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sfc: clear napi_hash state when copying channels

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commit 46d054f8f540612f09987a53154aa39ae15f2e4c upstream.

efx_copy_channel() doesn't correctly clear the napi_hash related state.
This means that when napi_hash_add is called for that channel nothing is
done, and we are left with a copy of the napi_hash_node from the old
channel. When we later call napi_hash_del() on this channel we have a
stale napi_hash_node.

Corruption is only seen when there are multiple entries in one of the
napi_hash lists. This is made more likely by having a very large number
of channels. Testing was carried out with 512 channels - 32 channels on
each of 16 ports.

This failure typically appears as protection faults within napi_by_id()
or napi_hash_add(). efx_copy_channel() is only used when tx or rx ring
sizes are changed (ethtool -G).

Fixes: 36763266bbe8 ("sfc: Add support for busy polling")
Signed-off-by: Bert Kenward <bkenward@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Bert Kenward 2016-11-11 15:56:51 +00:00 committed by Greg Kroah-Hartman
parent 46c7e03b46
commit 80cb976cb2
1 changed files with 3 additions and 0 deletions
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3
drivers/net/ethernet/sfc/efx.c
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@ -479,6 +479,9 @@ efx_copy_channel(const struct efx_channel *old_channel)
*channel = *old_channel;
channel->napi_dev = NULL;
INIT_HLIST_NODE(&channel->napi_str.napi_hash_node);
channel->napi_str.napi_id = 0;
channel->napi_str.state = 0;
memset(&channel->eventq, 0, sizeof(channel->eventq));
for (j = 0; j < EFX_TXQ_TYPES; j++) {