Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail.tpi.com ([70.99.223.143]:2901 "EHLO mail.tpi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754767Ab3CKVPV (ORCPT ); Mon, 11 Mar 2013 17:15:21 -0400 From: Tim Gardner To: linux-kernel@vger.kernel.org Cc: Tim Gardner , Trond Myklebust , "J. Bruce Fields" , "David S. Miller" , Tom Tucker , Haggai Eran , Or Gerlitz , Shani Michaeli , linux-nfs@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH linux-next v3] SUNRPC: rpcrdma_register_default_external: Dynamically allocate ib_phys_buf Date: Mon, 11 Mar 2013 15:15:08 -0600 Message-Id: <1363036508-24935-1-git-send-email-tim.gardner@canonical.com> In-Reply-To: <4FA345DA4F4AE44899BD2B03EEEC2FA9286BA156@sacexcmbx05-prd.hq.netapp.com> References: <4FA345DA4F4AE44899BD2B03EEEC2FA9286BA156@sacexcmbx05-prd.hq.netapp.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: rpcrdma_register_default_external() is several frames into the call stack which goes deeper yet. You run the risk of stack corruption by declaring such a large automatic variable, so move the array of 'struct ib_phys_buf' objects into the transport structure 'struct rpcrdma_xprt' (which is dynamically allocated) in order to silence the frame-larger-than warning. Access to each struct rpcrdma_xprt is serialized by XPRT_LOCKED in xprt_reserve_xprt(), so there is no danger of multiple accessors to the array of struct ib_phys_buf objects. net/sunrpc/xprtrdma/verbs.c: In function 'rpcrdma_register_default_external': net/sunrpc/xprtrdma/verbs.c:1774:1: warning: the frame size of 1056 bytes is larger than 1024 bytes [-Wframe-larger-than=] gcc version 4.6.3 Cc: Trond Myklebust Cc: "J. Bruce Fields" Cc: "David S. Miller" Cc: Tom Tucker Cc: Haggai Eran Cc: Or Gerlitz Cc: Shani Michaeli Cc: linux-nfs@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Tim Gardner --- v1 - Use kmalloc() to dynamically allocate and free the array of 'struct ib_phys_buf' objects v2 - Move the array of 'struct ib_phys_buf' objects into struct rpcrdma_req and pass this request down through rpcrdma_register_external() and rpcrdma_register_default_external(). This is less overhead then using kmalloc() and requires no extra error checking as the allocation burden is shifted to the transport client. v3 - Move the array of 'struct ib_phys_buf' objects into struct rpcrdma_xprt. Pass a pointer to this transport structure into rpcrdma_register_default_external(). This is less overhead then using kmalloc() and requires no extra error checking as the allocation burden is shifted to the transport client. net/sunrpc/xprtrdma/verbs.c | 10 ++++++---- net/sunrpc/xprtrdma/xprt_rdma.h | 5 ++++- 2 files changed, 10 insertions(+), 5 deletions(-) diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c index 93726560..c7aa3da 100644 --- a/net/sunrpc/xprtrdma/verbs.c +++ b/net/sunrpc/xprtrdma/verbs.c @@ -1730,13 +1730,14 @@ rpcrdma_deregister_memwin_external(struct rpcrdma_mr_seg *seg, } static int -rpcrdma_register_default_external(struct rpcrdma_mr_seg *seg, - int *nsegs, int writing, struct rpcrdma_ia *ia) +rpcrdma_register_default_external(struct rpcrdma_xprt *r_xprt, + struct rpcrdma_mr_seg *seg, int *nsegs, int writing, + struct rpcrdma_ia *ia) { int mem_priv = (writing ? IB_ACCESS_REMOTE_WRITE : IB_ACCESS_REMOTE_READ); struct rpcrdma_mr_seg *seg1 = seg; - struct ib_phys_buf ipb[RPCRDMA_MAX_DATA_SEGS]; + struct ib_phys_buf *ipb = r_xprt->ipb; int len, i, rc = 0; if (*nsegs > RPCRDMA_MAX_DATA_SEGS) @@ -1827,7 +1828,8 @@ rpcrdma_register_external(struct rpcrdma_mr_seg *seg, /* Default registration each time */ default: - rc = rpcrdma_register_default_external(seg, &nsegs, writing, ia); + rc = rpcrdma_register_default_external(r_xprt, seg, &nsegs, + writing, ia); break; } if (rc) diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h index cc1445d..d7b440f 100644 --- a/net/sunrpc/xprtrdma/xprt_rdma.h +++ b/net/sunrpc/xprtrdma/xprt_rdma.h @@ -269,7 +269,8 @@ struct rpcrdma_stats { * for convenience. This structure need not be visible externally. * * It is allocated and initialized during mount, and released - * during unmount. + * during unmount. Access to this structure is serialized by XPRT_LOCKED + * in xprt_reserve_xprt(). */ struct rpcrdma_xprt { struct rpc_xprt xprt; @@ -279,6 +280,8 @@ struct rpcrdma_xprt { struct rpcrdma_create_data_internal rx_data; struct delayed_work rdma_connect; struct rpcrdma_stats rx_stats; + /* temp work array */ + struct ib_phys_buf ipb[RPCRDMA_MAX_DATA_SEGS]; }; #define rpcx_to_rdmax(x) container_of(x, struct rpcrdma_xprt, xprt) -- 1.7.9.5