diff options
Diffstat (limited to 'net/sunrpc/xprtrdma/xprt_rdma.h')
| -rw-r--r-- | net/sunrpc/xprtrdma/xprt_rdma.h | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h index 7723e5f..0028748 100644 --- a/net/sunrpc/xprtrdma/xprt_rdma.h +++ b/net/sunrpc/xprtrdma/xprt_rdma.h @@ -144,6 +144,26 @@ rdmab_to_msg(struct rpcrdma_regbuf *rb) #define RPCRDMA_DEF_GFP (GFP_NOIO | __GFP_NOWARN) +/* To ensure a transport can always make forward progress, + * the number of RDMA segments allowed in header chunk lists + * is capped at 8. This prevents less-capable devices and + * memory registrations from overrunning the Send buffer + * while building chunk lists. + * + * Elements of the Read list take up more room than the + * Write list or Reply chunk. 8 read segments means the Read + * list (or Write list or Reply chunk) cannot consume more + * than + * + * ((8 + 2) * read segment size) + 1 XDR words, or 244 bytes. + * + * And the fixed part of the header is another 24 bytes. + * + * The smallest inline threshold is 1024 bytes, ensuring that + * at least 750 bytes are available for RPC messages. + */ +#define RPCRDMA_MAX_HDR_SEGS (8) + /* * struct rpcrdma_rep -- this structure encapsulates state required to recv * and complete a reply, asychronously. It needs several pieces of @@ -456,7 +476,6 @@ struct rpcrdma_regbuf *rpcrdma_alloc_regbuf(struct rpcrdma_ia *, void rpcrdma_free_regbuf(struct rpcrdma_ia *, struct rpcrdma_regbuf *); -unsigned int rpcrdma_max_segments(struct rpcrdma_xprt *); int rpcrdma_ep_post_extra_recv(struct rpcrdma_xprt *, unsigned int); int frwr_alloc_recovery_wq(void); |
