Remove ethernet interface logic for SoftAP and STA #12842
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Issue: The problem is that there is a race condition introduced in that the LWIP thread is relying on the interface as it is taken down by a application thread while calling disconnect. In disconnect api called from application context, whd_emac_wifi_link_state_changed() will refer to netif interface structure in its callback api netif_link_irq(netif). This netif will be cleared by remove_etherent_interface(). whd_emac_wifi_link_state_changed will post message to tcpip_thread. tcpip_thread will process the message and call the callback api netif_link_irq(netif) Calling sequence is whd_emac_wifi_link_state_changed -> remove_etherent_interface(). Hence there is a timing issue that netif might be cleared first before tcpip thread process the message netif_link_irq(netif) Fix: remove_etherent_interface() will post message to tcpip thread and tcpip: thread process the message delete_interface() which will actually remove the inferface from the netif_list. Calling sequence is whd_emac_wifi_link_state_changed() message post -> remove_etherent_interface() message post. message processing order netif_link_irq(netif) -> delete_interface(). Since both the processing is handled in single thread, processing of message is handled sequentially.
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@cy-arsm, thank you for your changes. |
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@cy-arsm Please provide further information: is this already on master? Why is this requesting to be on 5.15 ? |
0xc0170
approved these changes
Apr 22, 2020
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CI started |
Test run: SUCCESSSummary: 10 of 10 test jobs passed |
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Modified LwIP mbed-os wrapper LWIPInterface.cpp to add an api remove interface which will be called as part of WhdSoftAPInterface::stop() to support sending UDP IPv6 packet is sent over link-local interface
Issue: udp_sendto() Fails for multicast IPV6 packet when interface is switched from SoftAP to STA mode.
When SoftAP start is called, add_ethernet_interface() will be called internally to add interface details into netif_list.
When switching from SoftAP to STA mode, add_ethernet_interface() will be called again to append the interace details into netif_list.
When udp_sendto() is called, ip6_route() will return interface as NULL since it consider device as single interface.
Summary of changes
LWIPInterface.cpp
LWIP::remove_ethernet_interface() api is added to remove the interface from the netif_list.
WhdSoftAPInterface.cpp
WhdSoftAPInterface::stop(), calling remove_ethernet_interface() from the network list which was added as part of WhdSoftAPInterface::start()
WhdSTAInterface.cpp
WhdSTAInterface::stop(), calling remove_ethernet_interface() from the network list which was added as part of WhdSTAInterface::start()
Impact of changes
Migration actions required
Documentation
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