lkml.org 
[lkml]   [2013]   [Nov]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRE: [PATCH] devres: Freeing the drs after all release() are called
Date


> -----Original Message-----
> From: Tejun Heo [mailto:htejun@gmail.com] On Behalf Of tj@kernel.org
> Sent: Thursday, November 07, 2013 8:30 AM
> To: Liu, Chuansheng
> Cc: Greg KH; dmitry.torokhov@gmail.com; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH] devres: Freeing the drs after all release() are called
>
> Hello, Liu.
>
> On Thu, Nov 07, 2013 at 12:27:56AM +0000, Liu, Chuansheng wrote:
> > The driver code is as below:
> > _INIT() {
> >
> > A = devm_kzalloc();
> > B= devm_request_threaded_irq(isr_handler);
> > C = devm_kzalloc();
> > }
> >
> > When driver _EXIT, the devres_release_all () will be called.
> > The C will be kfreed before B, but when freeing irq B, the pending isr_handler()
> possibly
> > will access the memory B which has been freed.
> > Then the memory corruption occurred.
> >
> > This patch can solve this scenario.
>
> Isn't the bug there IRQ being requested before all its resources are
> allocated? The proposed change just masks the underlying issue or
> incorrectly ordered operations.
Yes, I knew I can put the code always like below:
A = devm_kzalloc();
C = devm_kzalloc();
...
B= devm_request_threaded_irq(isr_handler);

But, the above is just one simple coding prototype, if there are many calling:
E -- > F -- > D -- >... then to devm_kzalloc().

To be honest, it will make code too hard to always adapt the rule?
And I trying to find out every potential devm_kzalloc() before irq requesting.


\
 
 \ /
  Last update: 2013-11-07 02:21    [W:0.057 / U:6.460 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site