thorpej 7a9a30c5e7 Define and implement a locking protocol for the ifmedia / mii layers:
- MP-safe drivers provide a mutex to ifmedia that is used to serialize
  access to media-related structures / hardware regsiters.  Converted
  drivers use the new ifmedia_init_with_lock() function for this.  The
  new name is provided to ease the transition.
- Un-converted drivers continue to call ifmedia_init(), which will supply
  a compatibility lock to be used instead.  Several media-related entry
  points must be aware of this compatibility lock, and are able to acquire
  it recursively a limited number of times, if needed.  This is a SPIN
  mutex with priority IPL_NET.
- This same lock is used to serialize access to PHY registers and other
  MII-related data structures.

The PHY drivers are modified to acquire and release the lock, as needed,
and assert the lock is held as a diagnostic aid.

The "usbnet" framework has had an overhaul of its internal locking
protocols to fit in with the media / mii changes, and the drivers adapted.

USB wifi drivers have been changed to provide their own adaptive mutex
to the ifmedia later via a new ieee80211_media_init_with_lock() function.
This is required because the USB drivers need an adaptive mutex.

Besised "usbnet", a few other drivers are converted: vmx, wm, ixgbe / ixv.

mcx also now calls ifmedia_init_with_lock() because it needs to also use
an adaptive mutex.  The mcx driver still needs to be fully converted to
NET_MPSAFE.
2020-03-15 23:04:50 +00:00
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