1 file changed, 5 insertions(+), 17 deletions(-)

--- 34-rc1/kernel/exec_domain.c~2_CLEANUP 2010-05-28 18:23:25.000000000 +0200
+++ 34-rc1/kernel/exec_domain.c 2010-05-28 20:07:48.000000000 +0200
@@ -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 in
{
unsigned int old = current->personality;

- if (personality != 0xffffffff) {
+ if (personality != 0xffffffff)
set_personality(personality);
- if (current->personality != personality)
- return -EINVAL;
- }

return old;
}

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