On Tue, 2017-02-28 at 10:14 +0000, David Laight wrote: > From: Eric Dumazet > > Sent: 27 February 2017 22:35 > > On Mon, 2017-02-27 at 14:14 -0800, Stephen Hemminger wrote: > > > > > The original design (as Davem mentioned) was that IRQ's must be disabled > > > during device polling. If that was true, then the race above > > > would be impossible. > > > > I would love to see an alternative patch. > > Can you test for 'receive data available' after telling the NAPI > logic that you've finished? > You'd then need to force a reschedule. > > I think your proposed patch will do a reschedule if any packet arrives > during the receive processing, not just when one arrives right at the end. > You might want to 'unset' the reschedule flag before each check of the > receive ring. > > I also wonder about the cost of processing the MSI-X (I guess) interrupts > compared to the cost of posted PCIe writes to disable and/or mask the > interrupt generation. > Clearly you don't want to do PCIe reads.
Have you seen the mlx4 patch I provided ? Then, I did not want to review 100+ NAPI drivers and provide patches for them. This generic solution is basically free. Same number of atomic operations. Given it took more than 2 years to even spot the bug, I have no idea how people on netdev expect me to review all drivers. This is crazy.
