Re: [PATCH] ethtool: don't overwrite useful bits in advertising bitfield
From: Ben Hutchings <hidden>
Date: 2012-08-20 15:23:03
On Tue, 2012-08-14 at 16:15 +0200, Johan Gunnarsson wrote:
There are bits in this bitfield that we want to leave untouched (PAUSE and ASYM_PAUSE bits) when changing other bits (speed and duplex bits.) Previously, these were always overwritten to zero when running commands like "ethtool -s eth0 speed 10 duplex full autoneg off".
This is right in principle, but the implementation isn't quite right.
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Signed-off-by: Johan Gunnarsson <redacted> --- ethtool.c | 45 +++++++++++++++++++++++++++++++-------------- 1 file changed, 31 insertions(+), 14 deletions(-)diff --git a/ethtool.c b/ethtool.c index e573357..efa12c7 100644 --- a/ethtool.c +++ b/ethtool.c@@ -46,6 +46,18 @@ #define MAX_ADDR_LEN 32 #endif +#define ALL_ADVERTISED_MODES \ + (ADVERTISED_10baseT_Half | \ + ADVERTISED_10baseT_Full | \ + ADVERTISED_100baseT_Half | \ + ADVERTISED_100baseT_Full | \ + ADVERTISED_1000baseT_Half | \ + ADVERTISED_1000baseT_Full | \ + ADVERTISED_2500baseX_Full | \ + ADVERTISED_10000baseT_Full | \ + ADVERTISED_20000baseMLD2_Full | \ + ADVERTISED_20000baseKR2_Full)
This is missing the new 40G modes (not a regression, I realise). [...]
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@@ -2405,19 +2421,20 @@ static int do_sset(struct cmd_context *ctx) } if (autoneg_wanted == AUTONEG_ENABLE && advertising_wanted == 0) { - ecmd.advertising = ecmd.supported & - (ADVERTISED_10baseT_Half | - ADVERTISED_10baseT_Full | - ADVERTISED_100baseT_Half | - ADVERTISED_100baseT_Full | - ADVERTISED_1000baseT_Half | - ADVERTISED_1000baseT_Full | - ADVERTISED_2500baseX_Full | - ADVERTISED_10000baseT_Full | - ADVERTISED_20000baseMLD2_Full | - ADVERTISED_20000baseKR2_Full); + /* Auto negotation enabled, but with + * unspecified speed and duplex: enable all + * supported speeds and duplexes. + */ + ecmd.advertising = (ecmd.advertising & + ~ALL_ADVERTISED_MODES) | + (ALL_ADVERTISED_MODES & ecmd.supported);
Perhaps we should also warn if there's a 'supported' flag we don't recognise, because we don't know whether it's a link mode and we might be failing to enable/disable it as requested.
} else if (advertising_wanted > 0) {
- ecmd.advertising = advertising_wanted;
+ /* Enable all requested modes */
+ ecmd.advertising = (ecmd.advertising &
+ ~ALL_ADVERTISED_MODES) |
+ (advertising_wanted & ecmd.supported);I don't think the '& ecmd.supported' here is right. If an autoneg device supports some new link mode L that is not in ALL_ADVERTISED_MODES, but not link mode M which the user requested, then this can silently fail because the resulting advertising mask will include L but not M. We should either use advertising_wanted unmasked and let the driver validate it, or report an error if it's not present in the supported mask. I think we should be consistent with the following case, i.e. let the driver validate it. Ben.
+ } else if (full_advertising_wanted > 0) {
+ ecmd.advertising = full_advertising_wanted;
}
/* Try to perform the update. */-- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.