[Intel-wired-lan] [PATCH] i40e: fix i40e_ptp_adjtime when given a negative delta

Bowers, AndrewX andrewx.bowers at intel.com
Sat Mar 2 00:08:49 UTC 2019


> -----Original Message-----
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces at osuosl.org] On
> Behalf Of Jacob Keller
> Sent: Monday, February 25, 2019 11:20 AM
> To: Intel Wired LAN <intel-wired-lan at lists.osuosl.org>
> Cc: Arnd Bergmann <arnd at arndb.de>
> Subject: [Intel-wired-lan] [PATCH] i40e: fix i40e_ptp_adjtime when given a
> negative delta
> 
> Commit 0ac30ce43323 ("i40e: fix up 32 bit timespec references",
> 2017-07-26) claims to be cleaning up references to 32-bit timespecs.
> 
> The actual contents of the commit make no sense, as it converts a call to
> timespec64_add into timespec64_add_ns. This would seem ok, if (a) the
> change was documented in the commit message, and (b)
> timespec64_add_ns supported negative numbers.
> 
> timespec64_add_ns doesn't work with signed deltas, because the
> implementation is based around iter_div_u64_rem. This change resulted in a
> regression where i40e_ptp_adjtime would interpret small negative
> adjustments as large positive additions, resulting in incorrect behavior.
> 
> This commit doesn't appear to fix anything, is not well explained, and
> introduces a bug, so lets just revert it.
> 
> Reverts: 0ac30ce43323 ("i40e: fix up 32 bit timespec references", 2017-07-26)
> Signed-off-by: Jacob Keller <jacob.e.keller at intel.com>
> ---
>  drivers/net/ethernet/intel/i40e/i40e_ptp.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

Tested-by: Andrew Bowers <andrewx.bowers at intel.com>




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