Messages in this thread Patch in this message | | | Date | Fri, 21 Apr 2006 12:05:13 +0200 | From | "Claudio Scordino" <> | Subject | Re: [PATCH] Extending getrusage |
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> > I'd be reluctant to support this change without a compelling description of > > why we actually want it. > > It offers nothing that isn't available elsewhere (I think), except more > cheaply. It also has the potential to be multiplatform one day. Right now to > get the CPU usage of a random pid, one has to implement the equivalent of > /proc/ parsing for each platform. > > If at least Linux did 'getrusage for foreign pid', that would clean up > things up somewhat already. > > It might even mean a 'portable top', and who knows, more unixes might > follow. > > I for one would save work having a getrusage that does this. > > Bert
Exactly! My modification was meant to add the possibility of having usage information about another process at user level.
Recently, while writing some code at user level, I needed a fast way to have such information about another process. I wanted to use the getrusage syscall, then I found out that the current implementation does not allow to get information about another process. Therefore, I proposed my patch.
As Bert said, it offers nothing that isn't available elsewhere, but more cheaply.
This patch with the changes that you asked me follows.
Thanks,
Claudio
Signed-off-by: Claudio Scordino <cloud.of.andor@gmail.com> diff -uprN linux-2.6.16.9/kernel/sys.c linux-2.6.16.9-new/kernel/sys.c --- linux-2.6.16.9/kernel/sys.c 2006-04-19 02:10:14.000000000 -0400 +++ linux-2.6.16.9-new/kernel/sys.c 2006-04-21 05:53:16.000000000 -0400 @@ -1765,11 +1765,30 @@ int getrusage(struct task_struct *p, int return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0; }
+/* who can be RUSAGE_SELF, RUSAGE_CHILDREN or a valid pid */ asmlinkage long sys_getrusage(int who, struct rusage __user *ru) { - if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN) - return -EINVAL; - return getrusage(current, who, ru); + struct rusage r; + struct task_struct *tsk = current; + read_lock(&tasklist_lock); + if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN) { + if (who <= 0) + goto bad; + tsk = find_task_by_pid(who); + if (tsk == NULL) + goto bad; + if ((tsk != current) && security_ptrace(current, tsk)) + goto bad; + /* current can get info about tsk */ + who = RUSAGE_SELF; + } + k_getrusage(tsk, who, &r); + read_unlock(&tasklist_lock); + return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0; + +bad: + read_unlock(&tasklist_lock); + return tsk ? -EPERM : -EINVAL; }
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