From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f54.google.com (mail-wg0-f54.google.com [74.125.82.54]) by kanga.kvack.org (Postfix) with ESMTP id 130C86B006E for ; Sat, 30 May 2015 08:03:39 -0400 (EDT) Received: by wgez8 with SMTP id z8so81246948wge.0 for ; Sat, 30 May 2015 05:03:38 -0700 (PDT) Received: from mail-wi0-f177.google.com (mail-wi0-f177.google.com. [209.85.212.177]) by mx.google.com with ESMTPS id fz5si8733854wib.94.2015.05.30.05.03.35 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 30 May 2015 05:03:35 -0700 (PDT) Received: by wicmx19 with SMTP id mx19so34990617wic.0 for ; Sat, 30 May 2015 05:03:35 -0700 (PDT) From: Jeff Layton Subject: [PATCH 2/4] sunrpc: make xprt->swapper an atomic_t Date: Sat, 30 May 2015 08:03:11 -0400 Message-Id: <1432987393-15604-3-git-send-email-jeff.layton@primarydata.com> In-Reply-To: <1432987393-15604-1-git-send-email-jeff.layton@primarydata.com> References: <1432987393-15604-1-git-send-email-jeff.layton@primarydata.com> Sender: owner-linux-mm@kvack.org List-ID: To: trond.myklebust@primarydata.com Cc: linux-nfs@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman , Jerome Marchand 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 Signed-off-by: Jeff Layton --- include/linux/sunrpc/xprt.h | 5 +++-- net/sunrpc/clnt.c | 4 ++-- net/sunrpc/xprtsock.c | 38 +++++++++++++++++++++++++------------- 3 files changed, 30 insertions(+), 17 deletions(-) diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h index 8b93ef53df3c..26b1624128ec 100644 --- a/include/linux/sunrpc/xprt.h +++ b/include/linux/sunrpc/xprt.h @@ -180,7 +180,7 @@ struct rpc_xprt { atomic_t num_reqs; /* total slots */ unsigned long state; /* transport state */ unsigned char resvport : 1; /* use a reserved port */ - unsigned int swapper; /* we're swapping over this + atomic_t swapper; /* we're swapping over this transport */ unsigned int bind_index; /* bind function index */ @@ -345,7 +345,8 @@ void xprt_release_rqst_cong(struct rpc_task *task); void xprt_disconnect_done(struct rpc_xprt *xprt); void xprt_force_disconnect(struct rpc_xprt *xprt); void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie); -int xs_swapper(struct rpc_xprt *xprt, int enable); +int xs_swapper_enable(struct rpc_xprt *xprt); +void xs_swapper_disable(struct rpc_xprt *xprt); bool xprt_lock_connect(struct rpc_xprt *, struct rpc_task *, void *); void xprt_unlock_connect(struct rpc_xprt *, void *); diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 383cb778179f..804a75e71e84 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -2492,7 +2492,7 @@ retry: goto retry; } - ret = xs_swapper(xprt, 1); + ret = xs_swapper_enable(xprt); xprt_put(xprt); } return ret; @@ -2519,7 +2519,7 @@ 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 b29703996028..a2861bbfd319 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -1966,31 +1966,43 @@ 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) -- 2.4.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org