lkml.org 
[lkml]   [2018]   [Mar]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH] coresight: use put_device() instead of kfree()
    From
    Date


    On Tuesday 27 March 2018 03:16 AM, Mathieu Poirier wrote:
    > drivers/hwtracing/coresight/coresight.c
    > On 18 March 2018 at 01:38, Arvind Yadav <arvind.yadav.cs@gmail.com> wrote:
    >> Never directly free @dev after calling device_register(), even
    >> if it returned an error. Always use put_device() to give up the
    >> reference initialized.
    >>
    >> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
    >> ---
    >> drivers/hwtracing/coresight/coresight.c | 8 ++++----
    >> 1 file changed, 4 insertions(+), 4 deletions(-)
    >>
    >> diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
    >> index 389c4ba..132dfbc 100644
    >> --- a/drivers/hwtracing/coresight/coresight.c
    >> +++ b/drivers/hwtracing/coresight/coresight.c
    >> @@ -1026,8 +1026,10 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
    >> dev_set_name(&csdev->dev, "%s", desc->pdata->name);
    >>
    >> ret = device_register(&csdev->dev);
    >> - if (ret)
    >> - goto err_device_register;
    >> + if (ret) {
    >> + put_device(&csdev->dev);
    >> + goto err_kzalloc_csdev;
    >> + }
    >>
    >> mutex_lock(&coresight_mutex);
    >>
    >> @@ -1038,8 +1040,6 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
    >>
    >> return csdev;
    >>
    >> -err_device_register:
    >> - kfree(conns);
    > Apologies for the late reply, I was travelling.
    >
    > I suggest to simply replace kfree() with put_device() in order to
    > concentrate the error handling code in the same area and make sure
    > that memory allocated for @conns and @refcnts is freed.
    >
    > Thanks,
    > Mathieu

    If you will see the comment for device_register(drivers/base/core.c)
    there is mentioned that 'NOTE: _Never_ directly free @dev
    after calling this function, even if it returned an error!
    Always use put_device() to give up the reference initialized
    in this function instead.
    Here put_device() will decrement the last reference and then
    free the memory by calling dev->release. Internally
    put_device() -> kobject_put() -> kobject_cleanup() which is
    responsible to call 'dev -> release' and also free other kobject
    resources. we should always avoid kfree() if device_register()
    returned an error. Otherwise it'll not do clean up of other
    kobject resources.

    ~arvind
    >> err_kzalloc_conns:
    >> kfree(refcnts);
    >> err_kzalloc_refcnts:
    >> --
    >> 2.7.4
    >>

    \
     
     \ /
      Last update: 2018-03-27 04:31    [W:3.061 / U:0.088 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site