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Date: Wed, 29 Apr 2009 23:58:18 +0200 From: Lennert Buytenhek <buytenh@...tstofly.org> To: davem@...emloft.net, netdev@...r.kernel.org Subject: [PATCH 2/2] mv643xx_eth: 64bit mib counter read fix On several mv643xx_eth hardware versions, the two 64bit mib counters for 'good octets received' and 'good octets sent' are actually 32bit counters, and reading from the upper half of the register has the same effect as reading from the lower half of the register: an atomic read-and-clear of the entire 32bit counter value. This can under heavy traffic occasionally lead to small numbers being added to the upper half of the 64bit mib counter even though no 32bit wrap has occured. Since we poll the mib counters at least every 30 seconds anyway, we might as well just skip the reads of the upper halves of the hardware counters without breaking the stats, which this patch does. Signed-off-by: Lennert Buytenhek <buytenh@...vell.com> Cc: stable@...nel.org --- drivers/net/mv643xx_eth.c | 2 -- 1 files changed, 0 insertions(+), 2 deletions(-) diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c index 038beff..a400d71 100644 --- a/drivers/net/mv643xx_eth.c +++ b/drivers/net/mv643xx_eth.c @@ -1255,7 +1255,6 @@ static void mib_counters_update(struct mv643xx_eth_private *mp) spin_lock_bh(&mp->mib_counters_lock); p->good_octets_received += mib_read(mp, 0x00); - p->good_octets_received += (u64)mib_read(mp, 0x04) << 32; p->bad_octets_received += mib_read(mp, 0x08); p->internal_mac_transmit_err += mib_read(mp, 0x0c); p->good_frames_received += mib_read(mp, 0x10); @@ -1269,7 +1268,6 @@ static void mib_counters_update(struct mv643xx_eth_private *mp) p->frames_512_to_1023_octets += mib_read(mp, 0x30); p->frames_1024_to_max_octets += mib_read(mp, 0x34); p->good_octets_sent += mib_read(mp, 0x38); - p->good_octets_sent += (u64)mib_read(mp, 0x3c) << 32; p->good_frames_sent += mib_read(mp, 0x40); p->excessive_collision += mib_read(mp, 0x44); p->multicast_frames_sent += mib_read(mp, 0x48); -- 1.5.6.4 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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