Split out the code that manages the rb_mws list. A little extra error checking is introduced in the code path that grabs MWs for the next RPC request. If rb_mws were ever to become empty, the list_entry() would cause a NULL pointer dereference.
Instead, now rpcrdma_buffer_get() returns NULL, which causes call_allocate() to delay and try again. Signed-off-by: Chuck Lever <[email protected]> --- net/sunrpc/xprtrdma/verbs.c | 105 +++++++++++++++++++++++++++------------ net/sunrpc/xprtrdma/xprt_rdma.h | 1 2 files changed, 74 insertions(+), 32 deletions(-) diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c index 3efc007..f24f0bf 100644 --- a/net/sunrpc/xprtrdma/verbs.c +++ b/net/sunrpc/xprtrdma/verbs.c @@ -1251,6 +1251,69 @@ rpcrdma_buffer_destroy(struct rpcrdma_buffer *buf) kfree(buf->rb_pool); } +static void +rpcrdma_put_mw_locked(struct rpcrdma_mw *mw) +{ + list_add_tail(&mw->mw_list, &mw->mw_pool->rb_mws); +} + +static void +rpcrdma_buffer_put_mw(struct rpcrdma_mw **mw) +{ + rpcrdma_put_mw_locked(*mw); + *mw = NULL; +} + +/* Cycle mw's back in reverse order, and "spin" them. + * This delays and scrambles reuse as much as possible. + */ +static void +rpcrdma_buffer_put_mws(struct rpcrdma_req *req) +{ + struct rpcrdma_mr_seg *seg1 = req->rl_segments; + struct rpcrdma_mr_seg *seg = seg1; + int i; + + for (i = 1, seg++; i < RPCRDMA_MAX_SEGS; seg++, i++) + rpcrdma_buffer_put_mw(&seg->mr_chunk.rl_mw); + rpcrdma_buffer_put_mw(&seg1->mr_chunk.rl_mw); +} + +static void +rpcrdma_send_buffer_put(struct rpcrdma_req *req, struct rpcrdma_buffer *buffers) +{ + buffers->rb_send_bufs[--buffers->rb_send_index] = req; + req->rl_niovs = 0; + if (req->rl_reply) { + buffers->rb_recv_bufs[--buffers->rb_recv_index] = req->rl_reply; + req->rl_reply->rr_func = NULL; + req->rl_reply = NULL; + } +} + +static struct rpcrdma_req * +rpcrdma_buffer_get_mws(struct rpcrdma_req *req, struct rpcrdma_buffer *buffers) +{ + struct rpcrdma_mw *r; + int i; + + for (i = RPCRDMA_MAX_SEGS - 1; i >= 0; i--) { + if (list_empty(&buffers->rb_mws)) + goto out_empty; + + r = list_entry(buffers->rb_mws.next, + struct rpcrdma_mw, mw_list); + list_del(&r->mw_list); + r->mw_pool = buffers; + req->rl_segments[i].mr_chunk.rl_mw = r; + } + return req; +out_empty: + rpcrdma_send_buffer_put(req, buffers); + rpcrdma_buffer_put_mws(req); + return NULL; +} + /* * Get a set of request/reply buffers. * @@ -1263,10 +1326,9 @@ rpcrdma_buffer_destroy(struct rpcrdma_buffer *buf) struct rpcrdma_req * rpcrdma_buffer_get(struct rpcrdma_buffer *buffers) { + struct rpcrdma_ia *ia = rdmab_to_ia(buffers); struct rpcrdma_req *req; unsigned long flags; - int i; - struct rpcrdma_mw *r; spin_lock_irqsave(&buffers->rb_lock, flags); if (buffers->rb_send_index == buffers->rb_max_requests) { @@ -1286,14 +1348,13 @@ rpcrdma_buffer_get(struct rpcrdma_buffer *buffers) buffers->rb_recv_bufs[buffers->rb_recv_index++] = NULL; } buffers->rb_send_bufs[buffers->rb_send_index++] = NULL; - if (!list_empty(&buffers->rb_mws)) { - i = RPCRDMA_MAX_SEGS - 1; - do { - r = list_entry(buffers->rb_mws.next, - struct rpcrdma_mw, mw_list); - list_del(&r->mw_list); - req->rl_segments[i].mr_chunk.rl_mw = r; - } while (--i >= 0); + switch (ia->ri_memreg_strategy) { + case RPCRDMA_FRMR: + case RPCRDMA_MTHCAFMR: + req = rpcrdma_buffer_get_mws(req, buffers); + break; + default: + break; } spin_unlock_irqrestore(&buffers->rb_lock, flags); return req; @@ -1308,34 +1369,14 @@ rpcrdma_buffer_put(struct rpcrdma_req *req) { struct rpcrdma_buffer *buffers = req->rl_buffer; struct rpcrdma_ia *ia = rdmab_to_ia(buffers); - int i; unsigned long flags; spin_lock_irqsave(&buffers->rb_lock, flags); - buffers->rb_send_bufs[--buffers->rb_send_index] = req; - req->rl_niovs = 0; - if (req->rl_reply) { - buffers->rb_recv_bufs[--buffers->rb_recv_index] = req->rl_reply; - req->rl_reply->rr_func = NULL; - req->rl_reply = NULL; - } + rpcrdma_send_buffer_put(req, buffers); switch (ia->ri_memreg_strategy) { case RPCRDMA_FRMR: case RPCRDMA_MTHCAFMR: - /* - * Cycle mw's back in reverse order, and "spin" them. - * This delays and scrambles reuse as much as possible. - */ - i = 1; - do { - struct rpcrdma_mw **mw; - mw = &req->rl_segments[i].mr_chunk.rl_mw; - list_add_tail(&(*mw)->mw_list, &buffers->rb_mws); - *mw = NULL; - } while (++i < RPCRDMA_MAX_SEGS); - list_add_tail(&req->rl_segments[0].mr_chunk.rl_mw->mw_list, - &buffers->rb_mws); - req->rl_segments[0].mr_chunk.rl_mw = NULL; + rpcrdma_buffer_put_mws(req); break; default: break; diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h index 6b5d243..b81e5b5 100644 --- a/net/sunrpc/xprtrdma/xprt_rdma.h +++ b/net/sunrpc/xprtrdma/xprt_rdma.h @@ -175,6 +175,7 @@ struct rpcrdma_mw { struct rpcrdma_frmr frmr; } r; struct list_head mw_list; + struct rpcrdma_buffer *mw_pool; }; #define RPCRDMA_BIT_FASTREG (0) -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
