diff options
| author | Jakub Kicinski <jakub.kicinski@netronome.com> | 2018-07-21 07:14:39 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-07-22 20:58:52 +0300 |
| commit | 07300f774fec9519663a597987a4083225588be4 (patch) | |
| tree | cd633e5d64cb7df898460e95a760a1205f76be5a | |
| parent | 042f8825569d628517784d558aefe23c212f0fb2 (diff) | |
| download | linux-07300f774fec9519663a597987a4083225588be4.tar.xz | |
nfp: avoid buffer leak when FW communication fails
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>
| -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 279b8ab8a17b..cf1704e972b7 100644 --- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c +++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c @@ -1078,7 +1078,7 @@ static bool nfp_net_xdp_complete(struct nfp_net_tx_ring *tx_ring) * @dp: NFP Net data path struct * @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_dp *dp, struct nfp_net_tx_ring *tx_ring) @@ -1280,13 +1280,18 @@ static void nfp_net_rx_give_one(const struct nfp_net_dp *dp, * 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 = D_IDX(rx_ring, rx_ring->wr_p); last_idx = rx_ring->cnt - 1; @@ -2508,6 +2513,8 @@ 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) { |