ethtool: fec: add note about reuse of reserved

struct ethtool_fecparam::reserved can't be used in SET, because
ethtool user space doesn't zero-initialize the structure.
Make this clear.

Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jakub Kicinski 2021-03-26 13:22:21 -07:00 committed by David S. Miller
parent f59798b8f6
commit ad1cd7856d
1 changed files with 4 additions and 0 deletions

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@ -1382,6 +1382,10 @@ struct ethtool_per_queue_op {
* @fec: Bitmask of configured FEC modes.
* @reserved: Reserved for future extensions, ignore on GET, write 0 for SET.
*
* Note that @reserved was never validated on input and ethtool user space
* left it uninitialized when calling SET. Hence going forward it can only be
* used to return a value to userspace with GET.
*
* FEC modes supported by the device can be read via %ETHTOOL_GLINKSETTINGS.
* FEC settings are configured by link autonegotiation whenever it's enabled.
* With autoneg on %ETHTOOL_GFECPARAM can be used to read the current mode.