On 3/11/13 4:25 PM, J. Bruce Fields wrote:
On Mon, Mar 11, 2013 at 03:15:08PM -0600, Tim Gardner wrote: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 <Trond.Myklebust@xxxxxxxxxx> Cc: "J. Bruce Fields" <bfields@xxxxxxxxxxxx> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx> Cc: Tom Tucker <tom@xxxxxx> Cc: Haggai Eran <haggaie@xxxxxxxxxxxx> Cc: Or Gerlitz <ogerlitz@xxxxxxxxxxxx> Cc: Shani Michaeli <shanim@xxxxxxxxxxxx> Cc: linux-nfs@xxxxxxxxxxxxxxx Cc: netdev@xxxxxxxxxxxxxxx Signed-off-by: Tim Gardner <tim.gardner@xxxxxxxxxxxxx> --- 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.Looks good to me; wish we could get it tested....
I will test it. Tim could you please send me a final version that you'd like tested as a single message?
Would someone (like Tim maybe ... hint hint) look at tearing out all those dead registration strategies? I don't think we need or will ever use bounce-buffers, memory windows, or mlnx fmr. The only two that are used and tested are all-phys and FRMR (the default).
Tom
In future if we do decide to also increase the size of that array we may need to allocate it separately from struct rpcrdma_xprt itself, which looks already fairly large without it; on x86_64: $ gdb net/sunrpc/xprtrdma/xprtrdma.ko ... (gdb) p sizeof(struct rpcrdma_xprt) $1 = 2912 But that shouldn't be a big deal to do. --b.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
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