Re: [PATCH] net: dsa: mv88e6xxx: fix handling of upper half of STATS_TYPE_PORT
From: Andrew Lunn <andrew@lunn.ch>
Date: 2019-05-28 13:45:05
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On Tue, May 28, 2019 at 01:17:10PM +0000, Rasmus Villemoes wrote:
Currently, the upper half of a 4-byte STATS_TYPE_PORT statistic ends up in bits 47:32 of the return value, instead of bits 31:16 as they should. Signed-off-by: Rasmus Villemoes <redacted>
Hi Rasmus
Please include a Fixes tag, to indicate where the problem was
introduced. In this case, i think it was:
Fixes: 6e46e2d821bb ("net: dsa: mv88e6xxx: Fix u64 statistics")
And set the Subject to [PATCH net] to indicate this should be applied
to the net tree.
quoted hunk ↗ jump to hunk
--- I also noticed that it's a bit inconsistent that we return U64_MAX if there's a read error in STATS_TYPE_PORT, while mv88e6xxx_g1_stats_read() returns 0 in case of a read error. In practice, register reads probably never fail so it doesn't matter. drivers/net/dsa/mv88e6xxx/chip.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c index 370434bdbdab..317553d2cb21 100644 --- a/drivers/net/dsa/mv88e6xxx/chip.c +++ b/drivers/net/dsa/mv88e6xxx/chip.c@@ -785,7 +785,7 @@ static uint64_t _mv88e6xxx_get_ethtool_stat(struct mv88e6xxx_chip *chip, err = mv88e6xxx_port_read(chip, port, s->reg + 1, ®); if (err) return U64_MAX; - high = reg; + low |= ((u32)reg) << 16; } break; case STATS_TYPE_BANK1:
What i don't like about this is how the function finishes:
}
value = (((u64)high) << 32) | low;
return value;
}
A better fix might be
- break
+ value = (((u64)high) << 16 | low;
+ return value;
Andrew