Re: [PATCH v1] mac80211_hwsim: add concurrent channels scanning support over virtio

On Thu, 2021-05-06 at 14:11 -0700, Weilun Du wrote:

On Thu, May 6, 2021 at 11:19 AM Johannes Berg [off-list ref] wrote:

quoted

On Thu, 2021-05-06 at 11:05 -0700, Weilun Du wrote:

quoted

This fixed the crash when setting channels to 2 or more when
communicating over virtio.

Interesting, I thought I was probably the only user of virtio? :)

johannes

Hi Johannes,
Actually, Android Emulator uses mac80211_hwsim for wifi simulation
over virtio and it's working. This patch fixed the crash when we set
channels=2 to speed up scanning. I am trying to see if it makes sense
to upstream this patch since it's not Android-specific. Thanks!

Oh sure, I'll take a look and will probably apply it for the next cycle,
haven't done an in-depth review. I was just surprised somebody actually
*used* the virtio thing :-)

Does that mean virt_wifi isn't used anymore by the Android emulator?
Maybe then we should remove that again, it had some obscure bugs that
syzkaller found? Not that I mind it being around much, but ...

johannes

On Thu, May 6, 2021 at 2:13 PM Johannes Berg [off-list ref] wrote:

On Thu, 2021-05-06 at 14:11 -0700, Weilun Du wrote:

quoted

On Thu, May 6, 2021 at 11:19 AM Johannes Berg [off-list ref] wrote:

quoted

On Thu, 2021-05-06 at 11:05 -0700, Weilun Du wrote:

quoted

This fixed the crash when setting channels to 2 or more when
communicating over virtio.

Interesting, I thought I was probably the only user of virtio? :)

johannes

Hi Johannes,
Actually, Android Emulator uses mac80211_hwsim for wifi simulation
over virtio and it's working. This patch fixed the crash when we set
channels=2 to speed up scanning. I am trying to see if it makes sense
to upstream this patch since it's not Android-specific. Thanks!

Oh sure, I'll take a look and will probably apply it for the next cycle,
haven't done an in-depth review. I was just surprised somebody actually
*used* the virtio thing :-)

Does that mean virt_wifi isn't used anymore by the Android emulator?
Maybe then we should remove that again, it had some obscure bugs that
syzkaller found? Not that I mind it being around much, but ...

johannes

Thanks for looking into it. Actually, virt_wifi is still in use. There
are two different emulators that target different use cases. Android
emulator (goldfish) is mainly for third-party app developers. But yes
eventually, we are going to converge the Wi-Fi solution.