Monday, April 9, 2018 11:28 AM, Nélio Laranjeiro: > Subject: Re: [PATCH] net/mlx5: fix link status initialization > > On Sun, Apr 08, 2018 at 01:09:27PM +0000, Shahaf Shuler wrote: > > Thursday, April 5, 2018 9:51 AM, Nélio Laranjeiro: > > > Subject: Re: [PATCH] net/mlx5: fix link status initialization > > > > > > On Thu, Apr 05, 2018 at 05:35:57AM +0000, Shahaf Shuler wrote: > > > > Wednesday, April 4, 2018 3:11 PM, Nélio Laranjeiro: > > > > > Subject: Re: [PATCH] net/mlx5: fix link status initialization > > > > > > > > > > On Wed, Apr 04, 2018 at 09:58:33AM +0000, Shahaf Shuler wrote: > > > > > > Wednesday, April 4, 2018 10:30 AM, Nélio Laranjeiro: > > > > > > > Subject: Re: [PATCH] net/mlx5: fix link status > > > > > > > initialization > > > > > > > > > > > > > > On Tue, Apr 03, 2018 at 07:48:17AM +0300, Shahaf Shuler wrote: > > > > [..] > > > > > > > > > > > > According to your analysis, this is only necessary when the LCS > > > > > is configured in the device. Why not adding this call to > > > > > mlx5_dev_interrupt_handler_install() which is responsible to > > > > > install the LCS callback. > > > > > > > > I think it is good practice whether or not LSC is set. > > > > The link status should be initialized to the correct value after the > > > > probe. > > > > > > There is no guarantee the link will be accurate, at probe time the > > > link may be up so internal information has a status up with a speed with > this patch. > > > The application probes a second port, in the mean time the link of > > > the first port goes down, the interrupt is still not installed and > > > the internal status becomes wrong (still up whereas the port is down). > > > > > > Finally at start, the device installs the handler, but the link is > > > still down whereas internally it is up, the application will call > > > rte_eth_link_get_nowait() which will directly copy the wrong > > > internal status to the application. > > > > This is not correct. > > Using Verbs, the async_fd on which link status interrupts are reported is > created on probe. > > Even if the interrupt handler is not installed, interrupts still > > trigger on this fd. They will be processed when the interrupt handler > > will be installed as part of the port start. > > So in fact you have the whole trace on the link status changes waiting > > to be processed upon port start. > > Right, but in such case, this patch still does not solves the issue. > Until the dev_start() is called, the link may be inconsistent with the real > status. > > example: > > pci_probe --> link is up. > leaving pci probe, the link goes downs --> internally the PMD has a link up. > > Until the dev_start() is called any call to rte_eth_link_get_nowait() will > copy > the internal PMD status which is not accurate. > > From this point, the issue seems to fully come from > rte_eth_link_get_nowait() which should not make any copy until the port is > not started, until then the link may be inconsistent between the driver and > the device.
Right. However fixing it only on the ethdev layer is not enough. Assume the link was up from the beginning. For the case were the call for rte_eth_link_get_nowait happens only after the port start, the link will still be wrong as it will be reported as down (and no interrupt to fix it). So to summarize I plan to have this patch (with modification of the wait_to_complete) along with another fix for ethdev. Do we have an agreement? > > Regards, > > -- > Nélio Laranjeiro > 6WIND