From: Patrick McHardy <kaber@trash.net>
To: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Josip Loncaric <josip@lanl.gov>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH] net/sunrpc: fix time conversion error
Date: Tue, 02 Aug 2005 02:03:59 +0200 [thread overview]
Message-ID: <42EEB86F.1090808@trash.net> (raw)
In-Reply-To: <20050801225643.GA4285@us.ibm.com>
Nishanth Aravamudan wrote:
> On 01.08.2005 [15:11:48 -0600], Josip Loncaric wrote:
>
>>Line 589 of linux-2.6.11.10/net/sunrpc/svcsock.c is obviously wrong:
>>
>> skb->stamp.tv_usec = xtime.tv_nsec * 1000;
>>
>>To convert nsec to usec, one should divide instead of multiplying:
>>
>> skb->stamp.tv_usec = xtime.tv_nsec / 1000;
>>
>>The same bug could be present in the latest kernels, although I haven't
>>checked. This bug makes svc_udp_recvfrom() timestamps incorrect.
>
>
> Agreed, the conversion is wrong. I think the code is buggy period, as it
> accesses xtime without grabbing the xtime_lock first. Following patch
> should fix both issues.
>
> Description: This function incorrectly multiplies a nanosecond value by
> 1000, instead of dividing by 1000, to obtain a corresponding microsecond
> value. Fix the math. Also, the function incorrectly accesses xtime
> without using the xtime_lock. Fixed as well. Patch is compile-tested.
Depending on in which release you want this patch included, you might
want to redo it against Dave's net-2.6.14 tree. It includes a patch that
changes skb->stamp to an offset against a base timestamp.
Regards
Patrick
PS: I'll submit the patch to break compilation for unconverted users
ASAP.
next prev parent reply other threads:[~2005-08-02 0:04 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-08-01 21:11 Time conversion error in linux-2.6.11.10/net/sunrpoc/svcsock.c Josip Loncaric
2005-08-01 22:56 ` [PATCH] net/sunrpc: fix time conversion error Nishanth Aravamudan
2005-08-02 0:03 ` Patrick McHardy [this message]
2005-08-02 0:11 ` Nishanth Aravamudan
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