linux-kernel - Re: [PATCH 25/20] sysfs: Only support removing emtpy sysfs directories.

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Date:	Sun, 24 May 2009 14:59:38 +0200
From:	Kay Sievers <kay.sievers@...y.org>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	linux-kernel@...r.kernel.org, Tejun Heo <tj@...nel.org>,
	Cornelia Huck <cornelia.huck@...ibm.com>,
	linux-fsdevel@...r.kernel.org,
	"Eric W. Biederman" <ebiederm@...stanetworks.com>
Subject: Re: [PATCH 25/20] sysfs: Only support removing emtpy sysfs 
 directories.

On Sat, 2009-05-23 at 23:27 +0200, Kay Sievers wrote:
> On Sat, May 23, 2009 at 22:13, Eric W. Biederman <ebiederm@...ssion.com> wrote:
> > From: Eric W. Biederman <ebiederm@...ssion.com>
> >
> > I have looked and I have not found a single legitimate case today where
> > we remove sysfs directories with anything in them.  The only case I have
> > found to date was a bug.  It was a problem of ownership.  The files in
> > the directory where not owned by the directory itself.   Leaving open
> > the potential for double deletion of the directory contents.
> >
> > Signed-off-by: Eric W. Biederman <ebiederm@...stanetworks.com>
> 
> Sounds good to me. We should try that, and see if there was any valid
> use case we didn't think of, and if not, it's good to do what this
> patch does.

I get a bunch of warnings here. The question is if the users should be
fixed, the warning removed, and/or the auto-deletion added back?

I've added:
  -       WARN(dir_sd->s_dir.children,
  -               KERN_WARNING "sysfs: removing non-empty dir: %s\n",
  -               dir_sd->s_name);
  +       if (dir_sd->s_dir.children) {
  +               struct sysfs_dirent *sd;
  +
  +               WARN(dir_sd->s_dir.children,
  +                       KERN_WARNING "sysfs: removing non-empty dir: %s\n",
  +                       dir_sd->s_name);
  +               sd = dir_sd->s_dir.children;
  +               while (sd) {
  +                       printk(KERN_WARNING "%s/%s\n", dir_sd->s_name, sd->s_name);
  +                       sd = sd->s_sibling;
  +               }
  +       }

And get non-empty directories from CPU, SCSI, firmware_class, sound, block:
  sysfs: removing non-empty dir: state0
  state0/name
  state0/desc
  state0/latency
  state0/power
  state0/usage
  state0/time

  sysfs: removing non-empty dir: 0000:03:00.0
  0000:03:00.0/data
  0000:03:00.0/loading

  sysfs: removing non-empty dir: iosched
  iosched/quantum
  iosched/fifo_expire_sync
  iosched/fifo_expire_async
  iosched/back_seek_max
  iosched/back_seek_penalty
  iosched/slice_sync
  iosched/slice_async
  iosched/slice_async_rq
  iosched/slice_idle

  sysfs: removing non-empty dir: queue
  queue/nr_requests
  queue/read_ahead_kb
  queue/max_hw_sectors_kb
  queue/max_sectors_kb
  queue/scheduler
  queue/hw_sector_size
  queue/rotational
  queue/nomerges
  queue/rq_affinity
  queue/iostats

  sysfs: removing non-empty dir: 4:0:0:0
  4:0:0:0/queue_depth
  4:0:0:0/queue_type
  4:0:0:0/max_sectors

  sysfs: removing non-empty dir: host4
  host4/target4:0:0

  sysfs: removing non-empty dir: pcmC1D0c
  pcmC1D0c/pcm_class

  sysfs: removing non-empty dir: card1
  card1/id
  card1/number


Thanks,
Kay

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