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| author | Jeff Layton <jlayton@poochiereds.net> | 2015-06-03 16:14:26 -0400 |
|---|---|---|
| committer | Trond Myklebust <trond.myklebust@primarydata.com> | 2015-06-10 18:26:18 -0400 |
| commit | 8e2281330f9930bccf77cf04027ec60b6cc0fb34 (patch) | |
| tree | 6047f570e0ec5de10303d29326d6f62f5d0e2065 /net/sunrpc | |
| parent | 3c87ef6efb40f0e339d705c194b2224f854ec38e (diff) | |
| download | blackbird-obmc-linux-8e2281330f9930bccf77cf04027ec60b6cc0fb34.tar.gz blackbird-obmc-linux-8e2281330f9930bccf77cf04027ec60b6cc0fb34.zip | |
sunrpc: make xprt->swapper an atomic_t
Split xs_swapper into enable/disable functions and eliminate the
"enable" flag.
Currently, it's racy if you have multiple swapon/swapoff operations
running in parallel over the same xprt. Also fix it so that we only
set it to a memalloc socket on a 0->1 transition and only clear it
on a 1->0 transition.
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Diffstat (limited to 'net/sunrpc')
| -rw-r--r-- | net/sunrpc/clnt.c | 4 | ||||
| -rw-r--r-- | net/sunrpc/xprtsock.c | 38 |
2 files changed, 27 insertions, 15 deletions
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 0ba65156a62b..801044aeeedd 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -2495,7 +2495,7 @@ retry: goto retry; } - ret = xs_swapper(xprt, 1); + ret = xs_swapper_enable(xprt); xprt_put(xprt); } return ret; @@ -2522,7 +2522,7 @@ retry: goto retry; } - xs_swapper(xprt, 0); + xs_swapper_disable(xprt); xprt_put(xprt); } } diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index f344c0f8974c..6538e6fbb7ba 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -1961,31 +1961,43 @@ static void xs_set_memalloc(struct rpc_xprt *xprt) struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt); - if (xprt->swapper) + if (atomic_read(&xprt->swapper)) sk_set_memalloc(transport->inet); } /** - * xs_swapper - Tag this transport as being used for swap. + * xs_swapper_enable - Tag this transport as being used for swap. * @xprt: transport to tag - * @enable: enable/disable * + * Take a reference to this transport on behalf of the rpc_clnt, and + * optionally mark it for swapping if it wasn't already. */ -int xs_swapper(struct rpc_xprt *xprt, int enable) +int +xs_swapper_enable(struct rpc_xprt *xprt) { struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt); - int err = 0; - if (enable) { - xprt->swapper++; - xs_set_memalloc(xprt); - } else if (xprt->swapper) { - xprt->swapper--; - sk_clear_memalloc(transport->inet); - } + if (atomic_inc_return(&xprt->swapper) == 1) + sk_set_memalloc(transport->inet); + return 0; +} - return err; +/** + * xs_swapper_disable - Untag this transport as being used for swap. + * @xprt: transport to tag + * + * Drop a "swapper" reference to this xprt on behalf of the rpc_clnt. If the + * swapper refcount goes to 0, untag the socket as a memalloc socket. + */ +void +xs_swapper_disable(struct rpc_xprt *xprt) +{ + struct sock_xprt *transport = container_of(xprt, struct sock_xprt, + xprt); + + if (atomic_dec_and_test(&xprt->swapper)) + sk_clear_memalloc(transport->inet); } #else static void xs_set_memalloc(struct rpc_xprt *xprt) |
