| Message ID | 1541642697-33860-1-git-send-email-yuehaibing@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [net-next] SUNRPC: drop pointless static qualifier in xdr_get_next_encode_buffer() | expand |
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@huawei.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?
On Thu, Nov 08, 2018 at 03:13:25AM +0000, Trond Myklebust wrote: > 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. Applying for 4.20 and stable, thanks! > > > > Signed-off-by: YueHaibing <yuehaibing@huawei.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. Agreed. Looks like I introduced that in 3.16, over 5 years ago, so I'm a little surprised not to have seen a bug report that this would explain. Maybe it's just that the critical section is only a few lines of arithemtic at the end of the function. Also it only gets called when an xdr reply other than a read reaches the end of a page. So you'd need a lot of concurrent READDIRs of large directories or something. Still, I'd think it would be possible..... > Thank you, YueHaibing! > > Bruce, do you want to shepherd this one in? Yes, I've got 3 bugfixes queued up now, I should send them along later today or tomorrow. --b.
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;
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@huawei.com> --- net/sunrpc/xdr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)