[PATCH] remove a redundant variable in sys_prctl()

The patch removes a redundant variable `sig' from sys_prctl().

For some reason, when sys_prctl is called with option == PR_SET_PDEATHSIG
then the value of arg2 is assigned to an int variable named sig.  Then sig
is tested with valid_signal() and later used to set the value of
current->pdeath_signal .

There is no reason to use this intermediate variable since valid_signal()
takes a unsigned long argument, so it can handle being passed arg2
directly, and if the call to valid_signal is OK, then we know the value of
arg2 is in the range zero to _NSIG and thus it'll easily fit in a plain int
and thus there's no problem assigning it later to current->pdeath_signal
(which is an int).

The patch gets rid of the pointless variable `sig'.
This reduces the size of kernel/sys.o in 2.6.13-rc6-mm1 by 32 bytes on my
system.

Patch has been compile tested, boot tested, and just to make damn sure I
didn't break anything I wrote a quick test app that calls
prctl(PR_SET_PDEATHSIG ...) with the entire range of values for a
unsigned long, and it behaves as expected with and without the patch.

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/kernel/sys.c b/kernel/sys.c
index 0bcaed6..c80412b 100644 (file)
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1711,7 +1711,6 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
                          unsigned long arg4, unsigned long arg5)
 {
        long error;
-       int sig;
 
        error = security_task_prctl(option, arg2, arg3, arg4, arg5);
        if (error)
@@ -1719,12 +1718,11 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
 
        switch (option) {
                case PR_SET_PDEATHSIG:
-                       sig = arg2;
-                       if (!valid_signal(sig)) {
+                       if (!valid_signal(arg2)) {
                                error = -EINVAL;
                                break;
                        }
-                       current->pdeath_signal = sig;
+                       current->pdeath_signal = arg2;
                        break;
                case PR_GET_PDEATHSIG:
                        error = put_user(current->pdeath_signal, (int __user *)arg2);