Re: [PATCH] trace: Fix incorrect number of pages used for trace metadata

[Igor Druzhinin <igor.druzhinin@citrix.com>]

Checked that.

Tested-by: Igor Druzhinin <igor.druzhinin@citrix.com>

On 30/09/16 17:12, George Dunlap wrote:
> On 30/09/16 17:04, Igor Druzhinin wrote:
>> On 30/09/16 15:46, George Dunlap wrote:
>>> On 29/09/16 14:53, Igor Druzhinin wrote:
>>>> As long as t_info_first_offset is calculated in uint32_t offsets we
>>>> need to
>>>> multiply it by sizeof(uint32_t) in order to get the right number of
>>>> pages
>>>> for trace metadata. Not doing that makes it impossible to read the trace
>>>> buffer correctly from userspace for some corner cases.
>>>>
>>>> Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
>>>
>>> Hmm, looks like we actually want to revert this c/s fbf96e6, "xentrace:
>>> correct formula to calculate t_info_pages".  But that one was presumably
>>> written (and Acked by me) because the variable name there,
>>> t_info_first_offset, is confusing.
>>>
>>> The other mistake in fbf96e6 is that before t_info_words was actually
>>> denominated in words; but after it's denominated in bytes (which is
>>> again confusing).
>>>
>>> What about something like the attached instead?  This should fix your
>>> problem while making the code clearer.
>>>
>>>  -George
>>>
>>>
>>
>> Reviewed-by: Igor Druzhinin <igor.druzhinin@citrix.com>
>
> Thanks.  Any chance I could get a Tested-by as well? :-)
>
>  -George
>

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