On Tue, Jan 30, 2018 at 08:37:06PM +0000, Shahaf Shuler wrote:

Tuesday, January 30, 2018 11:40 AM, Adrien Mazarguil:

quoted

Unfortunately I didn't get a chance to review this patch before it was applied.
I'm not sure a stopped port is supposed to report events (interrupts). Will
applications expect them to occur at this point?

Why not?

Stopped port is still counted as attached. The fact the application stopped the packet receive on it doesn't mean it should not receive a sync events (such as the remove event).
async events, by definition, are not related to traffic being flows through the port. 

My comment is based on my understanding of rte_eth_dev_stop(), which is a
device (or port) is completely stopped, in a suspended state and no
interrupts shall occur, as a means for applications to temporarily not be
bothered by them until restarted.

Think about it that way: applications do not want to get interrupts
immediately after the device is initialized, because they might not be ready
to process them at this point. An explicit call to rte_eth_dev_start() tells
the PMD when it's OK to do so. The converse is rte_eth_dev_stop().

Stopping traffic can already be achieved by not polling from the application
side, calling rte_eth_dev_[rt]x_queue_stop() and/or toggling RX/TX
interrupts through rte_eth_dev_[rt]x_intr_enable(). rte_eth_dev_stop()
provides lower-level device control.

Perhaps documentation is not clear, however that's how LSC seems implemented
in all PMDs; it gets disabled after rte_eth_dev_stop() and one should
explicitly use rte_eth_link_get() to retrieve link status afterward. I think
RMV should behave similarly with rte_eth_dev_is_removed(). Adapting
fail-safe should be easier than modifying all the remaining PMDs.

quoted

In my opinion it's not a fix, as in, it doesn't address an issue introduced by the
mentioned patch whose behavior was correct.

It's probably too late to change it now and it does address an issue seen with
a use case involving this PMD, however I think the fail-safe PMD could as well
poll using the recently-added rte_eth_dev_is_removed() when it's aware
the underlying port is stopped instead of expecting interrupts.

--
Adrien Mazarguil
6WIND

-- 
Adrien Mazarguil
6WIND