From nobody Thu Apr 9 07:52:26 2026 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 2BE09C433FE for ; Thu, 3 Nov 2022 17:11:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231800AbiKCRK5 (ORCPT ); Thu, 3 Nov 2022 13:10:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37526 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231418AbiKCRKe (ORCPT ); Thu, 3 Nov 2022 13:10:34 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 3FD571EAE5 for ; Thu, 3 Nov 2022 10:09:19 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 421E223A; Thu, 3 Nov 2022 10:09:25 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id DAC3B3F5A1; Thu, 3 Nov 2022 10:09:17 -0700 (PDT) From: Mark Rutland To: linux-kernel@vger.kernel.org Cc: mark.rutland@arm.com, mhiramat@kernel.org, revest@chromium.org, rostedt@goodmis.org Subject: [PATCH 1/3] ftrace: maintain samples/ftrace Date: Thu, 3 Nov 2022 17:09:05 +0000 Message-Id: <20221103170907.931465-2-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221103170907.931465-1-mark.rutland@arm.com> References: <20221103170907.931465-1-mark.rutland@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" There's no entry in MAINTAINERS for samples/ftrace. Add one so that the FTRACE maintainers are kept in the loop. Signed-off-by: Mark Rutland Cc: Masami Hiramatsu Cc: Steven Rostedt --- MAINTAINERS | 1 + 1 file changed, 1 insertion(+) diff --git a/MAINTAINERS b/MAINTAINERS index cf0f185023724..e2666b1976f5e 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8462,6 +8462,7 @@ F: kernel/trace/fgraph.c F: arch/*/*/*/*ftrace* F: arch/*/*/*ftrace* F: include/*/ftrace.h +F: samples/ftrace =20 FUNGIBLE ETHERNET DRIVERS M: Dimitris Michailidis --=20 2.30.2 From nobody Thu Apr 9 07:52:26 2026 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 07925C433FE for ; Thu, 3 Nov 2022 17:11:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232115AbiKCRLC (ORCPT ); Thu, 3 Nov 2022 13:11:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37532 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232048AbiKCRKe (ORCPT ); Thu, 3 Nov 2022 13:10:34 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 16FA4DEB2 for ; Thu, 3 Nov 2022 10:09:21 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1CB4811FB; Thu, 3 Nov 2022 10:09:27 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id BEB313F5A1; Thu, 3 Nov 2022 10:09:19 -0700 (PDT) From: Mark Rutland To: linux-kernel@vger.kernel.org Cc: mark.rutland@arm.com, mhiramat@kernel.org, revest@chromium.org, rostedt@goodmis.org Subject: [PATCH 2/3] ftrace: export ftrace_free_filter() to modules Date: Thu, 3 Nov 2022 17:09:06 +0000 Message-Id: <20221103170907.931465-3-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221103170907.931465-1-mark.rutland@arm.com> References: <20221103170907.931465-1-mark.rutland@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Setting filters on an ftrace ops results in some memory being allocated for the filter hashes, which must be freed before the ops can be freed. This can be done by removing every individual element of the hash by calling ftrace_set_filter_ip() or ftrace_set_filter_ips() with `remove` set, but this is somewhat error prone as it's easy to forget to remove an element. Make it easier to clean this up by exporting ftrace_free_filter(), which can be used to clean up all of the filter hashes after an ftrace_ops has been unregistered. Using this, fix the ftrace-direct* samples to free hashes prior to being unloaded. All other code either removes individual filters explicitly or is built-in and already calls ftrace_free_filter(). Signed-off-by: Mark Rutland Cc: Florent Revest Cc: Masami Hiramatsu Cc: Steven Rostedt Reviewed-by: Steven Rostedt (Google) --- kernel/trace/ftrace.c | 23 ++++++++++++++++++++- samples/ftrace/ftrace-direct-multi-modify.c | 1 + samples/ftrace/ftrace-direct-multi.c | 1 + 3 files changed, 24 insertions(+), 1 deletion(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index fbf2543111c05..1ecdda1df6d47 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1248,12 +1248,17 @@ static void free_ftrace_hash_rcu(struct ftrace_hash= *hash) call_rcu(&hash->rcu, __free_ftrace_hash_rcu); } =20 +/** + * ftrace_free_filter - remove all filters for an ftrace_ops + * @ops - the ops to remove the filters from + */ void ftrace_free_filter(struct ftrace_ops *ops) { ftrace_ops_init(ops); free_ftrace_hash(ops->func_hash->filter_hash); free_ftrace_hash(ops->func_hash->notrace_hash); } +EXPORT_SYMBOL_GPL(ftrace_free_filter); =20 static struct ftrace_hash *alloc_ftrace_hash(int size_bits) { @@ -5837,6 +5842,10 @@ EXPORT_SYMBOL_GPL(modify_ftrace_direct_multi); * * Filters denote which functions should be enabled when tracing is enabled * If @ip is NULL, it fails to update filter. + * + * This can allocate memory which must be freed before @ops can be freed, + * either by remvoing eached filtered addr or by using + * ftrace_free_filter(@ops). */ int ftrace_set_filter_ip(struct ftrace_ops *ops, unsigned long ip, int remove, int reset) @@ -5856,7 +5865,11 @@ EXPORT_SYMBOL_GPL(ftrace_set_filter_ip); * * Filters denote which functions should be enabled when tracing is enabled * If @ips array or any ip specified within is NULL , it fails to update f= ilter. - */ + * + * This can allocate memory which must be freed before @ops can be freed, + * either by remvoing eached filtered addr or by using + * ftrace_free_filter(@ops). +*/ int ftrace_set_filter_ips(struct ftrace_ops *ops, unsigned long *ips, unsigned int cnt, int remove, int reset) { @@ -5898,6 +5911,10 @@ ftrace_set_regex(struct ftrace_ops *ops, unsigned ch= ar *buf, int len, * * Filters denote which functions should be enabled when tracing is enable= d. * If @buf is NULL and reset is set, all functions will be enabled for tra= cing. + * + * This can allocate memory which must be freed before @ops can be freed, + * either by remvoing eached filtered addr or by using + * ftrace_free_filter(@ops). */ int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf, int len, int reset) @@ -5917,6 +5934,10 @@ EXPORT_SYMBOL_GPL(ftrace_set_filter); * Notrace Filters denote which functions should not be enabled when traci= ng * is enabled. If @buf is NULL and reset is set, all functions will be ena= bled * for tracing. + * + * This can allocate memory which must be freed before @ops can be freed, + * either by remvoing eached filtered addr or by using + * ftrace_free_filter(@ops). */ int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf, int len, int reset) diff --git a/samples/ftrace/ftrace-direct-multi-modify.c b/samples/ftrace/f= trace-direct-multi-modify.c index d52370cad0b6e..a825dbd2c9cfd 100644 --- a/samples/ftrace/ftrace-direct-multi-modify.c +++ b/samples/ftrace/ftrace-direct-multi-modify.c @@ -152,6 +152,7 @@ static void __exit ftrace_direct_multi_exit(void) { kthread_stop(simple_tsk); unregister_ftrace_direct_multi(&direct, my_tramp); + ftrace_free_filter(&direct); } =20 module_init(ftrace_direct_multi_init); diff --git a/samples/ftrace/ftrace-direct-multi.c b/samples/ftrace/ftrace-d= irect-multi.c index ec1088922517d..d955a26506053 100644 --- a/samples/ftrace/ftrace-direct-multi.c +++ b/samples/ftrace/ftrace-direct-multi.c @@ -79,6 +79,7 @@ static int __init ftrace_direct_multi_init(void) static void __exit ftrace_direct_multi_exit(void) { unregister_ftrace_direct_multi(&direct, (unsigned long) my_tramp); + ftrace_free_filter(&direct); } =20 module_init(ftrace_direct_multi_init); --=20 2.30.2 From nobody Thu Apr 9 07:52:26 2026 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 E18FEC4332F for ; Thu, 3 Nov 2022 17:11:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229826AbiKCRLI (ORCPT ); Thu, 3 Nov 2022 13:11:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37522 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232049AbiKCRKe (ORCPT ); Thu, 3 Nov 2022 13:10:34 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id F2A8AB33 for ; Thu, 3 Nov 2022 10:09:22 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 01A2D12FC; Thu, 3 Nov 2022 10:09:29 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id A243A3F5A1; Thu, 3 Nov 2022 10:09:21 -0700 (PDT) From: Mark Rutland To: linux-kernel@vger.kernel.org Cc: mark.rutland@arm.com, mhiramat@kernel.org, revest@chromium.org, rostedt@goodmis.org Subject: [PATCH 3/3] ftrace: add sample with custom ops Date: Thu, 3 Nov 2022 17:09:07 +0000 Message-Id: <20221103170907.931465-4-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221103170907.931465-1-mark.rutland@arm.com> References: <20221103170907.931465-1-mark.rutland@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" When reworking core ftrace code or architectural ftrace code, it's often necessary to test/analyse/benchmark a number of ftrace_ops configurations. This patch adds a module which can be used to explore some of those configurations. I'm using this to benchmark various options for changing the way trampolines and handling of ftrace_ops work on arm64. Signed-off-by: Mark Rutland Cc: Florent Revest Cc: Masami Hiramatsu Cc: Steven Rostedt --- samples/Kconfig | 7 + samples/Makefile | 1 + samples/ftrace/Makefile | 1 + samples/ftrace/ftrace-ops.c | 252 ++++++++++++++++++++++++++++++++++++ 4 files changed, 261 insertions(+) create mode 100644 samples/ftrace/ftrace-ops.c diff --git a/samples/Kconfig b/samples/Kconfig index 0d81c00289ee3..daf14c35f071d 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -46,6 +46,13 @@ config SAMPLE_FTRACE_DIRECT_MULTI that hooks to wake_up_process and schedule, and prints the function addresses. =20 +config SAMPLE_FTRACE_OPS + tristate "Build custom ftrace ops example" + depends on FUNCTION_TRACER + help + This builds an ftrace ops example that hooks two functions and + measures the time taken to invoke one function a number of times. + config SAMPLE_TRACE_ARRAY tristate "Build sample module for kernel access to Ftrace instance= ss" depends on EVENT_TRACING && m diff --git a/samples/Makefile b/samples/Makefile index 9832ef3f8fcba..7cb632ef88eeb 100644 --- a/samples/Makefile +++ b/samples/Makefile @@ -24,6 +24,7 @@ obj-$(CONFIG_SAMPLE_TRACE_CUSTOM_EVENTS) +=3D trace_event= s/ obj-$(CONFIG_SAMPLE_TRACE_PRINTK) +=3D trace_printk/ obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) +=3D ftrace/ obj-$(CONFIG_SAMPLE_FTRACE_DIRECT_MULTI) +=3D ftrace/ +obj-$(CONFIG_SAMPLE_FTRACE_OPS) +=3D ftrace/ obj-$(CONFIG_SAMPLE_TRACE_ARRAY) +=3D ftrace/ subdir-$(CONFIG_SAMPLE_UHID) +=3D uhid obj-$(CONFIG_VIDEO_PCI_SKELETON) +=3D v4l/ diff --git a/samples/ftrace/Makefile b/samples/ftrace/Makefile index faf8cdb79c5f4..589baf2ec4e3d 100644 --- a/samples/ftrace/Makefile +++ b/samples/ftrace/Makefile @@ -5,6 +5,7 @@ obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) +=3D ftrace-direct-too.o obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) +=3D ftrace-direct-modify.o obj-$(CONFIG_SAMPLE_FTRACE_DIRECT_MULTI) +=3D ftrace-direct-multi.o obj-$(CONFIG_SAMPLE_FTRACE_DIRECT_MULTI) +=3D ftrace-direct-multi-modify.o +obj-$(CONFIG_SAMPLE_FTRACE_OPS) +=3D ftrace-ops.o =20 CFLAGS_sample-trace-array.o :=3D -I$(src) obj-$(CONFIG_SAMPLE_TRACE_ARRAY) +=3D sample-trace-array.o diff --git a/samples/ftrace/ftrace-ops.c b/samples/ftrace/ftrace-ops.c new file mode 100644 index 0000000000000..aa883ad4fbe27 --- /dev/null +++ b/samples/ftrace/ftrace-ops.c @@ -0,0 +1,252 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include + +#include + +/* + * Arbitrary large value chosen to be sufficiently large to minimize noise= but + * sufficiently small to complete quickly. + */ +unsigned int nr_function_calls =3D 100000; +module_param(nr_function_calls, uint, 0); +MODULE_PARM_DESC(nr_function_calls, "How many times to call the relevant t= racee"); + +/* + * The number of ops associated with a call site affects whether a tracer = can + * be called directly or whether it's necessary to go via the list func, w= hich + * can be significantly more expensive. + */ +unsigned int nr_ops_relevant =3D 1; +module_param(nr_ops_relevant, uint, 0); +MODULE_PARM_DESC(nr_ops_relevant, "How many ftrace_ops to associate with t= he relevant tracee"); + +/* + * On architectures where all call sites share the same trampoline, having + * tracers enabled for distinct functions can force the use of the list fu= nc + * and incur overhead for all call sites. + */ +unsigned int nr_ops_irrelevant =3D 0; +module_param(nr_ops_irrelevant, uint, 0); +MODULE_PARM_DESC(nr_ops_irrelevant, "How many ftrace_ops to associate with= the irrelevant tracee"); + +/* + * On architectures with DYNAMIC_FTRACE_WITH_REGS, saving the full pt_regs= can + * be more expensive than only saving the minimal necessary regs. + */ +bool save_regs =3D false; +module_param(save_regs, bool, 0); +MODULE_PARM_DESC(regs, "Register ops with FTRACE_OPS_FL_SAVE_REGS (save al= l registers in the trampoline)"); + +bool assist_recursion =3D false; +module_param(assist_recursion, bool, 0); +MODULE_PARM_DESC(assist_reursion, "Register ops with FTRACE_OPS_FL_RECURSI= ON"); + +bool assist_rcu =3D false; +module_param(assist_rcu, bool, 0); +MODULE_PARM_DESC(assist_reursion, "Register ops with FTRACE_OPS_FL_RCU"); + +/* + * By default, a trivial tracer is used which immediately returns to mimim= ize + * overhead. Sometimes a consistency check using a more expensive tracer is + * desireable. + */ +bool check_count =3D false; +module_param(check_count, bool, 0); +MODULE_PARM_DESC(check_count, "Check that tracers are called the expected = number of times\n"); + +/* + * Usually it's not interesting to leave the ops registered after the test + * runs, but sometimes it can be useful to leave them registered so that t= hey + * can be inspected through the tracefs 'enabled_functions' file. + */ +bool persist =3D false; +module_param(persist, bool, 0); +MODULE_PARM_DESC(persist, "Successfully load module and leave ftrace ops r= egistered after test completes\n"); + +/* + * Marked as noinline to ensure that an out-of-line traceable copy is + * generated by the compiler. + * + * The barrier() ensures the compiler won't elide calls by determining the= re + * are no side-effects. + */ +static noinline void tracee_relevant(void) +{ + barrier(); +} + +/* + * Marked as noinline to ensure that an out-of-line traceable copy is + * generated by the compiler. + * + * The barrier() ensures the compiler won't elide calls by determining the= re + * are no side-effects. + */ +static noinline void tracee_irrelevant(void) +{ + barrier(); +} + +struct sample_ops { + struct ftrace_ops ops; + unsigned int count; +}; + +static void ops_func_nop(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *op, + struct ftrace_regs *fregs) +{ + /* do nothing */ +} + +static void ops_func_count(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *op, + struct ftrace_regs *fregs) +{ + struct sample_ops *self; + + self =3D container_of(op, struct sample_ops, ops); + self->count++; +} + +struct sample_ops *ops_relevant; +struct sample_ops *ops_irrelevant; + +static struct sample_ops *ops_alloc_init(void *tracee, ftrace_func_t func, + unsigned long flags, int nr) +{ + struct sample_ops *ops; + + ops =3D kcalloc(nr, sizeof(*ops), GFP_KERNEL); + if (WARN_ON_ONCE(!ops)) + return NULL; + + for (unsigned int i =3D 0; i < nr; i++) { + ops[i].ops.func =3D func; + ops[i].ops.flags =3D flags; + WARN_ON_ONCE(ftrace_set_filter_ip(&ops[i].ops, (unsigned long)tracee, 0,= 0)); + WARN_ON_ONCE(register_ftrace_function(&ops[i].ops)); + } + + return ops; +} + +static void ops_destroy(struct sample_ops *ops, int nr) +{ + if (!ops) + return; + + for (unsigned int i =3D 0; i < nr; i++) { + WARN_ON_ONCE(unregister_ftrace_function(&ops[i].ops)); + ftrace_free_filter(&ops[i].ops); + } + + kfree(ops); +} + +static void ops_check(struct sample_ops *ops, int nr, + unsigned int expected_count) +{ + if (!ops || !check_count) + return; + + for (unsigned int i =3D 0; i < nr; i++) { + if (ops->count =3D=3D expected_count) + continue; + pr_warn("Counter called %u times (expected %u)\n", + ops->count, expected_count); + } +} + +ftrace_func_t tracer_relevant =3D ops_func_nop; +ftrace_func_t tracer_irrelevant =3D ops_func_nop; + +static int __init ftrace_ops_sample_init(void) +{ + unsigned long flags =3D 0; + ktime_t start, end; + u64 period; + + if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && save_regs) { + pr_info("this kernel does not support saving registers\n"); + save_regs =3D false; + } else if (save_regs) { + flags |=3D FTRACE_OPS_FL_SAVE_REGS; + } + + if (assist_recursion) + flags |=3D FTRACE_OPS_FL_RECURSION; + + if (assist_rcu) + flags |=3D FTRACE_OPS_FL_RCU; + + if (check_count) { + tracer_relevant =3D ops_func_count; + tracer_irrelevant =3D ops_func_count; + } + + pr_info("registering:\n" + " relevant ops: %u\n" + " tracee: %ps\n" + " tracer: %ps\n" + " irrelevant ops: %u\n" + " tracee: %ps\n" + " tracer: %ps\n" + " saving registers: %s\n" + " assist recursion: %s\n" + " assist RCU: %s\n", + nr_ops_relevant, tracee_relevant, tracer_relevant, + nr_ops_irrelevant, tracee_irrelevant, tracer_irrelevant, + save_regs ? "YES" : "NO", + assist_recursion ? "YES" : "NO", + assist_rcu ? "YES" : "NO"); + + ops_relevant =3D ops_alloc_init(tracee_relevant, tracer_relevant, + flags, nr_ops_relevant); + ops_irrelevant =3D ops_alloc_init(tracee_irrelevant, tracer_irrelevant, + flags, nr_ops_irrelevant); + + start =3D ktime_get(); + for (unsigned int i =3D 0; i < nr_function_calls; i++) + tracee_relevant(); + end =3D ktime_get(); + + ops_check(ops_relevant, nr_ops_relevant, nr_function_calls); + ops_check(ops_irrelevant, nr_ops_irrelevant, 0); + + period =3D ktime_to_ns(ktime_sub(end, start)); + + pr_info("Attempted %u calls to %ps in %lluns (%lluns / call)\n", + nr_function_calls, tracee_relevant, + period, period / nr_function_calls); + + if (persist) + return 0; + + ops_destroy(ops_relevant, nr_ops_relevant); + ops_destroy(ops_irrelevant, nr_ops_irrelevant); + + /* + * The benchmark completed sucessfully, but there's no reason to keep + * the module around. Return an error do the user doesn't have to + * manually unload the module. + */ + return -EINVAL; +} +module_init(ftrace_ops_sample_init); + +static void __exit ftrace_ops_sample_exit(void) +{ + ops_destroy(ops_relevant, nr_ops_relevant); + ops_destroy(ops_irrelevant, nr_ops_irrelevant); +} +module_exit(ftrace_ops_sample_exit); + +MODULE_AUTHOR("Mark Rutland"); +MODULE_DESCRIPTION("Example of using custom ftrace_ops"); +MODULE_LICENSE("GPL"); --=20 2.30.2