From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olivier Dion via lttng-dev Subject: [PATCH lttng-ust] Add ctor/dtor priorities for tracepoints/events Date: Sat, 11 Jul 2020 11:29:07 -0400 Message-ID: <20200711152907.676582-1-olivier.dion@polymtl.ca> Reply-To: Olivier Dion Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.polymtl.ca (smtp.polymtl.ca [132.207.4.11]) by lists.lttng.org (Postfix) with ESMTPS id 4B3v1f3SZGz1Clm for ; Sat, 11 Jul 2020 11:28:06 -0400 (EDT) Received: from clara.localdomain (modemcable059.101-200-24.mc.videotron.ca [24.200.101.59]) (authenticated bits=0) by smtp.polymtl.ca (8.14.7/8.14.7) with ESMTP id 06BFRpPR009494 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Sat, 11 Jul 2020 11:28:05 -0400 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" To: lttng-dev@lists.lttng.org List-Id: lttng-dev@lists.lttng.org Some library might want to generate events in their ctor/dtor. If LTTng initialize/finalize its tracepoints/events at the wrong time, events are lost. Order of execution of the ctor/dtor is determined by priority. When some priorities are equal, the order of execution seems to be determined by: a) Order of appearance if in the same compilation unit b) Order of link if in different compilation units c) Order of load by ld-linux.so or dlopen(3) for share objects Also, using the constructor/destructor attributes without any priority will default to the _lowest_ priority 65535, at least for GCC. Thus, Providing the LTTNG_*_PRIO definitions allows users to set their ctor/dtor priority like so: ---------------------------------------------------------------------- ... __attribute__((constructor(LTTNG_CTOR_PRIO + 1))) ... __attribute__((destructor(LTTNG_DTOR_PRIO + 1))) ... ---------------------------------------------------------------------- or without any priority, that would also work. Note that LTTNG_*_PRIO are set to 101 because it is the _highest_ priority and 0 to 100 are reserved. Signed-off-by: Olivier Dion --- include/lttng/tracepoint.h | 8 ++++---- include/lttng/ust-compiler.h | 7 +++++++ include/lttng/ust-tracepoint-event.h | 4 ++-- 3 files changed, 13 insertions(+), 6 deletions(-) diff --git a/include/lttng/tracepoint.h b/include/lttng/tracepoint.h index d77a2fb2..70903757 100644 --- a/include/lttng/tracepoint.h +++ b/include/lttng/tracepoint.h @@ -318,7 +318,7 @@ __tracepoint__init_urcu_sym(void) } #endif -static void lttng_ust_notrace __attribute__((constructor)) +static void lttng_ust_notrace __attribute__((constructor(LTTNG_CTOR_PRIO))) __tracepoints__init(void); static void __tracepoints__init(void) @@ -340,7 +340,7 @@ __tracepoints__init(void) __tracepoint__init_urcu_sym(); } -static void lttng_ust_notrace __attribute__((destructor)) +static void lttng_ust_notrace __attribute__((destructor(LTTNG_DTOR_PRIO))) __tracepoints__destroy(void); static void __tracepoints__destroy(void) @@ -444,7 +444,7 @@ extern struct lttng_ust_tracepoint * const __stop___tracepoints_ptrs[] __attribute__((used, section("__tracepoints_ptrs"))) = \ &__tracepoint_##_provider##___##_name; -static void lttng_ust_notrace __attribute__((constructor)) +static void lttng_ust_notrace __attribute__((constructor(LTTNG_CTOR_PRIO))) __tracepoints__ptrs_init(void); static void __tracepoints__ptrs_init(void) @@ -488,7 +488,7 @@ __tracepoints__ptrs_init(void) } } -static void lttng_ust_notrace __attribute__((destructor)) +static void lttng_ust_notrace __attribute__((destructor(LTTNG_DTOR_PRIO))) __tracepoints__ptrs_destroy(void); static void __tracepoints__ptrs_destroy(void) diff --git a/include/lttng/ust-compiler.h b/include/lttng/ust-compiler.h index 1d04da1a..4f1b1a40 100644 --- a/include/lttng/ust-compiler.h +++ b/include/lttng/ust-compiler.h @@ -27,4 +27,11 @@ #define lttng_ust_notrace __attribute__((no_instrument_function)) #define LTTNG_PACKED __attribute__((__packed__)) +/* + * Value in range [0, 100] are reserved. Thus 101 is the higest + * priority that can be used. + */ +#define LTTNG_CTOR_PRIO 101 +#define LTTNG_DTOR_PRIO 101 + #endif /* _LTTNG_UST_COMPILER_H */ diff --git a/include/lttng/ust-tracepoint-event.h b/include/lttng/ust-tracepoint-event.h index 7890c247..cd45ae08 100644 --- a/include/lttng/ust-tracepoint-event.h +++ b/include/lttng/ust-tracepoint-event.h @@ -1009,7 +1009,7 @@ static int _TP_COMBINE_TOKENS(__probe_register_refcount___, TRACEPOINT_PROVIDER) /* Reset all macros within TRACEPOINT_EVENT */ #include -static void lttng_ust_notrace __attribute__((constructor)) +static void lttng_ust_notrace __attribute__((constructor(LTTNG_CTOR_PRIO))) _TP_COMBINE_TOKENS(__lttng_events_init__, TRACEPOINT_PROVIDER)(void); static void _TP_COMBINE_TOKENS(__lttng_events_init__, TRACEPOINT_PROVIDER)(void) @@ -1036,7 +1036,7 @@ _TP_COMBINE_TOKENS(__lttng_events_init__, TRACEPOINT_PROVIDER)(void) } } -static void lttng_ust_notrace __attribute__((destructor)) +static void lttng_ust_notrace __attribute__((destructor(LTTNG_DTOR_PRIO))) _TP_COMBINE_TOKENS(__lttng_events_exit__, TRACEPOINT_PROVIDER)(void); static void _TP_COMBINE_TOKENS(__lttng_events_exit__, TRACEPOINT_PROVIDER)(void) -- 2.27.0 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 X-Spam-Level: X-Spam-Status: No, score=-13.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6B5DDC433E2 for ; Sat, 11 Jul 2020 15:28:13 +0000 (UTC) Received: from lists.lttng.org (lists.lttng.org [167.114.26.123]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DEAC62075F for ; Sat, 11 Jul 2020 15:28:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.lttng.org header.i=@lists.lttng.org header.b="h9FlusTg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DEAC62075F Authentication-Results: mail.kernel.org; dmarc=pass (p=none dis=none) header.from=lists.lttng.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lttng-dev-bounces@lists.lttng.org Received: from lists-lttng01.efficios.com (localhost [IPv6:::1]) by lists.lttng.org (Postfix) with ESMTP id 4B3v1j02vyz1Cxn; Sat, 11 Jul 2020 11:28:08 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lists.lttng.org; s=default; t=1594481291; bh=1NH5qc43IidhylmZuG9ktE0Ck0mVvED9B+b9V7eDM3U=; h=To:Date:Subject:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:From; b=h9FlusTgirjA82HeTYLH2l2xo9OLzUYp1czAr+KZrjWe16ebBrgXMhtD07XHx3lkd gF/nlFHTlta0WckRJ4vmYPmdjO32tHYGZK3gHkcELA5/cuEKn+jKgp7z4p+09H0vj/ dh5SdYKy+hRmBLHCtN+Ykym7UwS3z7LFQt4qO9ngHhWO2HlBq0wikIjGPKIhpBxpJO ib4epg7dYIf//apW5SmKRq0E6jM5AoGapdGnmuYj0PyQ21OHRIp0/ivQlaCLr/lLkt pxrFdutH61kRmoy77Y3ZTIqT84iKZ2hQ8ezLM9z0O6TCGwo0QBrAgMKdH4ejMXQRN8 /4mpJSRHygA1Q== Received: from smtp.polymtl.ca (smtp.polymtl.ca [132.207.4.11]) by lists.lttng.org (Postfix) with ESMTPS id 4B3v1f3SZGz1Clm for ; Sat, 11 Jul 2020 11:28:06 -0400 (EDT) Received: from clara.localdomain (modemcable059.101-200-24.mc.videotron.ca [24.200.101.59]) (authenticated bits=0) by smtp.polymtl.ca (8.14.7/8.14.7) with ESMTP id 06BFRpPR009494 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Sat, 11 Jul 2020 11:28:05 -0400 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp.polymtl.ca 06BFRpPR009494 To: lttng-dev@lists.lttng.org Date: Sat, 11 Jul 2020 11:29:07 -0400 Message-ID: <20200711152907.676582-1-olivier.dion@polymtl.ca> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 X-Poly-FromMTA: (modemcable059.101-200-24.mc.videotron.ca [24.200.101.59]) at Sat, 11 Jul 2020 15:27:51 +0000 Subject: [lttng-dev] [PATCH lttng-ust] Add ctor/dtor priorities for tracepoints/events X-BeenThere: lttng-dev@lists.lttng.org X-Mailman-Version: 2.1.31 Precedence: list List-Id: LTTng development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Olivier Dion via lttng-dev Reply-To: Olivier Dion Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" Message-ID: <20200711152907.JR5JNZq-v3KxlSvK7oe6JSLAI6qtSwTP9msY3VTuibU@z> Some library might want to generate events in their ctor/dtor. If LTTng initialize/finalize its tracepoints/events at the wrong time, events are lost. Order of execution of the ctor/dtor is determined by priority. When some priorities are equal, the order of execution seems to be determined by: a) Order of appearance if in the same compilation unit b) Order of link if in different compilation units c) Order of load by ld-linux.so or dlopen(3) for share objects Also, using the constructor/destructor attributes without any priority will default to the _lowest_ priority 65535, at least for GCC. Thus, Providing the LTTNG_*_PRIO definitions allows users to set their ctor/dtor priority like so: ---------------------------------------------------------------------- ... __attribute__((constructor(LTTNG_CTOR_PRIO + 1))) ... __attribute__((destructor(LTTNG_DTOR_PRIO + 1))) ... ---------------------------------------------------------------------- or without any priority, that would also work. Note that LTTNG_*_PRIO are set to 101 because it is the _highest_ priority and 0 to 100 are reserved. Signed-off-by: Olivier Dion --- include/lttng/tracepoint.h | 8 ++++---- include/lttng/ust-compiler.h | 7 +++++++ include/lttng/ust-tracepoint-event.h | 4 ++-- 3 files changed, 13 insertions(+), 6 deletions(-) diff --git a/include/lttng/tracepoint.h b/include/lttng/tracepoint.h index d77a2fb2..70903757 100644 --- a/include/lttng/tracepoint.h +++ b/include/lttng/tracepoint.h @@ -318,7 +318,7 @@ __tracepoint__init_urcu_sym(void) } #endif -static void lttng_ust_notrace __attribute__((constructor)) +static void lttng_ust_notrace __attribute__((constructor(LTTNG_CTOR_PRIO))) __tracepoints__init(void); static void __tracepoints__init(void) @@ -340,7 +340,7 @@ __tracepoints__init(void) __tracepoint__init_urcu_sym(); } -static void lttng_ust_notrace __attribute__((destructor)) +static void lttng_ust_notrace __attribute__((destructor(LTTNG_DTOR_PRIO))) __tracepoints__destroy(void); static void __tracepoints__destroy(void) @@ -444,7 +444,7 @@ extern struct lttng_ust_tracepoint * const __stop___tracepoints_ptrs[] __attribute__((used, section("__tracepoints_ptrs"))) = \ &__tracepoint_##_provider##___##_name; -static void lttng_ust_notrace __attribute__((constructor)) +static void lttng_ust_notrace __attribute__((constructor(LTTNG_CTOR_PRIO))) __tracepoints__ptrs_init(void); static void __tracepoints__ptrs_init(void) @@ -488,7 +488,7 @@ __tracepoints__ptrs_init(void) } } -static void lttng_ust_notrace __attribute__((destructor)) +static void lttng_ust_notrace __attribute__((destructor(LTTNG_DTOR_PRIO))) __tracepoints__ptrs_destroy(void); static void __tracepoints__ptrs_destroy(void) diff --git a/include/lttng/ust-compiler.h b/include/lttng/ust-compiler.h index 1d04da1a..4f1b1a40 100644 --- a/include/lttng/ust-compiler.h +++ b/include/lttng/ust-compiler.h @@ -27,4 +27,11 @@ #define lttng_ust_notrace __attribute__((no_instrument_function)) #define LTTNG_PACKED __attribute__((__packed__)) +/* + * Value in range [0, 100] are reserved. Thus 101 is the higest + * priority that can be used. + */ +#define LTTNG_CTOR_PRIO 101 +#define LTTNG_DTOR_PRIO 101 + #endif /* _LTTNG_UST_COMPILER_H */ diff --git a/include/lttng/ust-tracepoint-event.h b/include/lttng/ust-tracepoint-event.h index 7890c247..cd45ae08 100644 --- a/include/lttng/ust-tracepoint-event.h +++ b/include/lttng/ust-tracepoint-event.h @@ -1009,7 +1009,7 @@ static int _TP_COMBINE_TOKENS(__probe_register_refcount___, TRACEPOINT_PROVIDER) /* Reset all macros within TRACEPOINT_EVENT */ #include -static void lttng_ust_notrace __attribute__((constructor)) +static void lttng_ust_notrace __attribute__((constructor(LTTNG_CTOR_PRIO))) _TP_COMBINE_TOKENS(__lttng_events_init__, TRACEPOINT_PROVIDER)(void); static void _TP_COMBINE_TOKENS(__lttng_events_init__, TRACEPOINT_PROVIDER)(void) @@ -1036,7 +1036,7 @@ _TP_COMBINE_TOKENS(__lttng_events_init__, TRACEPOINT_PROVIDER)(void) } } -static void lttng_ust_notrace __attribute__((destructor)) +static void lttng_ust_notrace __attribute__((destructor(LTTNG_DTOR_PRIO))) _TP_COMBINE_TOKENS(__lttng_events_exit__, TRACEPOINT_PROVIDER)(void); static void _TP_COMBINE_TOKENS(__lttng_events_exit__, TRACEPOINT_PROVIDER)(void) -- 2.27.0 _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev