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SubjectRe: [PATCH] perf_event: fix error handling path
On 12/07/2010 05:51 PM, jovi zhang wrote:
> On Mon, Dec 6, 2010 at 9:59 AM, jovi zhang<bookjovi@gmail.com> wrote:
>> On Sun, Dec 5, 2010 at 8:29 PM, Thiago Farina<tfransosi@gmail.com> wrote:
>>>
>>> On Sat, Dec 4, 2010 at 1:19 AM,<bookjovi@gmail.com> wrote:
>>>> fix error handling path
>>>>
>>>> Signed-off-by: Jovi Zhang<bookjovi@gmail.com>
>>>> kernel/perf_event.c | 2 --
>>>> 1 files changed, 0 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/kernel/perf_event.c b/kernel/perf_event.c
>>>> index cb6c0d2..62f9e9d 100644
>>>> --- a/kernel/perf_event.c
>>>> +++ b/kernel/perf_event.c
>>>> @@ -1918,8 +1918,6 @@ static int get_callchain_buffers(void)
>>>> }
>>>>
>>>> err = alloc_callchain_buffers();
>>>> - if (err)
>>>> - release_callchain_buffers();
>>>
>>> Care to explain in the change log message? As I reader, is not clear
>>> to me what is wrong with this.
>>
>> Sorry, the description should be as:
>> fix error handling path. alloc_callchain_buffers() can return -ENOMEM,
>> in this time callchain_cpus_entries maybe is NULL, It will oops if
>> invoke release_callchain_buffers() when callchain_cpus_entries is
>> NULL.
>>
> I hope my understanding is right, is it?

One possible problem here is what if it returns an error other than
-ENOMEM, and the buffers do need to be released? Maybe you could change
the code to

err = alloc_callchain_buffers();
if (err != -ENOMEM)
release_callchain_buffers();


Currently, alloc_callchain_buffers cannot return any error code other
than -ENOMEM, but that might change in the future.

- Corey


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