e1000: Delay flush queue when receive RCTL

e1000: Delay flush queue when receive RCTL

Due to too early RCT0 interrput, win10x32 may hang on booting.
This problem can be reproduced by doing power cycle on win10x32 guest.
In our environment, we have 10 win10x32 and stress power cycle.
The problem will happen about 20 rounds.

Below shows some log with comment:

The normal case:

22831@1551928392.984687:e1000x_rx_disabled Received packet dropped
because receive is disabled RCTL = 0
22831@1551928392.985655:e1000x_rx_disabled Received packet dropped
because receive is disabled RCTL = 0
22831@1551928392.985801:e1000x_rx_disabled Received packet dropped
because receive is disabled RCTL = 0
e1000: set_ics 0, ICR 0, IMR 0
e1000: set_ics 0, ICR 0, IMR 0
e1000: set_ics 0, ICR 0, IMR 0
e1000: RCTL: 0, mac_reg[RCTL] = 0x0
22831@1551928393.056710:e1000x_rx_disabled Received packet dropped
because receive is disabled RCTL = 0
e1000: set_ics 0, ICR 0, IMR 0
e1000: ICR read: 0
e1000: set_ics 0, ICR 0, IMR 0
e1000: set_ics 0, ICR 0, IMR 0
e1000: RCTL: 0, mac_reg[RCTL] = 0x0
22831@1551928393.077548:e1000x_rx_disabled Received packet dropped
because receive is disabled RCTL = 0
e1000: set_ics 0, ICR 0, IMR 0
e1000: ICR read: 0
e1000: set_ics 2, ICR 0, IMR 0
e1000: set_ics 2, ICR 2, IMR 0
e1000: RCTL: 0, mac_reg[RCTL] = 0x0
22831@1551928393.102974:e1000x_rx_disabled Received packet dropped
because receive is disabled RCTL = 0
22831@1551928393.103267:e1000x_rx_disabled Received packet dropped
because receive is disabled RCTL = 0
e1000: RCTL: 255, mac_reg[RCTL] = 0x40002 <- win10x32 says it can handle
RX now
e1000: set_ics 0, ICR 2, IMR 9d <- unmask interrupt
e1000: RCTL: 255, mac_reg[RCTL] = 0x48002
e1000: set_ics 80, ICR 2, IMR 9d <- interrupt and work!
...

The bad case:

27744@1551930483.117766:e1000x_rx_disabled Received packet dropped
because receive is disabled RCTL = 0
27744@1551930483.118398:e1000x_rx_disabled Received packet dropped
because receive is disabled RCTL = 0
e1000: set_ics 0, ICR 0, IMR 0
e1000: set_ics 0, ICR 0, IMR 0
e1000: set_ics 0, ICR 0, IMR 0
e1000: RCTL: 0, mac_reg[RCTL] = 0x0
27744@1551930483.198063:e1000x_rx_disabled Received packet dropped
because receive is disabled RCTL = 0
e1000: set_ics 0, ICR 0, IMR 0
e1000: ICR read: 0
e1000: set_ics 0, ICR 0, IMR 0
e1000: set_ics 0, ICR 0, IMR 0
e1000: RCTL: 0, mac_reg[RCTL] = 0x0
27744@1551930483.218675:e1000x_rx_disabled Received packet dropped
because receive is disabled RCTL = 0
e1000: set_ics 0, ICR 0, IMR 0
e1000: ICR read: 0
e1000: set_ics 2, ICR 0, IMR 0
e1000: set_ics 2, ICR 2, IMR 0
e1000: RCTL: 0, mac_reg[RCTL] = 0x0
27744@1551930483.241768:e1000x_rx_disabled Received packet dropped
because receive is disabled RCTL = 0
27744@1551930483.241979:e1000x_rx_disabled Received packet dropped
because receive is disabled RCTL = 0
e1000: RCTL: 255, mac_reg[RCTL] = 0x40002 <- win10x32 says it can handle
RX now
e1000: set_ics 80, ICR 2, IMR 0 <- flush queue (caused by setting RCTL)
e1000: set_ics 0, ICR 82, IMR 9d <- unmask interrupt and because 0x82&0x9d
!= 0 generate interrupt, hang on here...

To workaround this problem, simply delay flush queue. Also stop receiving
when timer is going to run.

Tested on CentOS, Win7SP1x64 and Win10x32.

Signed-off-by: yuchenlin <yuchenlin@synology.com>
Reviewed-by: Dmitry Fleytman <dmitry.fleytman@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>