Messages in this thread | | | Date | Mon, 11 Mar 2013 18:02:09 -0500 | From | Tom Tucker <> | Subject | Re: [PATCH linux-next v3] SUNRPC: rpcrdma_register_default_external: Dynamically allocate ib_phys_buf |
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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@netapp.com> >> Cc: "J. Bruce Fields" <bfields@fieldses.org> >> Cc: "David S. Miller" <davem@davemloft.net> >> Cc: Tom Tucker <tom@ogc.us> >> Cc: Haggai Eran <haggaie@mellanox.com> >> Cc: Or Gerlitz <ogerlitz@mellanox.com> >> Cc: Shani Michaeli <shanim@mellanox.com> >> Cc: linux-nfs@vger.kernel.org >> Cc: netdev@vger.kernel.org >> Signed-off-by: Tim Gardner <tim.gardner@canonical.com> >> --- >> 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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