kern/53902: Some drivers do infinite loop in mii_{read,write}reg().

[msaitoh%execsw.org@localhost]

>Number:         53902
>Category:       kern
>Synopsis:       Some drivers do infinite loop in mii_{read,write}reg().
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    kern-bug-people
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Wed Jan 23 03:25:00 +0000 2019
>Originator:     msaitoh%execsw.org@localhost
>Release:        all
>Organization:
>Description:
	I noticed that the following code do infinite loop in the MII register
	read/wirte function. If it accesses an unimplemented PHY register,
	it will hang. It should be fixed:

		arm/at91/at91emac.c
		arm/ep93xx/epe.c
		arm/omap/omapl1x_emac.c
		mips/ralink/ralink_eth.c
		arch/powerpc/booke/dev/pq3etsec.c(read)
		dev/cadence/if_cemac.c
		dev/ic/lan9118.c

>How-To-Repeat:
	Attach a PHY driver which accesses an unimplemented PHY register.
>Fix:
	Add timeout.

>Unformatted:
 System: *
 Architecture: *
 Machine: *