This is the result of 2773395b34883fe54418de188733a63bb38e0ad6. Steve might want to weigh in on this since it was done for performance reasons.

Tom

On 3/10/13 10:39 AM, 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 dynamically allocate the array of 'struct ib_phys_buf' objects in
order to silence the frame-larger-than warning.

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 <[email protected]>
Cc: "J. Bruce Fields" <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Tom Tucker <[email protected]>
Cc: Haggai Eran <[email protected]>
Cc: Or Gerlitz <[email protected]>
Cc: Shani Michaeli <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Tim Gardner <[email protected]>
---
  net/sunrpc/xprtrdma/verbs.c |    7 ++++++-
  1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 93726560..0916467 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -1736,9 +1736,13 @@ rpcrdma_register_default_external(struct rpcrdma_mr_seg 
*seg,
        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;
        int len, i, rc = 0;
+ ipb = kmalloc(sizeof(*ipb) * RPCRDMA_MAX_DATA_SEGS, GFP_KERNEL);
+       if (!ipb)
+               return -ENOMEM;
+
        if (*nsegs > RPCRDMA_MAX_DATA_SEGS)
                *nsegs = RPCRDMA_MAX_DATA_SEGS;
        for (len = 0, i = 0; i < *nsegs;) {
@@ -1770,6 +1774,7 @@ rpcrdma_register_default_external(struct rpcrdma_mr_seg 
*seg,
                seg1->mr_len = len;
        }
        *nsegs = i;
+       kfree(ipb);
        return rc;
  }

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