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SubjectRe: [PATCH] staging: comedi: add error handling for vmap
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On 14/06/18 08:57, Zhouyang Jia wrote:
> Hi,
>
> I reported this bug since more than 90% callsites of vmap are
> well handled in kernel. The caller function __comedi_buf_alloc
> has no return value, so I don't know how the error is handled in
> its caller.
>
> I believe there would be a better error handling method, but I
> have limited domain knowledge, so I'm sorry I can't help here.
>
> Thanks for your kind reply.
>
> Best,
> Zhouyang

__comedi_buf_alloc is just a helper function factored out of, and called
by comedi_buf_alloc. __comedi_buf_alloc does not clean up after itself
on error because it expects comedi_buf_alloc to detect the error and
call __comedi_buf_free to clean up any partially allocated mess:

__comedi_buf_alloc(dev, s, n_pages);
if (!async->prealloc_buf) {
/*
* [This is not the actual comment in the code!]
*
* Error occured in __comedi_buf_alloc().
* Buffer may be partially allocated.
* Call __comedi_buf_free() to clean it up.
*/
__comedi_buf_free(dev, s);
return -ENOMEM;
}

>
>
>
> 2018-06-12 19:50 GMT+08:00 Dan Carpenter <dan.carpenter@oracle.com
> <mailto:dan.carpenter@oracle.com>>:
>
> On Tue, Jun 12, 2018 at 11:25:35AM +0800, Zhouyang Jia wrote:
> > When vmap fails, the lack of error-handling code may
> > cause unexpected results.
> >
> > This patch adds error-handling code after calling vmap.
> >
>
> Again, this is not error handling, this is just an error message.  This
> error condition is handled in the caller.
>
> regards,
> dan carpenter
>
>
>


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