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 60FC74825B5 for ; Mon, 14 Sep 2026 14:45:45 +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=1789397147; cv=none; b=vFaA+S77Op1WqX+LodW3221GDEDj2RIySyrCfam7iuLG6xDoY4OaFEZ2dfypVXDyXSlv/uHzkKyWIi0ph7v2Za4DejP/fGQkrUh498VpQex1Ug6T7vMIsgUHOErQcXTMO3Yrjjho0b8KhRaJIQ2NncO9Ft5ndunO/cC0+pGtj1Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789397147; c=relaxed/simple; bh=NbPhePj7OhsWFcF01OXnR8JRAy2oQf++RQWow0+SBaE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=oxxNeB1IfGYQfQ1OmpdC6cPGmm3boRj+wiOmJ0qeJkzyuKvKqIHciJaPYFBVyYS6fjiYwJWgrqIwzcO/qHLuJd/fhnWEqYj/iom2RZzpvk+NHQALfnSvsp8cxu/OUF42QiVovx+NjTs++E0AgbKh5y/7zvkt9S9Nx7GVxHdb5No= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QpfztRgj; 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="QpfztRgj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45C851F00893; Mon, 14 Sep 2026 14:45:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789397144; bh=CcWJQVBJjWGgHipHk0/BN9QrIT5g5DOZcInTjxTLZGs=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=QpfztRgjiZd0tgrYMVnUKYFmF84teVtnTTErWyU0MJSHbYLGkJ7QMmUOaCB1KuDMT aK9SFbuCm9BdLgsfToW1l2Mi4ejT/ZftAsR4u6cnfjEX3yzN3JVv9b07aP8mlcPF7Z EpuuY4n+j918MXViEDT8faL+QSA6JpvCe/owCv10ZyChDfDpuRAZ/f8lxC+6tNfkR6 nVlkKXlWblGzKKJKUj7RyfqgdiSPJ+/451RsOQ80yDZAYpZ7tHt0SRd/RmK1xQV/x1 o4p6EgPM23i4PepP3FcS0lbtC7U0QLaZB5yDAn5gAYjaQJ9Bnd7cFcEiIrcIB1sP8P Js2wsBRZNdoVA== From: Chuck Lever Date: Mon, 14 Sep 2026 10:45:31 -0400 Subject: [PATCH v4 01/11] 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: <20260914-duplicate-reply-cache-v4-1-bcf9d2628a94@kernel.org> References: <20260914-duplicate-reply-cache-v4-0-bcf9d2628a94@kernel.org> In-Reply-To: <20260914-duplicate-reply-cache-v4-0-bcf9d2628a94@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=4353; i=cel@kernel.org; h=from:subject:message-id; bh=NbPhePj7OhsWFcF01OXnR8JRAy2oQf++RQWow0+SBaE=; b=owEBbQKS/ZANAwAKATNqszNvZn+XAcsmYgBqqAiW1zGBtxrdU35PQaitXv8RxzdzI38bZJfq1 WeO9YZAJ2KJAjMEAAEKAB0WIQQosuWwEobfJDzyPv4zarMzb2Z/lwUCaqgIlgAKCRAzarMzb2Z/ l7BpD/9hFnu3eHEfL7zjhDC3sa72un5EJlCkGUs5NJGQcUe/qVFxW415vF2lMAkAXl9mdywsRhE TxmEnSLRx2jng1rtfcc2exzYlBoF7QHawiMIaSE8eaCHQWtFrXSkEcUlEA3t6Lo0aRPdxmTjFuv hoEz/A9fGc5rWt7CjaMJHkfb93nfJ7qDF1bY5LlIaCFULNnxKBi3gS2+Audwv7KUe5YCAIAjqVF F8ZYVestFl+Q5ue8krI3GmW45+8dt+/Pcq3BbDV+1Dwabi214P7Q741HdEwL5cnnjXyhc5j83XM 3MxvW9Fmm72zoYhHL1DroTGNvyXBdlC8QkcN3AST7wmdSnSSsag7wGiQNwTnTAQcHf526vkNe09 I+viJzxFLuy2Q01/VF9Q6IaojN8Rffy3i/RTrOlWYMbxpBbS1eKJn+4FQIMs4uw2fg1NfJnKDbg R0JAIsX0fJSde7+abPYZ41qZd9PWwsfWcUNdU4Kz/Kc5Af6f8cMW0HKD4p4pGnclXgLDSOVCxaX mxvclegSgLCMX+ilOxijB+KrQXyCiWRMwTtWWazwAGKb+ZrpbK/M2EXZuyjIzmLuiTYcivvwzA1 HlmM9eNQW9s+znGvwZ1Tp/Qd4Z3NhEaX6W0Sn9RbawqYUfDSwmeZP8rdUS8ZCU6+h2FC7j9v4sT 3vvtNE6eesQsPiA== 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 32-bit identifier from a global sequential counter in svc_xprt_init(). An identifier is reused only after 2^32 further transports have been created, so a consumer whose association is shorter-lived than that needs no release when the transport is freed. The NFSD duplicate reply cache is the first consumer. A 32-bit value fits the padding in its cache entry, and a cache entry is retained for two minutes, not for 2^32 connections. 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..9f940c892eca 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; + u32 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..30d5fbb07e0a 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(u32, 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=%u 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..f836a7aebd64 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 atomic_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 reused only after 2^32 further transports have + * been initialized. + * + * 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 = atomic_inc_return(&svc_xprt_id_seq); } EXPORT_SYMBOL_GPL(svc_xprt_init); -- 2.55.0