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| author | Magnus Karlsson <magnus.karlsson@intel.com> | 2018-06-29 09:48:17 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2018-07-02 18:37:11 -0700 |
| commit | 20b52a75166086a40d838397ef3db28a4f2c5998 (patch) | |
| tree | 5c6f0af2b630f695698e9c08459bad13d8abff26 /net/xdp | |
| parent | d0fbad0aec1df29717fab736eb24c8a49cf2c70b (diff) | |
| download | lwn-20b52a75166086a40d838397ef3db28a4f2c5998.tar.gz lwn-20b52a75166086a40d838397ef3db28a4f2c5998.zip | |
xsk: fix potential lost completion message in SKB path
The code in xskq_produce_addr erroneously checked if there
was up to LAZY_UPDATE_THRESHOLD amount of space in the completion
queue. It only needs to check if there is one slot left in the
queue. This bug could under some circumstances lead to a WARN_ON_ONCE
being triggered and the completion message to user space being lost.
Fixes: 35fcde7f8deb ("xsk: support for Tx")
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Reported-by: Pavel Odintsov <pavel@fastnetmon.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'net/xdp')
| -rw-r--r-- | net/xdp/xsk_queue.h | 9 |
1 files changed, 2 insertions, 7 deletions
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h index ef6a6f0ec949..52ecaf770642 100644 --- a/net/xdp/xsk_queue.h +++ b/net/xdp/xsk_queue.h @@ -62,14 +62,9 @@ static inline u32 xskq_nb_avail(struct xsk_queue *q, u32 dcnt) return (entries > dcnt) ? dcnt : entries; } -static inline u32 xskq_nb_free_lazy(struct xsk_queue *q, u32 producer) -{ - return q->nentries - (producer - q->cons_tail); -} - static inline u32 xskq_nb_free(struct xsk_queue *q, u32 producer, u32 dcnt) { - u32 free_entries = xskq_nb_free_lazy(q, producer); + u32 free_entries = q->nentries - (producer - q->cons_tail); if (free_entries >= dcnt) return free_entries; @@ -129,7 +124,7 @@ static inline int xskq_produce_addr(struct xsk_queue *q, u64 addr) { struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring; - if (xskq_nb_free(q, q->prod_tail, LAZY_UPDATE_THRESHOLD) == 0) + if (xskq_nb_free(q, q->prod_tail, 1) == 0) return -ENOSPC; ring->desc[q->prod_tail++ & q->ring_mask] = addr; |