Re: [PATCH] getrusage sucks

[Claudio Scordino <cloud.of.andor@gmail.com>]

> You need to wrap this with a read_lock(&tasklist_lock) to be safe, I think.

Right. Probably this was the meaning also of Hua's mail. Sorry, but I didn't 
get it immediately.

So, what if I do as follows ? Do you see any problem with this solution ?

Many thanks,

              Claudio



diff --git a/kernel/sys.c b/kernel/sys.c
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1746,9 +1746,22 @@ int getrusage(struct task_struct *p, int

 asmlinkage long sys_getrusage(int who, struct rusage __user *ru)
 {
-       if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN)
-               return -EINVAL;
-       return getrusage(current, who, ru);
+        int res;
+        if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN) {
+                struct task_struct* tsk;
+                read_lock(&tasklist_lock);
+                tsk = find_task_by_pid(who);
+                if (tsk == NULL) {
+                        read_unlock(&tasklist_lock);
+                        return -EINVAL;
+                }
+                res = getrusage(tsk, RUSAGE_SELF, ru);
+                read_unlock(&tasklist_lock);
+                return res;
+        } else {
+                res = getrusage(current, who, ru);
+                return res;
+        }
 }

 asmlinkage long sys_umask(int mask)