Re: [PATCH] protect migration/%d etc from sched_setaffinity

[Joe Korty <joe.korty@ccur.com>]

On Thu, Jul 31, 2003 at 04:17:03PM -0700, Andrew Morton wrote:
> Joe Korty <joe.korty@ccur.com> wrote:
> >
> > I'd like to be able to write shell scrips that operate on the set of
> > /proc/[0-9]* without having to know which of the ever-changing list
> > of processes need to be avoided and which not.
> 
> Like this?
> 
> #!/bin/sh
> 
> #
> # can_set_affinity pid
> #
> can_set_affinity()
> {
> 	if [ "$(cat /proc/$1/maps)" != "" ]
> 	then
> 		return 0
> 	fi
> 	if head -1 /proc/$1/status | egrep "events|migration"
> 	then
> 		return 1
> 	else
> 		return 0
> 	fi
> }
> 
> if can_set_affinity $1
> then
> 	echo can set affinity of pid $1
> else
> 	echo cannot set affinity of pid $1
> fi


Good stuff.  I reduced it to (having trouble easily reading the original
output):

    name=$(head -1 /proc/$1/status | awk '{print $2}')
    echo -n '[' $1 '] ' $name ' '
    if [ "$(cat /proc/$1/maps)" == "" ]
    then
	    echo SAFE
    else
	    echo changeable
    fi

It catches all those that need catching, plus denies changes to some
daemons that could survive sched_setaffinity: khubd, kirqd, pdflush*,
kswapd0, scsi_eh_[01], ahc_dv_[01], kseriod, and kjournald*.

Joe