[Intel-wired-lan] [PATCH] igb: protect TX timestamping from API misuse

Miroslav Lichvar mlichvar at redhat.com
Tue Jun 20 12:55:52 UTC 2017


On Mon, Jun 19, 2017 at 01:30:43PM -0700, Cliff Spradlin wrote:
> HW timestamping can only be requested for a packet if the NIC is first
> setup via ioctl(SIOCSHWTSTAMP). If this step was skipped, then the igb
> driver still allowed TX packets to request HW timestamping. In this
> situation, the _IGB_PTP_TX_IN_PROGRESS flag was set and would never
> clear. This prevented any future HW timestamping requests to succeed.

Good catch!

This probably explains some weird cases I saw where HW timestamping
stopped working and the only thing that fixed it was to rmmod &&
modprobe the igb driver. I suspected a faulty HW and it's probably
just me messing with hwstamp_ctl at wrong time.

Thanks,

-- 
Miroslav Lichvar


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