• Jakub Kicinski's avatar
    net: disable netpoll on fresh napis · 96e97bc0
    Jakub Kicinski authored
    napi_disable() makes sure to set the NAPI_STATE_NPSVC bit to prevent
    netpoll from accessing rings before init is complete. However, the
    same is not done for fresh napi instances in netif_napi_add(),
    even though we expect NAPI instances to be added as disabled.
    
    This causes crashes during driver reconfiguration (enabling XDP,
    changing the channel count) - if there is any printk() after
    netif_napi_add() but before napi_enable().
    
    To ensure memory ordering is correct we need to use RCU accessors.
    Reported-by: default avatarRob Sherwood <rsher@fb.com>
    Fixes: 2d8bff12 ("netpoll: Close race condition between poll_one_napi and napi_disable")
    Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    96e97bc0
dev.c 274 KB