netdev - Re: [PATCH net-next] SUNRPC: drop pointless static qualifier in xdr_get_next_encode

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Message-ID: <d23105929adb66c626d382525adef77265585404.camel@hammerspace.com>
Date:   Thu, 8 Nov 2018 03:13:25 +0000
From:   Trond Myklebust <trondmy@...merspace.com>
To:     "yuehaibing@...wei.com" <yuehaibing@...wei.com>,
        "anna.schumaker@...app.com" <anna.schumaker@...app.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "bfields@...ldses.org" <bfields@...ldses.org>,
        "jlayton@...nel.org" <jlayton@...nel.org>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
        "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH net-next] SUNRPC: drop pointless static qualifier in
 xdr_get_next_encode_buffer()

On Thu, 2018-11-08 at 02:04 +0000, YueHaibing wrote:
> There is no need to have the '__be32 *p' variable static since new
> value
> always be assigned before use it.
> 
> Signed-off-by: YueHaibing <yuehaibing@...wei.com>
> ---
>  net/sunrpc/xdr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
> index 2bbb8d3..d80b156 100644
> --- a/net/sunrpc/xdr.c
> +++ b/net/sunrpc/xdr.c
> @@ -546,7 +546,7 @@ void xdr_commit_encode(struct xdr_stream *xdr)
>  static __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr,
>  		size_t nbytes)
>  {
> -	static __be32 *p;
> +	__be32 *p;
>  	int space_left;
>  	int frag1bytes, frag2bytes;
> 

Ouch, that's a really nasty bug that could definitely cause corruption
if you have 2 threads simultaneously calling this function! This really
deserves to be a stable patch.

Thank you, YueHaibing!

Bruce, do you want to shepherd this one in?

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@...merspace.com