diff options
| author | Jakub Kicinski <jakub.kicinski@netronome.com> | 2018-07-20 21:14:39 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-09-26 08:36:33 +0200 |
| commit | 8e824a3c7ede194620bc23ba458f01b561e5bd00 (patch) | |
| tree | be4516452b75d54d63772ec527214dd4e127ea6e /drivers/net | |
| parent | be2338f3a57f004a9b33ac6c23ab062061d37b7d (diff) | |
nfp: avoid buffer leak when FW communication fails
[ Upstream commit 07300f774fec9519663a597987a4083225588be4 ]
After device is stopped we reset the rings by moving all free buffers
to positions [0, cnt - 2], and clear the position cnt - 1 in the ring.
We then proceed to clear the read/write pointers. This means that if
we try to reset the ring again the code will assume that the next to
fill buffer is at position 0 and swap it with cnt - 1. Since we
previously cleared position cnt - 1 it will lead to leaking the first
buffer and leaving ring in a bad state.
This scenario can only happen if FW communication fails, in which case
the ring will never be used again, so the fact it's in a bad state will
not be noticed. Buffer leak is the only problem. Don't try to move
buffers in the ring if the read/write pointers indicate the ring was
never used or have already been reset.
nfp_net_clear_config_and_disable() is now fully idempotent.
Found by code inspection, FW communication failures are very rare,
and reconfiguring a live device is not common either, so it's unlikely
anyone has ever noticed the leak.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/net')
| -rw-r--r-- | drivers/net/ethernet/netronome/nfp/nfp_net_common.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c index eee6e59e6cf3..2e8703da536d 100644 --- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c +++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c @@ -990,7 +990,7 @@ static void nfp_net_tx_complete(struct nfp_net_tx_ring *tx_ring) * @nn: NFP Net device * @tx_ring: TX ring structure * - * Assumes that the device is stopped + * Assumes that the device is stopped, must be idempotent. */ static void nfp_net_tx_ring_reset(struct nfp_net *nn, struct nfp_net_tx_ring *tx_ring) @@ -1144,13 +1144,18 @@ static void nfp_net_rx_give_one(struct nfp_net_rx_ring *rx_ring, * nfp_net_rx_ring_reset() - Reflect in SW state of freelist after disable * @rx_ring: RX ring structure * - * Warning: Do *not* call if ring buffers were never put on the FW freelist - * (i.e. device was not enabled)! + * Assumes that the device is stopped, must be idempotent. */ static void nfp_net_rx_ring_reset(struct nfp_net_rx_ring *rx_ring) { unsigned int wr_idx, last_idx; + /* wr_p == rd_p means ring was never fed FL bufs. RX rings are always + * kept at cnt - 1 FL bufs. + */ + if (rx_ring->wr_p == 0 && rx_ring->rd_p == 0) + return; + /* Move the empty entry to the end of the list */ wr_idx = rx_ring->wr_p % rx_ring->cnt; last_idx = rx_ring->cnt - 1; @@ -1919,6 +1924,8 @@ static void nfp_net_vec_clear_ring_data(struct nfp_net *nn, unsigned int idx) /** * nfp_net_clear_config_and_disable() - Clear control BAR and disable NFP * @nn: NFP Net device to reconfigure + * + * Warning: must be fully idempotent. */ static void nfp_net_clear_config_and_disable(struct nfp_net *nn) { |