From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Monjalon <thomas@monjalon.net>
Subject: Re: ip_frag: handle MTU sizes not aligned to 8 bytes
Date: Thu, 22 Jun 2017 18:00:25 +0200
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Cc: dev@dpdk.org, "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
To: "Legacy, Allain (Wind River)" <allain.legacy@windriver.com>
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> > The rte_ipv4_fragment_packet API expects that the link/interface MTU value
> > passed in be divisible by 8 bytes.  Given the name of the parameter is
> > "mtu" rather than "frag_size" it is not necessarily the case that it will
> > be divisible by 8.  An MTU of 1500 happens to produce a max fragment size
> > of 1480 (1500 - sizeof(ipv4_hdr)) which is divisible by 8 but other MTU
> > values such as 1600 or 9000 do not produce values that are divisible by 8.
> > 
> > Unfortunately, the API checks that the frag_size value produced is
> > divisible by 8 with a call to RTE_ASSERT which is only enabled when the
> > RTE_LOG_LEVEL >= RTE_LOG_DEBUG.  In cases where the log level is set
> > normally the code silently continues and produces IP fragments that have
> > invalid fragment offset values.
> > 
> > An application may not have control over what MTU a user selects and rather
> > than have each application adjust the MTU to pass a suitable value to the
> > fragmentation API this change modifies the fragmentation API to handle
> > cases where the "mtu" argument is not divisible by 8 and automatically
> > adjust the internal "frag_size".
> > 
> > Signed-off-by: Allain Legacy <allain.legacy@windriver.com>
> 
> Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

Applied, thanks