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Subject[PATHC] remove a redundant variable in sys_prctl()
Date
Here's a re-send of a small patch I sent on Aug. 9.

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>
---

kernel/sys.c | 6 ++----
1 files changed, 2 insertions(+), 4 deletions(-)

--- linux-2.6.13-rc6-mm1-orig/kernel/sys.c 2005-08-19 19:21:25.000000000 +0200
+++ linux-2.6.13-rc6-mm1/kernel/sys.c 2005-08-21 01:30:03.000000000 +0200
@@ -1709,7 +1709,6 @@ asmlinkage long sys_prctl(int option, un
unsigned long arg4, unsigned long arg5)
{
long error;
- int sig;

error = security_task_prctl(option, arg2, arg3, arg4, arg5);
if (error)
@@ -1717,12 +1716,11 @@ asmlinkage long sys_prctl(int option, un

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);


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