From: Igor Druzhinin <igor.druzhinin@citrix.com>
To: George Dunlap <george.dunlap@citrix.com>, xen-devel@lists.xen.org
Cc: george.dunlap@eu.citrix.com,
Andrew Cooper <Andrew.Cooper3@citrix.com>,
Olaf Hering <olaf@aepfle.de>, Jan Beulich <JBeulich@suse.com>
Subject: Re: [PATCH] trace: Fix incorrect number of pages used for trace metadata
Date: Tue, 4 Oct 2016 10:59:48 +0100 [thread overview]
Message-ID: <28d7ebd8-d6cf-a6ff-38f1-6ef2f1a7c96e@citrix.com> (raw)
In-Reply-To: <66e8cec9-8db9-b413-395a-daa4df8b2c5f@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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prev parent reply other threads:[~2016-10-04 9:59 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-29 13:53 [PATCH] trace: Fix incorrect number of pages used for trace metadata Igor Druzhinin
2016-09-30 14:46 ` George Dunlap
2016-09-30 14:48 ` Andrew Cooper
2016-09-30 14:48 ` George Dunlap
2016-09-30 16:04 ` Igor Druzhinin
2016-09-30 16:12 ` George Dunlap
2016-10-04 9:59 ` Igor Druzhinin [this message]
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