From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 38193C433EF for ; Sun, 12 Jun 2022 23:46:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237909AbiFLXqt (ORCPT ); Sun, 12 Jun 2022 19:46:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52802 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232350AbiFLXqr (ORCPT ); Sun, 12 Jun 2022 19:46:47 -0400 Received: from nautica.notk.org (ipv6.notk.org [IPv6:2001:41d0:1:7a93::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 29E5733E90; Sun, 12 Jun 2022 16:46:46 -0700 (PDT) Received: by nautica.notk.org (Postfix, from userid 108) id 59219C021; Mon, 13 Jun 2022 01:46:44 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=codewreck.org; s=2; t=1655077604; bh=2pvlijFDTdPy9Af9WUD9+Wbr74cNH9134iAYt88GOw8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UuXZzdMpCQ09shJr9vF+fojJQ74BKY8yQzfvnxH5xDnKW3clFGVUummVSi5sRDfyZ olP6thlDBnF1d/9N3dZiJdZ3z9ZUGj5/rbfCgKSYUzpf7AnFtN/ysDcEhuWzMtD0HG PsDRke7ctH+zolmky3t55uC5qjegTeSzo9E498LIBp91Kprlx0/KaZLAEKU+MzrlBM GEgbmDB+Zb5REleAZUH2nmgrtN+OYjN86UNNQ/L+I+IBeo33WOlBmlq2WdcvlP2anF qg8c5+WVgYX+LdVLWsSSYy4meN0+59BxuQ235DGPEj4QJUj8ZWuWJ0VApyLriUYmVX crh+OW+OZ1hbA== Received: from odin.codewreck.org (localhost [127.0.0.1]) by nautica.notk.org (Postfix) with ESMTPS id 356DDC009; Mon, 13 Jun 2022 01:46:38 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=codewreck.org; s=2; t=1655077602; bh=2pvlijFDTdPy9Af9WUD9+Wbr74cNH9134iAYt88GOw8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xhUREBEUmhaehV0h9eJmC0PfubUWASYQ1mb+vGrNXfqTugLMZJyxa4dYrnhApTfsN P0DoTY4aeZ/QIs9zSUe4FIvFWcM/moUAPmeSBAxldYHzQ0zqd+cV/mk4f9rkQKbRbK iVx3T3n4RkadZa0CnpwcHuegv3Dz/5fWBT6aILy5LM3ATs8Q5uO5TS3zSpX+y/aI5F O6i6KVSYr+faQNACtHlctsmyn+U0bAE1oAg9Pzru1PUPKrznfNYlpU/In62PNrguRL 0BIzmjj0F+y/Zdi+RVg+YlCfhl6pfXnjjr3FDgFg9gcmuBnwfiM8c7MhlYswb5reaT wrYeOOIl6QEEw== Received: from localhost (odin.codewreck.org [local]) by odin.codewreck.org (OpenSMTPD) with ESMTPA id 498e4e6d; Sun, 12 Jun 2022 23:46:36 +0000 (UTC) From: Dominique Martinet To: Christian Schoenebeck , Tyler Hicks , Eric Van Hensbergen , Latchesar Ionkov , Dominique Martinet , "David S. Miller" , Jakub Kicinski , Paolo Abeni , Steven Rostedt , Ingo Molnar Cc: v9fs-developer@lists.sourceforge.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH v2 05/06] 9p fid refcount: add a 9p_fid_ref tracepoint Date: Mon, 13 Jun 2022 08:46:34 +0900 Message-Id: <20220612234634.1559778-1-asmadeus@codewreck.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220612184659.6dff5107@rorschach.local.home> References: <20220612184659.6dff5107@rorschach.local.home> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This adds a tracepoint event for 9p fid lifecycle tracing: when a fid is created, its reference count increased/decreased, and freed. The new 9p_fid_ref tracepoint should help anyone wishing to debug any fid problem such as missing clunk (destroy) or use-after-free. Signed-off-by: Dominique Martinet --- Steven, thank you for the review! By changelog, is the commit message enough? I've applied your suggestion to use DECLARE_TRACEPOINT + enable checks, it doesn't seem to have many users but it looks good to me. v1-v2: - added rationale to commit message - adjusted to use DECLARE_TRACEPOINT + tracepoint_enable() in header include/net/9p/client.h | 13 +++++++++++ include/trace/events/9p.h | 48 +++++++++++++++++++++++++++++++++++++++ net/9p/client.c | 17 +++++++++++++- 3 files changed, 77 insertions(+), 1 deletion(-) diff --git a/include/net/9p/client.h b/include/net/9p/client.h index 9fd38d674057..6f347983705d 100644 --- a/include/net/9p/client.h +++ b/include/net/9p/client.h @@ -11,6 +11,7 @@ #include #include +#include /* Number of requests per row */ #define P9_ROW_MAXTAG 255 @@ -237,8 +238,17 @@ static inline int p9_req_try_get(struct p9_req_t *r) int p9_req_put(struct p9_req_t *r); +/* We cannot have the real tracepoints in header files, + * use a wrapper function */ +DECLARE_TRACEPOINT(9p_fid_ref); +void do_trace_9p_fid_get(struct p9_fid *fid); +void do_trace_9p_fid_put(struct p9_fid *fid); + static inline struct p9_fid *p9_fid_get(struct p9_fid *fid) { + if (tracepoint_enabled(9p_fid_ref)) + do_trace_9p_fid_get(fid); + refcount_inc(&fid->count); return fid; @@ -249,6 +259,9 @@ static inline int p9_fid_put(struct p9_fid *fid) if (!fid || IS_ERR(fid)) return 0; + if (tracepoint_enabled(9p_fid_ref)) + do_trace_9p_fid_put(fid); + if (!refcount_dec_and_test(&fid->count)) return 0; diff --git a/include/trace/events/9p.h b/include/trace/events/9p.h index 78c5608a1648..4dfa6d7f83ba 100644 --- a/include/trace/events/9p.h +++ b/include/trace/events/9p.h @@ -77,6 +77,13 @@ EM( P9_TWSTAT, "P9_TWSTAT" ) \ EMe(P9_RWSTAT, "P9_RWSTAT" ) + +#define P9_FID_REFTYPE \ + EM( P9_FID_REF_CREATE, "create " ) \ + EM( P9_FID_REF_GET, "get " ) \ + EM( P9_FID_REF_PUT, "put " ) \ + EMe(P9_FID_REF_DESTROY, "destroy" ) + /* Define EM() to export the enums to userspace via TRACE_DEFINE_ENUM() */ #undef EM #undef EMe @@ -84,6 +91,21 @@ #define EMe(a, b) TRACE_DEFINE_ENUM(a); P9_MSG_T +P9_FID_REFTYPE + +/* And also use EM/EMe to define helper enums -- once */ +#ifndef __9P_DECLARE_TRACE_ENUMS_ONLY_ONCE +#define __9P_DECLARE_TRACE_ENUMS_ONLY_ONCE +#undef EM +#undef EMe +#define EM(a, b) a, +#define EMe(a, b) a + +enum p9_fid_reftype { + P9_FID_REFTYPE +} __mode(byte); + +#endif /* * Now redefine the EM() and EMe() macros to map the enums to the strings @@ -96,6 +118,8 @@ P9_MSG_T #define show_9p_op(type) \ __print_symbolic(type, P9_MSG_T) +#define show_9p_fid_reftype(type) \ + __print_symbolic(type, P9_FID_REFTYPE) TRACE_EVENT(9p_client_req, TP_PROTO(struct p9_client *clnt, int8_t type, int tag), @@ -168,6 +192,30 @@ TRACE_EVENT(9p_protocol_dump, __entry->tag, 0, __entry->line, 16, __entry->line + 16) ); + +TRACE_EVENT(9p_fid_ref, + TP_PROTO(struct p9_fid *fid, __u8 type), + + TP_ARGS(fid, type), + + TP_STRUCT__entry( + __field( int, fid ) + __field( int, refcount ) + __field( __u8, type ) + ), + + TP_fast_assign( + __entry->fid = fid->fid; + __entry->refcount = refcount_read(&fid->count); + __entry->type = type; + ), + + TP_printk("%s fid %d, refcount %d", + show_9p_fid_reftype(__entry->type), + __entry->fid, __entry->refcount) +); + + #endif /* _TRACE_9P_H */ /* This part must be outside protection */ diff --git a/net/9p/client.c b/net/9p/client.c index f3eb280c7d9d..06d67a02d431 100644 --- a/net/9p/client.c +++ b/net/9p/client.c @@ -907,8 +907,10 @@ static struct p9_fid *p9_fid_create(struct p9_client *clnt) GFP_NOWAIT); spin_unlock_irq(&clnt->lock); idr_preload_end(); - if (!ret) + if (!ret) { + trace_9p_fid_ref(fid, P9_FID_REF_CREATE); return fid; + } kfree(fid); return NULL; @@ -920,6 +922,7 @@ static void p9_fid_destroy(struct p9_fid *fid) unsigned long flags; p9_debug(P9_DEBUG_FID, "fid %d\n", fid->fid); + trace_9p_fid_ref(fid, P9_FID_REF_DESTROY); clnt = fid->clnt; spin_lock_irqsave(&clnt->lock, flags); idr_remove(&clnt->fids, fid->fid); @@ -928,6 +931,18 @@ static void p9_fid_destroy(struct p9_fid *fid) kfree(fid); } +void do_trace_9p_fid_get(struct p9_fid *fid) +{ + trace_9p_fid_ref(fid, P9_FID_REF_GET); +} +EXPORT_SYMBOL(do_trace_9p_fid_get); + +void do_trace_9p_fid_put(struct p9_fid *fid) +{ + trace_9p_fid_ref(fid, P9_FID_REF_PUT); +} +EXPORT_SYMBOL(do_trace_9p_fid_put); + static int p9_client_version(struct p9_client *c) { int err = 0; -- 2.35.1