lkml.org 
[lkml]   [2010]   [Sep]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 10/14] scsi: osd: fix device_register() error handling
    On 09/19/2010 02:55 PM, Vasiliy Kulikov wrote:
    > If device_register() fails then call put_device().
    > See comment to device_register.
    >
    > Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
    > ---
    > compile tested.
    >
    > drivers/scsi/osd/osd_uld.c | 4 +++-
    > 1 files changed, 3 insertions(+), 1 deletions(-)
    >
    > diff --git a/drivers/scsi/osd/osd_uld.c b/drivers/scsi/osd/osd_uld.c
    > index cefb2c0..3e0edc2 100644
    > --- a/drivers/scsi/osd/osd_uld.c
    > +++ b/drivers/scsi/osd/osd_uld.c
    > @@ -474,7 +474,7 @@ static int osd_probe(struct device *dev)
    > error = device_register(&oud->class_dev);
    > if (error) {
    > OSD_ERR("device_register failed => %d\n", error);
    > - goto err_put_cdev;
    > + goto err_put_device;
    > }
    >
    > get_device(&oud->class_dev);
    > @@ -482,6 +482,8 @@ static int osd_probe(struct device *dev)
    > OSD_INFO("osd_probe %s\n", disk->disk_name);
    > return 0;
    >
    > +err_put_device:
    > + put_device(&oud->class_dev);

    I'm not sure we can do this here. We might need to disregard the
    comment at device_register. Because this put_ will try to call the
    registered __release which will try to free the oud structure which
    has the ->class_dev embedded, and now we have a double free.

    But I will add a fat comment if all agree.

    I'm assuming that if the device_register has failed then we are not
    yet on any exposed system lists. (proof of we don't need to call
    device_unregister). Since we don't yet let anyone see this device
    we can go head and free it regardless of it's initialized ref-count
    == 1. The motivation here is to tear down the device without any
    possible users. Is that guaranteed? From my code audit it is.

    > err_put_cdev:
    > cdev_del(&oud->cdev);
    > err_put_disk:

    And I think device_register has a very bad API side effect with this put.
    If you are going to monitor all places that do not call put_device. Why
    not go to all places that do, and remove them and fix device_register.
    Do a majority vote. What is done more? put_device called or not called.

    Thanks
    Boaz


    \
     
     \ /
      Last update: 2010-09-19 17:35    [W:3.416 / U:1.160 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site