2012-10-27 03:06:42

by Jim Rees

Subject: [PATCH] NFS: Reduce stack use in encode_exchange_id()

For comment only. I have not tested this.

encode_exchange_id() uses more stack space than necessary, giving a compile
time warning. Reduce the size of the static buffer for implementation name.

Signed-off-by: Jim Rees <[email protected]>
---
fs/nfs/nfs4xdr.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 8dba6bd..ccd1dde 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -1700,12 +1700,15 @@ static void encode_bind_conn_to_session(struct xdr_stream *xdr,
*p = 0; /* use_conn_in_rdma_mode = False */
}

+#define IMPL_NAME_LIMIT (sizeof(utsname()->sysname) + sizeof(utsname()->release) + \
+ sizeof(utsname()->version) + sizeof(utsname()->machine) + 8)
+
static void encode_exchange_id(struct xdr_stream *xdr,
struct nfs41_exchange_id_args *args,
struct compound_hdr *hdr)
{
__be32 *p;
- char impl_name[NFS4_OPAQUE_LIMIT];
+ char impl_name[IMPL_NAME_LIMIT];
int len = 0;

encode_op_hdr(xdr, OP_EXCHANGE_ID, decode_exchange_id_maxsz, hdr);
@@ -1720,7 +1723,7 @@ static void encode_exchange_id(struct xdr_stream *xdr,
if (send_implementation_id &&
sizeof(CONFIG_NFS_V4_1_IMPLEMENTATION_ID_DOMAIN) > 1 &&
sizeof(CONFIG_NFS_V4_1_IMPLEMENTATION_ID_DOMAIN)
- <= NFS4_OPAQUE_LIMIT + 1)
+ <= sizeof(impl_name) + 1)
len = snprintf(impl_name, sizeof(impl_name), "%s %s %s %s",
utsname()->sysname, utsname()->release,
utsname()->version, utsname()->machine);
--
1.7.9.5

2012-10-27 14:03:55

by Adamson, Dros

Subject: Re: [PATCH] NFS: Reduce stack use in encode_exchange_id()

Thanks Jim, I'll test this and report back.

-dros

On Oct 26, 2012, at 11:06 PM, "Jim Rees" <[email protected]> wrote:

> For comment only. I have not tested this.
>
> encode_exchange_id() uses more stack space than necessary, giving a compile
> time warning. Reduce the size of the static buffer for implementation name.
>
> Signed-off-by: Jim Rees <[email protected]>
> ---
> fs/nfs/nfs4xdr.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
> index 8dba6bd..ccd1dde 100644
> --- a/fs/nfs/nfs4xdr.c
> +++ b/fs/nfs/nfs4xdr.c
> @@ -1700,12 +1700,15 @@ static void encode_bind_conn_to_session(struct xdr_stream *xdr,
> *p = 0; /* use_conn_in_rdma_mode = False */
> }
>
> +#define IMPL_NAME_LIMIT (sizeof(utsname()->sysname) + sizeof(utsname()->release) + \
> + sizeof(utsname()->version) + sizeof(utsname()->machine) + 8)
> +
> static void encode_exchange_id(struct xdr_stream *xdr,
> struct nfs41_exchange_id_args *args,
> struct compound_hdr *hdr)
> {
> __be32 *p;
> - char impl_name[NFS4_OPAQUE_LIMIT];
> + char impl_name[IMPL_NAME_LIMIT];
> int len = 0;
>
> encode_op_hdr(xdr, OP_EXCHANGE_ID, decode_exchange_id_maxsz, hdr);
> @@ -1720,7 +1723,7 @@ static void encode_exchange_id(struct xdr_stream *xdr,
> if (send_implementation_id &&
> sizeof(CONFIG_NFS_V4_1_IMPLEMENTATION_ID_DOMAIN) > 1 &&
> sizeof(CONFIG_NFS_V4_1_IMPLEMENTATION_ID_DOMAIN)
> - <= NFS4_OPAQUE_LIMIT + 1)
> + <= sizeof(impl_name) + 1)
> len = snprintf(impl_name, sizeof(impl_name), "%s %s %s %s",
> utsname()->sysname, utsname()->release,
> utsname()->version, utsname()->machine);
> --
> 1.7.9.5
>
> --
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