From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8DE0649DB90 for ; Mon, 21 Sep 2026 13:22:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789996963; cv=none; b=V/mh3cuaUV4jtAUqLkQt/yqygKysuZ7zBejQjuM9/fJzvD2AdaT+XM3qLx2R9evBWT53nMxi+7Crh5FyflR+fwdE8k+sotlfBbS4w0VI5oXxUlGUbvGwbqWo32uOtGHXA41VK13uiRWwngujyut+AnszWlNkko3Jlsag4bvOleg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789996963; c=relaxed/simple; bh=ndp0dKQygu7J0h1iI8KDpk9FrMqHmDCaIvKQ1w9o6z0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=YxXdjDniNZ1K3n9DChKHFWgF8MCJsPjwp7dY4laU/Yf7BokOVQsFNch5lEZltGr6B9QCG9IAxfcT3b/mr34g4eIF+Znyrsj2L+vENTm2KUM9mmjKObD5cP3Uj48mWmrlJdBLRqWeANWgsyh0JFd5YAI2TtRZMT+go0ndlbfE45Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TOqRx88G; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TOqRx88G" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 531CF1F000FF; Mon, 21 Sep 2026 13:22:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789996962; bh=Et0014LPxXBiOS7B11bhhTCvsKeh+lCl4607bnp0/c8=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=TOqRx88GvtmGW//8pAdjkD7XLhZC2DpRZ02lBLGw29bq5Q/k+5GN199jzqaG0WLjC bKgXnRszAMWbWYfpDgJJ+rf7rmUoyVKwWBsQ9YqPcaqCmUjseBVVjEd+UOnYhVRjBx XO1v2uOJYM3YQpfT3CR0A8Z0PPmrVhS5tgb5cUqpDFiEbh/T5T1nukMrf7LYxckq5F Zbh3rSPtpzE1h5/7XqJV2HEvJ9gHoupWER1fHONpDIlFJZhqU5AFnI8FxTU8IAlFLw EpYZzAfOYyF+1O5yF71+o14Nhazn/HFbS5554aWVyhNEA6C+fggC6Xt0Z1DbkzToRH u5fQzQPwSh2MA== From: Chuck Lever Date: Mon, 21 Sep 2026 09:22:29 -0400 Subject: [PATCH v6 03/12] SUNRPC: Assign a unique identifier to each svc_xprt Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260921-duplicate-reply-cache-v6-3-db5e13fd9944@kernel.org> References: <20260921-duplicate-reply-cache-v6-0-db5e13fd9944@kernel.org> In-Reply-To: <20260921-duplicate-reply-cache-v6-0-db5e13fd9944@kernel.org> To: Jeff Layton , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: Rick Macklem , linux-nfs@vger.kernel.org, Chuck Lever X-Mailer: b4 0.16-dev-da966 X-Developer-Signature: v=1; a=openpgp-sha256; l=4235; i=cel@kernel.org; h=from:subject:message-id; bh=ndp0dKQygu7J0h1iI8KDpk9FrMqHmDCaIvKQ1w9o6z0=; b=owEBbQKS/ZANAwAKATNqszNvZn+XAcsmYgBqsS+dCGyzLqFG8Bv5BIKK/yuGTgPyE4HEoVwX4 bcag4U0fSqJAjMEAAEKAB0WIQQosuWwEobfJDzyPv4zarMzb2Z/lwUCarEvnQAKCRAzarMzb2Z/ l36RD/40z3rTifWYzjdEgbRMR7+XWSjZeoTqOBHy7ZDikbiiXYy3ffkYniZC1d9Uvi1LoJeqHcG lyLuq15q1KEiS++l+dOzNhK2j3cFXERussSlUQOKPJCMpTHIBol7Uc861+Qrg9BjaaX3OdjUApO fNAcid4bl6LrggRpz1NMBzzrk+Pq4vZmIx2XKVJtSQEwo5lNZWQtRtNfs7D8nx1mtfH7VzYqhO4 4nT2MQ4xGM1XuZbU1MALkZ8Ufk4sJverNLaJH9Cxt16PtRRJ1rxw2dYqH4tgvaWZjRfP1bd9TAB agc57IaDJctmdEdHr/FnpbBlwK61mOnts3y6fRFsMuxXifqy01c+oA9rodCafpksL1PPZFDbUJp 8UZVPz+nXKvW7p+nV5Db4pa6+nZlqifDzc10Iv4Vx72xFSlT1u1u9d7RgWW0d7hAxwy5X6lOwbO mddOfud7tBgcucmaZ0azXrK1Nd2Hl7EWf+W1dRRBwI2YFq9CKWKObJrEniZEveVef0yMW+Vordf I/7KRkVFejDCXYbH4ukeT6E2BhiKrLn5gYZZC1r9PJiFDOgblGO9etcPBjkr1q8b3ekZZyid0z+ YR4Xd53RNkmIbdZjyVYkLiTmvSm/aYN5T+bbMP9uIibXXVQT3UefCf9lmIvF0tJgPGgoQlmPiKt d67/ueWQiYIo7fg== X-Developer-Key: i=cel@kernel.org; a=openpgp; fpr=28B2E5B01286DF243CF23EFE336AB3336F667F97 A consumer that associates state with a transport without holding a reference cannot detect ABA collisions: once a transport is freed, SLUB may hand out a new svc_xprt at the same address. Assign each transport a 64-bit identifier from a global sequential counter in svc_xprt_init(). The counter cannot wrap within the lifetime of a transport, so two live transports never share an identifier and a consumer needs no release when the transport is freed. The NFSD duplicate reply cache is the first consumer. Assisted-by: LLM Signed-off-by: Chuck Lever --- include/linux/sunrpc/svc_xprt.h | 1 + include/trace/events/sunrpc.h | 8 ++++++-- net/sunrpc/svc_xprt.c | 17 ++++++++++++++--- 3 files changed, 21 insertions(+), 5 deletions(-) diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h index 2af222f3ea2c..52082d8ea6dd 100644 --- a/include/linux/sunrpc/svc_xprt.h +++ b/include/linux/sunrpc/svc_xprt.h @@ -56,6 +56,7 @@ struct svc_xprt { struct svc_xprt_class *xpt_class; const struct svc_xprt_ops *xpt_ops; struct kref xpt_ref; + u64 xpt_id; ktime_t xpt_qtime; struct list_head xpt_list; struct lwq_node xpt_ready; diff --git a/include/trace/events/sunrpc.h b/include/trace/events/sunrpc.h index ff855197880d..77efe63d2c14 100644 --- a/include/trace/events/sunrpc.h +++ b/include/trace/events/sunrpc.h @@ -1986,7 +1986,8 @@ TRACE_EVENT(svc_xprt_create_err, __sockaddr(server, (x)->xpt_locallen) \ __sockaddr(client, (x)->xpt_remotelen) \ __field(unsigned long, flags) \ - __field(unsigned int, netns_ino) + __field(unsigned int, netns_ino) \ + __field(u64, xpt_id) #define SVC_XPRT_ENDPOINT_ASSIGNMENTS(x) \ do { \ @@ -1996,13 +1997,15 @@ TRACE_EVENT(svc_xprt_create_err, (x)->xpt_remotelen); \ __entry->flags = (x)->xpt_flags; \ __entry->netns_ino = (x)->xpt_net->ns.inum; \ + __entry->xpt_id = (x)->xpt_id; \ } while (0) #define SVC_XPRT_ENDPOINT_FORMAT \ - "server=%pISpc client=%pISpc flags=%s" + "server=%pISpc client=%pISpc xpt_id=%llu flags=%s" #define SVC_XPRT_ENDPOINT_VARARGS \ __get_sockaddr(server), __get_sockaddr(client), \ + __entry->xpt_id, \ show_svc_xprt_flags(__entry->flags) TRACE_EVENT(svc_xprt_enqueue, @@ -2024,6 +2027,7 @@ TRACE_EVENT(svc_xprt_enqueue, xprt->xpt_remotelen); __entry->flags = flags; __entry->netns_ino = xprt->xpt_net->ns.inum; + __entry->xpt_id = xprt->xpt_id; ), TP_printk(SVC_XPRT_ENDPOINT_FORMAT, SVC_XPRT_ENDPOINT_VARARGS) diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index d5634dd6d6cc..463ba8d77f0c 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -26,6 +26,8 @@ static unsigned int svc_rpc_per_connection_limit __read_mostly; module_param(svc_rpc_per_connection_limit, uint, 0644); +static atomic64_t svc_xprt_id_seq; + static struct svc_deferred_req *svc_deferred_dequeue(struct svc_xprt *xprt); static int svc_deferred_recv(struct svc_rqst *rqstp); @@ -190,9 +192,17 @@ void svc_xprt_put(struct svc_xprt *xprt) } EXPORT_SYMBOL_GPL(svc_xprt_put); -/* - * Called by transport drivers to initialize the transport independent - * portion of the transport instance. +/** + * svc_xprt_init - initialize transport-independent portion of a transport + * @net: network namespace in which the transport operates + * @xcl: transport class providing operations and metadata + * @xprt: svc_xprt to initialize + * @serv: RPC service that owns this transport + * + * @xprt->xpt_id is never reused: a 64-bit counter does not wrap + * within the lifetime of a transport. + * + * Context: Process context. May sleep. */ void svc_xprt_init(struct net *net, struct svc_xprt_class *xcl, struct svc_xprt *xprt, struct svc_serv *serv) @@ -210,6 +220,7 @@ void svc_xprt_init(struct net *net, struct svc_xprt_class *xcl, set_bit(XPT_BUSY, &xprt->xpt_flags); xprt->xpt_net = get_net_track(net, &xprt->ns_tracker, GFP_ATOMIC); strcpy(xprt->xpt_remotebuf, "uninitialized"); + xprt->xpt_id = atomic64_inc_return(&svc_xprt_id_seq); } EXPORT_SYMBOL_GPL(svc_xprt_init); -- 2.55.0