Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932092AbZCQACH (ORCPT ); Mon, 16 Mar 2009 20:02:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753186AbZCQABx (ORCPT ); Mon, 16 Mar 2009 20:01:53 -0400 Received: from tomts43-srv.bellnexxia.net ([209.226.175.110]:62843 "EHLO tomts43-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752924AbZCQABv (ORCPT ); Mon, 16 Mar 2009 20:01:51 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ApQFALODvklMQW1W/2dsb2JhbACBTsURjhyDfwZh Date: Mon, 16 Mar 2009 20:01:38 -0400 From: Mathieu Desnoyers To: Jiaying Zhang Cc: linux-kernel@vger.kernel.org, Steven Rostedt , Michael Rubin , Martin Bligh , Michael Davidson , ltt-dev@lists.casi.polymtl.ca, Ingo Molnar Subject: Re: [RFC PATCH] Propose a new kernel tracing framework Message-ID: <20090317000138.GA19848@Krystal> References: <5df78e1d0902231610y615bcfb5hdbbc44736ecfce00@mail.gmail.com> <20090313170415.GE3354@Krystal> <5df78e1d0903161623s1d5d2a04h946668ac0c6a69f7@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <5df78e1d0903161623s1d5d2a04h946668ac0c6a69f7@mail.gmail.com> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 19:44:16 up 16 days, 20:10, 1 user, load average: 1.02, 0.55, 0.49 User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 56451 Lines: 1392 * Jiaying Zhang (jiayingz@google.com) wrote: > Hi Mathieu, > > First, I apologize that I did not forward you my original email. I assumed > that the email would be noticed by interested people when it was sent > to lkml. Now I see that is a mistake. > Hi Jiaying, Apologies accepted, no hard feeling :) I have just been surprised when I found out about the numbers you posted. > On Fri, Mar 13, 2009 at 10:04 AM, Mathieu Desnoyers > wrote: > > Hi Jiaying, > > > > I'm very interested to hear about the details of your test-case, because > > what you are talking about here, and the numbers that you get, are, at > > the very least, not representative of the current LTTng. Perharps you > > used a version right after the kernel summit and stopped following the > > improvements we have done since then ? I also wonder about the instrumentation > > set you enabled in your tests, and whether it's exactly the same in the ktrace > > and LTTng runs (especially system call tracing). Please note that following the > > Kernel Summit 2008, a more active development cycle began, and the time was not > > right for optimisation. But since then a lot of improvement has been done on > > this side. > > Sorry that I omitted a lot of details in my test description. I did use an old > version of LTTng in my tests. The LTTng version I used was the 0.21 lttng > patches for 2.6.27 kernel. I used 2.6.26 kernel in my tests, with the ported > lttng-2.6.27-rc6-0.21 patches. > > I enabled the same set of trace events in ktrace and LTTng runs. Here is > the list of enabled events: syscall entry/exit, irq entry/exit, trap > entry/exit, > kernel_sched_switch, kernel_process_fork, kernel_process_wait, > kernel_process_free, kernel_process_exit. > > We are glad to see the improvements coming from the LTTng community. > I haven't got time to sync with the latest LTTng code and re-run my tests. > I will let you know when I have such data available. > On my side, with flight recorder activated, same instrumentation you use, with LTTng 0.111 : arm-google script : #!/bin/sh DIR=/mnt/debugfs/ltt/markers for a in \ syscall_entry syscall_exit \ irq_entry irq_exit \ trap_entry trap_exit \ page_fault_entry page_fault_exit \ page_fault_nosem_entry page_fault_nosem_exit \ page_fault_get_user_entry page_fault_get_user_exit \ sched_schedule process_fork process_wait \ process_free process_exit; do echo 1 > ${DIR}/kernel/$a/enable done running tbench -t 200 8 Vanilla kernel : 2070 MB/sec Flight recorder : 1693 MB/sec Performance impact : 18.2 % Normal : 1620 MB/sec Performance impact : 21.7 % (8 lttd threads) So now we are comparing apples with apples :-) > > > > First I'd like to express my concern about the way you posted your > > numbers : > > > > 1 - You did not CC anyone from the LTTng project. > > 2 - You did not tell which LTTng version you used as a comparison basis. > > 3 - You did not look at the current state of code before posting your > > comparison. (as shows the comment in your patch header) > That is indeed my mistake. > > > 4 - You did not tell the instrumentation set that you enabled from LTTng. Is it > > the default instrumentation ? Did you also enable system call tracing > > with your tracer using set_kernel_trace_flag_all_tasks() ? If not, this > > makes a huge difference on the amount of information gathered. > Yes. We also enable syscall tracing via set_kernel_trace_flag_all_tasks(). > > > > > So let's have a close look at them. I'm re-doing the benchmarks based on > > the current LTTng version below. > > > >> Hello All, > >> > >> We have been working on building a kernel tracer for a production environment. > >> We first considered to use the existing markers code, but found it a bit > >> heavyweight. > > > > Have you looked at : > > > > 1 - The tracepoints currently in the kernel > > 2 - The _current_ version of markers in the LTTng tree ? > > I looked at the tracepoints currently in the kernel. It is great to see that > some trace instrumentation code is finally available in the mainline kernel. > But I still don't like an additional tracepoint layer on top of the > actual tracing > (ktrace or markers or ftrace) layer. That seems to add unnecessary overhead. > The markers code I referred to in my email is the current code in the mainline > kernel. I had a look at the LTTng markers code but still saw that va_list > argument is used in marker_probe_func. It sounds a nice improvement > if the LTTng markers avoids the use of va_arg whenever possible. > Yes, vs_args is only there as a commodity for slow paths. > > > >> So we developed a new kernel tracing prototype that shares > >> many similarities as markers but also includes several simplifications that > >> give us considerable performance benefits. For example, we pass the size of > >> trace event directly to the probe function instead of using va_arg as that > >> used in markers, which saves us the overhead of variable passing. > > > > The markers in the LTTng tree only use va_args for "debug-style" > > tracing. All the tracing fast paths are now done with custom probe > > functions which takes the arguments from the tracepoint and write them > > in the trace buffers directly in C. When the event payload size is already > > known statically, there is no dynamic computation cost at all : it's > > simply passed to the ltt-relay write function. > But this raises another concern that sub-system developers may need > to write a bunch of custom probe functions to avoid the argument parsing > overhead. Can you instead have a general probe function or macro that > does this work? > Well, considering the amount of care we have to take when we consider adding a tracepoint in the mainline kernel, I think it's even a *good* thing that someone has to stop and write a small callback to deal with the information he wants to export. I think debug-style tracing should be very, very quick and easy to add, but tracepoints meant to make it into the mainline does not share this requirement. > > > >> Also, we > >> associate a single probe function to each event, so we can directly call the > >> probe function when tracing is enabled. > > > > You seem to imply that being stuck with a single probe function is > > somehow superior to have tiny per-event callbacks which then call into a > > buffer write function ? Why ? > That is indeed my thinking, because we saw that some platforms are > very sensitive to function call overhead and we haven't seen use cases > where multi probe functions prove necessary. > Hrm, so your plan is to embed the tracing code at the caller site, or to keep one single function call ? > > > >> Our measurements show that our > >> current tracing prototype introduces much lower overhead compared with > >> lttng (we use lttng as a comparison because markers does not provide the > >> implementation to record trace data). > > > > Why LTTng version, kernel version, LTTng config and runtime options do > > you use ? > See above for LTTng and kernel versions. I was using the default LTTng > config options and 'normal' recorder mode. > > > > >> E.g., with dbench, lttng introduces > >> 20~80% overhead on our testing platforms while the overhead with our > >> kernel tracer is within 10%; with tbench, lttng usually adds more than 30% > >> overhead while the overhead added by our kernel tracer is usually within > >> 15%; with kernbench (time to compile a Linux kernel), the overhead > >> added by lttng is around 4%~18% while the overhead added by our > >> kernel tracer is within 2.5%. > >> > > > > I'm re-running the dbench and tbench tests : > > > > With LTTng 0.106, kernel 2.6.29-rc7 > > 8-cores Intel(R) Xeon(R) CPU E5405 @ 2.00GHz, 16GB ram > > > > Arming all the default LTTng instrumentation (168 tracepoints), > > Tracing in flight recorder mode, including system call entry/exit > > tracing and block I/O tracing (blktrace instrumentation), I get : > > > > Test / config | Vanilla kernel | LTTng 0.106 | slowdown > > dbench 8 -t 200 | 1361 MB/s | 1193 MB/s | 12.3 % > > > > As an example of the effect of custom probe vs va_args based probes, > > let's take the tbench example > > > > | Vanilla | LTTng 0.106 | slowdown > > tbench 8 -t 200 | 2074 MB/s | 997 MB/s | 52 % > > > > The LTTng trace statistics shows the top high event rate events : > > > > Some are usual (therefore lttng already implements custom probes for them) : > > > > 42004 sched_try_wakeup > > 79754 timer_set > > 83973 sched_schedule > > 84317 softirq_exit > > 84318 softirq_entry > > 95370 page_free > > 95412 page_alloc > > 267247 syscall_entry > > 267247 syscall_exit > > > > Some are more tbench workload-specific : > > > > 16915 socket_sendmsg > > 18911 napi_complete > > 18911 napi_schedule > > 18912 dev_receive > > 18914 dev_xmit > > 18920 napi_poll > > 33831 socket_recvmsg > > 59860 read > > > > > > So let's see what happens if I implement those as custom probes and do a bit of > > tuning in the tracer hot path : > Could you give more details about the custom probe you used? They are available in the lttng tree on git.kernel.org in ltt/probes/*-trace.c. Their API is in include/linux/ltt-type-serialize.h > Do you need to write a custom probe for each tracepoint? > Yes. But it's not such a big deal. It looks a bit like Steve's TRACE_EVENT macro-fu, but written in a simple C callback : void probe_sched_switch(struct rq *rq, struct task_struct *prev, struct task_struct *next); DEFINE_MARKER_TP(kernel, sched_schedule, sched_switch, probe_sched_switch, "prev_pid %d next_pid %d prev_state #2d%ld"); notrace void probe_sched_switch(struct rq *rq, struct task_struct *prev, struct task_struct *next) { struct marker *marker; struct serialize_int_int_short data; data.f1 = prev->pid; data.f2 = next->pid; data.f3 = prev->state; marker = &GET_MARKER(kernel, sched_schedule); ltt_specialized_trace(marker, marker->single.probe_private, &data, serialize_sizeof(data), sizeof(int)); } Best regards, Mathieu > Jiaying > > > > > | Vanilla | LTTng 0.107 | slowdown > > Custom probes : > > tbench 8 -t 200 | 2074 MB/s | 1275 MB/s | 38.5 % > > > > With tracer hot path tuning (inline hot path, function calls for slow path, will > > be in 0.108) : > > tbench 8 -t 200 | 2074 MB/s | 1335 MB/s | 35.6 % > > > > kernbench : > > Average Optimal load -j 32 Run > > > > Vanilla 2.6.29-rc7 : > > Elapsed Time 48.238 (0.117346) > > > > With flight recorder tracing, default lttng instrumentation, lttng 0.108 : > > Elapsed Time 50.226 (0.0750333) > > > > Slowdown : 4.1 % > > > > So except the tbench workload on LTTng 0.106, which still had a 52% performance > > impact (brought it down to 35 % for the next LTTng release) due to > > specific workload and not having specialized probes implemented, the > > dbench impact is well below your results (12.3 % vs 20-80%) > > > > So given the huge result discrepancies between your tests and mine, could you > > give us more detail about your benchmarks ? Especially knowing the enabled > > instrumentation set, and the amount of MB/s generated by both ktrace and LTTng > > runs (to make sure we are comparing the same traffic) and the LTTng versions you > > are using as a comparison basis would be good. > > > > Thanks, > > > > Mathieu > > > > > >> The patch below is the current prototype we have implemented. It uses > >> Steve's unified trace buffer code with some small extensions to support > >> buffer mmap. The patch is probably still buggy, but we would like to get > >> some early feedback from the community. > >> > >> Signed-off-by: Jiaying Zhang > >> > >> Index: git-linux/init/Kconfig > >> =================================================================== > >> --- git-linux.orig/init/Kconfig 2009-02-19 14:58:37.000000000 -0800 > >> +++ git-linux/init/Kconfig 2009-02-19 15:50:15.000000000 -0800 > >> @@ -950,6 +950,15 @@ > >> Place an empty function call at each marker site. Can be > >> dynamically changed for a probe function. > >> > >> +config KTRACE > >> + bool "Enable ktrace support" > >> + select DEBUG_FS > >> + select TRACING > >> + select RING_BUFFER > >> + help > >> + Ktrace is a kernel tracing tool that allows you to trace > >> + kernel events by inserting trace points at proper places. > >> + > >> source "arch/Kconfig" > >> > >> endmenu # General setup > >> Index: git-linux/kernel/Makefile > >> =================================================================== > >> --- git-linux.orig/kernel/Makefile 2009-02-19 14:58:37.000000000 -0800 > >> +++ git-linux/kernel/Makefile 2009-02-19 14:58:39.000000000 -0800 > >> @@ -86,6 +86,7 @@ > >> obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o > >> obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o > >> obj-$(CONFIG_MARKERS) += marker.o > >> +obj-$(CONFIG_KTRACE) += ktrace.o > >> obj-$(CONFIG_TRACEPOINTS) += tracepoint.o > >> obj-$(CONFIG_LATENCYTOP) += latencytop.o > >> obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o > >> Index: git-linux/include/asm-generic/vmlinux.lds.h > >> =================================================================== > >> --- git-linux.orig/include/asm-generic/vmlinux.lds.h 2009-02-19 > >> 14:58:37.000000000 -0800 > >> +++ git-linux/include/asm-generic/vmlinux.lds.h 2009-02-19 > >> 14:58:39.000000000 -0800 > >> @@ -73,6 +73,9 @@ > >> MEM_KEEP(init.data) \ > >> MEM_KEEP(exit.data) \ > >> . = ALIGN(8); \ > >> + VMLINUX_SYMBOL(__start___ktraces) = .; \ > >> + *(__ktrace) \ > >> + VMLINUX_SYMBOL(__stop___ktraces) = .; \ > >> VMLINUX_SYMBOL(__start___markers) = .; \ > >> *(__markers) \ > >> VMLINUX_SYMBOL(__stop___markers) = .; \ > >> @@ -89,6 +92,7 @@ > >> VMLINUX_SYMBOL(__start_rodata) = .; \ > >> *(.rodata) *(.rodata.*) \ > >> *(__vermagic) /* Kernel version magic */ \ > >> + *(__ktrace_strings) /* Ktrace: strings */ \ > >> *(__markers_strings) /* Markers: strings */ \ > >> *(__tracepoints_strings)/* Tracepoints: strings */ \ > >> } \ > >> Index: git-linux/kernel/module.c > >> =================================================================== > >> --- git-linux.orig/kernel/module.c 2009-02-19 14:58:37.000000000 -0800 > >> +++ git-linux/kernel/module.c 2009-02-19 14:58:39.000000000 -0800 > >> @@ -50,6 +50,7 @@ > >> #include > >> #include > >> #include > >> +#include > >> #include > >> > >> #if 0 > >> @@ -2145,6 +2146,10 @@ > >> sizeof(*mod->tracepoints), > >> &mod->num_tracepoints); > >> #endif > >> +#ifdef CONFIG_KTRACE > >> + mod->ktrace = section_objs(hdr, sechdrs, secstrings, "__ktrace", > >> + sizeof(*mod->ktrace), &mod->num_ktrace); > >> +#endif > >> > >> #ifdef CONFIG_MODVERSIONS > >> if ((mod->num_syms && !mod->crcs) > >> Index: git-linux/include/linux/module.h > >> =================================================================== > >> --- git-linux.orig/include/linux/module.h 2009-02-19 > >> 14:58:37.000000000 -0800 > >> +++ git-linux/include/linux/module.h 2009-02-19 14:58:39.000000000 -0800 > >> @@ -44,6 +44,7 @@ > >> }; > >> > >> struct module; > >> +struct kernel_trace; > >> > >> struct module_attribute { > >> struct attribute attr; > >> @@ -347,6 +348,11 @@ > >> /* Reference counts */ > >> struct module_ref ref[NR_CPUS]; > >> #endif > >> +#ifdef CONFIG_KTRACE > >> + struct kernel_trace *ktrace; > >> + unsigned int num_ktrace; > >> +#endif > >> + > >> }; > >> #ifndef MODULE_ARCH_INIT > >> #define MODULE_ARCH_INIT {} > >> Index: git-linux/include/linux/ktrace.h > >> =================================================================== > >> --- /dev/null 1970-01-01 00:00:00.000000000 +0000 > >> +++ git-linux/include/linux/ktrace.h 2009-02-19 15:36:39.000000000 -0800 > >> @@ -0,0 +1,83 @@ > >> +#ifndef _LINUX_KTRACE_H > >> +#define _LINUX_KTRACE_H > >> + > >> +#include > >> + > >> +struct kernel_trace; > >> + > >> +typedef void ktrace_probe_func(struct kernel_trace *, void *, size_t); > >> + > >> +struct kernel_trace { > >> + const char *name; > >> + const char *format; /* format string describing variable list */ > >> + size_t *stroff; /* offsets of string variables */ > >> + /* 31 bit event_id is converted to 16 bit when entering to the buffer */ > >> + u32 enabled:1, event_id:31; > >> + ktrace_probe_func *func; /* probe function */ > >> + struct list_head list; /* list head linked to the hash table entry */ > >> +} __attribute__((aligned(8))); > >> + > >> +extern int ktrace_enabled; > >> + > >> +/* > >> + * Make sure the alignment of the structure in the __ktrace section will > >> + * not add unwanted padding between the beginning of the section and the > >> + * structure. Force alignment to the same alignment as the section start. > >> + */ > >> + > >> +#define DEFINE_KTRACE_STRUCT(name) \ > >> + struct __attribute__((packed)) ktrace_struct_##name > >> + > >> +#ifdef CONFIG_KTRACE > >> +/* > >> + * DO_TRACE is the macro that is called from each trace point. Each trace > >> + * point is associated with a static ktrace object that is located in a > >> + * special __ktrace section and is uniquely identified by the event name and > >> + * event format. Take a look at the files under include/trace for example > >> + * usage. Note that we call the trace probe function only if the global > >> + * tracing is enabled and the tracing for the associated event is enabled, > >> + * so we only introduce the overhead of a predicted condition judge when > >> + * tracing is disabled. > >> + */ > >> +#define DO_TRACE(name, format, args...) > >> \ > >> + do { \ > >> + static const char __kstrtab_##name[] \ > >> + __attribute__((section("__ktrace_strings"))) \ > >> + = #name "\0" format; \ > >> + static struct kernel_trace __ktrace_##name \ > >> + __attribute__((section("__ktrace"), aligned(8))) = \ > >> + { __kstrtab_##name, &__kstrtab_##name[sizeof(#name)], \ > >> + NULL, 0, 0, NULL, LIST_HEAD_INIT(__ktrace_##name.list) }; \ > >> + __ktrace_check_format(format, ## args); \ > >> + if (unlikely(ktrace_enabled) && \ > >> + unlikely(__ktrace_##name.enabled)) { \ > >> + struct ktrace_struct_##name karg = { args }; \ > >> + (*__ktrace_##name.func) \ > >> + (&__ktrace_##name, &karg, sizeof(karg)); \ > >> + } \ > >> + } while (0) > >> + > >> +#else /* !CONFIG_KTRACE */ > >> +#define DO_TRACE(name, format, args...) > >> +#endif > >> + > >> +/* To be used for string format validity checking with gcc */ > >> +static inline void __printf(1, 2) ___ktrace_check_format(const char *fmt, ...) > >> +{ > >> +} > >> + > >> +#define __ktrace_check_format(format, args...) \ > >> + do { \ > >> + if (0) \ > >> + ___ktrace_check_format(format, ## args); \ > >> + } while (0) > >> + > >> + > >> +/* get the trace buffer information */ > >> +#define KTRACE_BUF_GET_SIZE _IOR(0xF5, 0x00, __u32) > >> +#define KTRACE_BUF_GET_PRODUCED _IOR(0xF5, 0x01, __u32) > >> +#define KTRACE_BUF_GET_CONSUMED _IOR(0xF5, 0x02, __u32) > >> +#define KTRACE_BUF_PUT_PRODUCED _IOW(0xF5, 0x03, __u32) > >> +#define KTRACE_BUF_PUT_CONSUMED _IOW(0xF5, 0x04, __u32) > >> + > >> +#endif > >> Index: git-linux/kernel/ktrace.c > >> =================================================================== > >> --- /dev/null 1970-01-01 00:00:00.000000000 +0000 > >> +++ git-linux/kernel/ktrace.c 2009-02-19 15:45:20.000000000 -0800 > >> @@ -0,0 +1,872 @@ > >> +/* > >> + * kernel/ktrace.c > >> + * > >> + * Implementation of the kernel tracing for linux kernel 2.6. > >> + * > >> + * Copyright 2008- Google Inc. > >> + * Original Author: Jiaying Zhang > >> + */ > >> + > >> +#include > >> +#include > >> +#include > >> +#include > >> +#include > >> +#include > >> +#include > >> +#include > >> +#include > >> +#include > >> +#include > >> +#include > >> +#include > >> +#include > >> +#include > >> + > >> +static char *ktrace_version = "1.0.0"; > >> +int ktrace_enabled; > >> +EXPORT_SYMBOL(ktrace_enabled); > >> +static uint16_t ktrace_next_id; > >> + > >> +extern struct kernel_trace __start___ktraces[]; > >> +extern struct kernel_trace __stop___ktraces[]; > >> + > >> +static DEFINE_MUTEX(ktrace_mutex); > >> + > >> +/* ktrace hash table entry structure and variables */ > >> +struct ktrace_entry { > >> + struct hlist_node hlist; > >> + char *name; > >> + char *format; > >> + size_t *stroff; > >> + ktrace_probe_func *func; > >> + u32 enabled:1, event_id:31; > >> + struct list_head klist; /* list of loaded ktraces */ > >> +}; > >> + > >> +#define KTRACE_HASH_BITS 6 > >> +#define KTRACE_HASH_SIZE (1 << KTRACE_HASH_BITS) > >> +static struct hlist_head ktrace_table[KTRACE_HASH_SIZE]; > >> + > >> +/* debugfs directory variables */ > >> +static struct dentry *tracedir; > >> +static struct dentry *eventdir; > >> +typedef void tracecontrol_handle_func(struct file *, unsigned long, size_t *); > >> + > >> +/* ring buffer code */ > >> +static unsigned long trace_buf_size = 65536UL; > >> +struct ring_buffer *trace_buffer; > >> +static DECLARE_WAIT_QUEUE_HEAD(trace_wait); /* waitqueue for trace_data_poll */ > >> +static struct timer_list trace_timer; /* reader wake-up timer */ > >> +#define TRACEREAD_WAKEUP_INTERVAL 1000 /* time interval in jiffies */ > >> +static struct kref ktrace_kref; > >> + > >> +static void > >> +ring_buffer_probe(struct kernel_trace *kt, void *data, size_t event_size) > >> +{ > >> + struct ring_buffer_event *event; > >> + void *trace_event; > >> + unsigned long flag; > >> + > >> + event = ring_buffer_lock_reserve(trace_buffer, > >> + sizeof(uint16_t) + event_size, &flag); > >> + if (!event) > >> + return; > >> + trace_event = ring_buffer_event_data(event); > >> + *(uint16_t *) trace_event = (uint16_t) kt->event_id; > >> + memcpy(trace_event + sizeof(uint16_t), data, event_size); > >> + ring_buffer_unlock_commit(trace_buffer, event, flag); > >> +} > >> + > >> +/* special probe function for events that contain string arguments */ > >> +static void > >> +string_probe(struct kernel_trace *kt, void *data, size_t event_size) > >> +{ > >> + struct ring_buffer_event *event; > >> + void *trace_event, *p; > >> + unsigned long flag; > >> + size_t *offset, scanned; > >> + char *string; > >> + > >> + /* > >> + * Get the real length of the event, i.e., we use stroff array to > >> + * locate string variables in the passed-in trace data and use their > >> + * length to replace the size of the string pointers. > >> + */ > >> + for (offset = kt->stroff; *offset != -1; offset++) { > >> + string = *(char **) (data + *offset); > >> + event_size += strlen(string) + 1 - sizeof(char *); > >> + } > >> + event = ring_buffer_lock_reserve(trace_buffer, > >> + sizeof(uint16_t) + event_size, &flag); > >> + if (!event) > >> + return; > >> + trace_event = ring_buffer_event_data(event); > >> + *(uint16_t *) trace_event = (uint16_t) kt->event_id; > >> + p = trace_event + sizeof(uint16_t); > >> + /* > >> + * Copy the trace data into buffer. For string variables, we enter the > >> + * string into the buffer. Otherwise, the passed in data is copied. > >> + */ > >> + for (offset = kt->stroff, scanned = 0; *offset != -1; offset++) { > >> + memcpy(p, data + scanned, *offset - scanned); > >> + p += *offset - scanned; > >> + string = *(char **) (data + *offset); > >> + memcpy(p, string, strlen(string) + 1); > >> + p += strlen(string) + 1; > >> + scanned = *offset + sizeof(char *); > >> + } > >> + memcpy(p, data + scanned, > >> + trace_event + sizeof(uint16_t) + event_size - p); > >> + ring_buffer_unlock_commit(trace_buffer, event, flag); > >> +} > >> + > >> +/* timer function used to defer ring buffer reader waking */ > >> +static void wakeup_readers(unsigned long data) > >> +{ > >> + if (trace_buffer && !ring_buffer_empty(trace_buffer)) > >> + wake_up_interruptible(&trace_wait); > >> + mod_timer(&trace_timer, jiffies + TRACEREAD_WAKEUP_INTERVAL); > >> +} > >> + > >> +/* function for reading ktrace metadata info */ > >> +static void *tracing_info_start(struct seq_file *seq, loff_t *pos) > >> +{ > >> + seq_printf(seq, "version %s\n", ktrace_version); > >> + return (*pos >= KTRACE_HASH_SIZE) ? NULL : &ktrace_table[*pos]; > >> +} > >> + > >> +static void *tracing_info_next(struct seq_file *seq, void *v, loff_t *pos) > >> +{ > >> + ++*pos; > >> + return (*pos >= KTRACE_HASH_SIZE) ? NULL : &ktrace_table[*pos]; > >> +} > >> + > >> +static int tracing_info_show(struct seq_file *seq, void *v) > >> +{ > >> + struct hlist_head *head = v; > >> + struct hlist_node *node; > >> + struct ktrace_entry *entry; > >> + hlist_for_each_entry(entry, node, head, hlist) > >> + seq_printf(seq, "name '%s' format '%s' id %u %s\n", > >> + entry->name, entry->format, entry->event_id, > >> + entry->enabled ? "enabled" : "disabled"); > >> + return 0; > >> +} > >> + > >> +static void tracing_info_stop(struct seq_file *seq, void *v) > >> +{ > >> +} > >> + > >> +static const struct seq_operations tracing_info_seq_ops = { > >> + .start = tracing_info_start, > >> + .next = tracing_info_next, > >> + .show = tracing_info_show, > >> + .stop = tracing_info_stop, > >> +}; > >> + > >> +static int tracing_info_open(struct inode *inode, struct file *file) > >> +{ > >> + return seq_open(file, &tracing_info_seq_ops); > >> +} > >> + > >> +static const struct file_operations traceinfo_file_operations = { > >> + .open = tracing_info_open, > >> + .read = seq_read, > >> + .llseek = seq_lseek, > >> + .release = seq_release, > >> +}; > >> + > >> +/* > >> + * wrapper function used by debugfs write operation. > >> + * func: handling function that does real work > >> + */ > >> +static ssize_t trace_debugfs_write(struct file *filp, const char __user *ubuf, > >> + size_t cnt, loff_t *ppos, tracecontrol_handle_func *func) > >> +{ > >> + int ret; > >> + char buf[64]; > >> + unsigned long val; > >> + > >> + if (cnt >= sizeof(buf)) > >> + return -EINVAL; > >> + if (copy_from_user(&buf, ubuf, cnt)) > >> + return -EFAULT; > >> + buf[cnt] = 0; > >> + > >> + ret = strict_strtoul(buf, 10, &val); > >> + if (ret < 0) > >> + return ret; > >> + val = !!val; > >> + > >> + func(filp, val, &cnt); > >> + > >> + filp->f_pos += cnt; > >> + return cnt; > >> +} > >> + > >> +/* functions for reading/writing the global 'enabled' control file */ > >> +static ssize_t tracing_control_read(struct file *filp, char __user *ubuf, > >> + size_t cnt, loff_t *ppos) > >> +{ > >> + int ret; > >> + char buf[64]; > >> + ret = snprintf(buf, 64, "%u\n", ktrace_enabled); > >> + return simple_read_from_buffer(ubuf, cnt, ppos, buf, ret); > >> +} > >> + > >> +static void __tracing_control_write(struct file *filp, > >> + unsigned long val, size_t *cnt) > >> +{ > >> + if (val ^ ktrace_enabled) { > >> + if (val) { > >> + trace_timer.expires = > >> + jiffies + TRACEREAD_WAKEUP_INTERVAL; > >> + add_timer(&trace_timer); > >> + ktrace_enabled = 1; > >> + } else { > >> + ktrace_enabled = 0; > >> + del_timer_sync(&trace_timer); > >> + if (trace_buffer && !ring_buffer_empty(trace_buffer)) > >> + wake_up_interruptible(&trace_wait); > >> + } > >> + } > >> +} > >> + > >> +static ssize_t tracing_control_write(struct file *filp, const char > >> __user *ubuf, > >> + size_t cnt, loff_t *ppos) > >> +{ > >> + return trace_debugfs_write(filp, ubuf, cnt, ppos, > >> + __tracing_control_write); > >> +} > >> + > >> +static const struct file_operations tracecontrol_file_operations = { > >> + .read = tracing_control_read, > >> + .write = tracing_control_write, > >> +}; > >> + > >> +/* functions for reading/writing a trace event file */ > >> +static int update_ktrace(struct ktrace_entry *entry, > >> + ktrace_probe_func *func, int enabled) > >> +{ > >> + struct kernel_trace *iter; > >> + /* no need to update the list if the tracing is not initialized */ > >> + if (!tracedir) > >> + return 0; > >> + entry->enabled = enabled; > >> + entry->func = func; > >> + list_for_each_entry(iter, &entry->klist, list) { > >> + iter->stroff = entry->stroff; > >> + iter->func = func; > >> + iter->enabled = enabled; > >> + } > >> + return 0; > >> +} > >> + > >> +static int ktrace_probe_register(struct ktrace_entry *entry, > >> + ktrace_probe_func *probefunc) > >> +{ > >> + return update_ktrace(entry, probefunc, 1); > >> +} > >> + > >> +static int ktrace_probe_unregister(struct ktrace_entry *entry) > >> +{ > >> + return update_ktrace(entry, NULL, 0); > >> +} > >> + > >> +static int ktrace_control_open(struct inode *inode, struct file *filp) > >> +{ > >> + filp->private_data = inode->i_private; > >> + return 0; > >> +} > >> + > >> +static ssize_t ktrace_control_read(struct file *filp, char __user *ubuf, > >> + size_t cnt, loff_t *ppos) > >> +{ > >> + int ret; > >> + char buf[64]; > >> + struct ktrace_entry *entry = filp->private_data; > >> + > >> + ret = snprintf(buf, 64, "%u\n", entry->enabled); > >> + return simple_read_from_buffer(ubuf, cnt, ppos, buf, ret); > >> +} > >> + > >> +/* > >> + * Check whether the event contains string arguments. Return 0 if not; > >> + * otherwise record the offsets of the string arguments in the ktrace > >> + * structure according to the event format and return 1. > >> + * The offset info is later used to store the string arguments into > >> + * the trace buffer during trace probe. > >> + */ > >> +static int contain_string_arguments(struct ktrace_entry *entry) > >> +{ > >> + int count = 0; > >> + char *fmt; > >> + int qualifier; /* 'h', 'l', or 'L' for integer fields */ > >> + size_t offset = 0; > >> + > >> + for (fmt = strstr(entry->format, "%s"); fmt; fmt = strstr(++fmt, "%s")) > >> + count++; > >> + if (!count) > >> + return 0; > >> + entry->stroff = kmalloc(sizeof(size_t) * (count + 1), GFP_KERNEL); > >> + if (!entry->stroff) > >> + return -ENOMEM; > >> + > >> + for (fmt = entry->format, count = 0; *fmt ; ++fmt) { > >> + if (*fmt != '%') > >> + continue; > >> +repeat: > >> + ++fmt; > >> + switch (*fmt) { > >> + case '-': > >> + case '+': > >> + case ' ': > >> + case '#': > >> + case '0': > >> + ++fmt; > >> + goto repeat; > >> + } > >> + > >> + while (isdigit(*fmt)) > >> + fmt++; > >> + > >> + /* get the conversion qualifier */ > >> + qualifier = -1; > >> + if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L') { > >> + qualifier = *fmt; > >> + ++fmt; > >> + if (qualifier == 'l' && *fmt == 'l') { > >> + qualifier = 'L'; > >> + ++fmt; > >> + } > >> + } > >> + > >> + switch (*fmt) { > >> + case 'c': > >> + offset += sizeof(char); > >> + continue; > >> + case 's': > >> + entry->stroff[count] = offset; > >> + count++; > >> + offset += sizeof(char *); > >> + continue; > >> + case 'p': > >> + offset += sizeof(void *); > >> + continue; > >> + case 'd': > >> + case 'i': > >> + case 'o': > >> + case 'u': > >> + case 'x': > >> + case 'X': > >> + switch (qualifier) { > >> + case 'L': > >> + offset += sizeof(long long); > >> + break; > >> + case 'l': > >> + offset += sizeof(long); > >> + break; > >> + case 'h': > >> + offset += sizeof(short); > >> + break; > >> + default: > >> + offset += sizeof(int); > >> + break; > >> + } > >> + break; > >> + default: > >> + printk(KERN_WARNING "unknown format '%c'", *fmt); > >> + continue; > >> + } > >> + } > >> + entry->stroff[count] = -1; > >> + return 1; > >> +} > >> + > >> +static void __ktrace_control_write(struct file *filp, > >> + unsigned long val, size_t *cnt) > >> +{ > >> + struct ktrace_entry *entry = filp->private_data; > >> + int ret; > >> + > >> + mutex_lock(&ktrace_mutex); > >> + if (val ^ entry->enabled) { > >> + if (val) { > >> + ret = contain_string_arguments(entry); > >> + if (ret == 0) > >> + ktrace_probe_register(entry, ring_buffer_probe); > >> + else if (ret > 0) > >> + ktrace_probe_register(entry, string_probe); > >> + else > >> + *cnt = ret; > >> + } else > >> + ktrace_probe_unregister(entry); > >> + } > >> + mutex_unlock(&ktrace_mutex); > >> +} > >> + > >> +static ssize_t ktrace_control_write(struct file *filp, const char __user *ubuf, > >> + size_t cnt, loff_t *ppos) > >> +{ > >> + return trace_debugfs_write(filp, ubuf, cnt, ppos, > >> + __ktrace_control_write); > >> +} > >> + > >> +static const struct file_operations ktracecontrol_file_operations = { > >> + .open = ktrace_control_open, > >> + .read = ktrace_control_read, > >> + .write = ktrace_control_write, > >> +}; > >> + > >> +/* functions for adding/removing a trace event. Protected by mutex lock. > >> + * Called during initialization or after loading a module */ > >> +static struct ktrace_entry *add_ktrace(struct kernel_trace *ktrace) > >> +{ > >> + struct ktrace_entry *entry; > >> + size_t name_len = strlen(ktrace->name) + 1; > >> + u32 hash = jhash(ktrace->name, name_len-1, 0); > >> + struct hlist_head *head; > >> + struct hlist_node *node; > >> + struct dentry *dentry; > >> + > >> + if (!tracedir) > >> + return 0; > >> + head = &ktrace_table[hash & ((1 << KTRACE_HASH_BITS)-1)]; > >> + hlist_for_each_entry(entry, node, head, hlist) { > >> + if (!strcmp(ktrace->name, entry->name)) { > >> + if (strcmp(ktrace->format, entry->format)) { > >> + printk(KERN_WARNING "the format of tracepoint " > >> + "\'%s\' changes from \'%s\' to \'%s\'." > >> + "Dynamic changing of trace format is " > >> + "not supported yet!\n", > >> + ktrace->name, entry->format, > >> + ktrace->format); > >> + return ERR_PTR(-EINVAL); > >> + } > >> + ktrace->enabled = entry->enabled; > >> + ktrace->func = entry->func; > >> + ktrace->event_id = entry->event_id; > >> + if (list_empty(&entry->klist)) > >> + goto add_head; > >> + list_add_tail(&ktrace->list, &entry->klist); > >> + return entry; > >> + } > >> + } > >> + entry = kmalloc(sizeof(struct ktrace_entry), GFP_KERNEL); > >> + if (!entry) > >> + return ERR_PTR(-ENOMEM); > >> + entry->name = kmalloc(name_len, GFP_KERNEL); > >> + if (!entry->name) { > >> + kfree(entry); > >> + return ERR_PTR(-ENOMEM); > >> + } > >> + memcpy(entry->name, ktrace->name, name_len); > >> + if (ktrace->format) { > >> + size_t format_len = strlen(ktrace->format) + 1; > >> + entry->format = kmalloc(format_len, GFP_KERNEL); > >> + if (!entry->format) { > >> + kfree(entry->name); > >> + kfree(entry); > >> + return ERR_PTR(-ENOMEM); > >> + } > >> + memcpy(entry->format, ktrace->format, format_len); > >> + } else > >> + entry->format = NULL; > >> + entry->func = ktrace->func; > >> + entry->enabled = 0; > >> + ktrace->event_id = entry->event_id = ktrace_next_id++; > >> + entry->stroff = NULL; > >> + INIT_LIST_HEAD(&entry->klist); > >> + hlist_add_head(&entry->hlist, head); > >> +add_head: > >> + list_add(&ktrace->list, &entry->klist); > >> + dentry = debugfs_create_file(entry->name, 0660, eventdir, > >> + entry, &ktracecontrol_file_operations); > >> + if (!dentry) > >> + printk(KERN_WARNING "Couldn't create debugfs '%s' entry\n", > >> + entry->name); > >> + return entry; > >> +} > >> + > >> +static int remove_ktrace(struct kernel_trace *ktrace, int free) > >> +{ > >> + struct ktrace_entry *entry; > >> + size_t name_len = strlen(ktrace->name) + 1; > >> + u32 hash = jhash(ktrace->name, name_len-1, 0); > >> + struct hlist_head *head; > >> + struct hlist_node *node, *temp; > >> + struct dentry *dentry; > >> + > >> + if (!tracedir) > >> + return 0; > >> + list_del(&ktrace->list); > >> + head = &ktrace_table[hash & ((1 << KTRACE_HASH_BITS)-1)]; > >> + hlist_for_each_entry_safe(entry, node, temp, head, hlist) > >> + if (!strcmp(ktrace->name, entry->name)) { > >> + if (list_empty(&entry->klist)) { > >> + dentry = lookup_one_len(entry->name, > >> + eventdir, strlen(entry->name)); > >> + if (dentry && !IS_ERR(dentry)) { > >> + debugfs_remove(dentry); > >> + dput(dentry); > >> + } > >> + entry->enabled = 0; > >> + if (free) { > >> + hlist_del(&entry->hlist); > >> + kfree(entry->name); > >> + kfree(entry->format); > >> + kfree(entry->stroff); > >> + kfree(entry); > >> + } > >> + } > >> + return 0; > >> + } > >> + return -1; > >> +} > >> + > >> +/* Add/remove tracepoints contained in a module to the ktrace hash table. > >> + * Called at the end of module load/unload. */ > >> +static int ktrace_module_notify(struct notifier_block *self, > >> + unsigned long val, void *data) > >> +{ > >> +#ifdef CONFIG_MODULES > >> + struct kernel_trace *iter; > >> + struct module *mod = data; > >> + > >> + if (val != MODULE_STATE_COMING && val != MODULE_STATE_GOING) > >> + return 0; > >> + mutex_lock(&ktrace_mutex); > >> + for (iter = mod->ktrace; iter < mod->ktrace + mod->num_ktrace; iter++) > >> + if (val == MODULE_STATE_COMING) > >> + add_ktrace(iter); > >> + else > >> + remove_ktrace(iter, 0); > >> + mutex_unlock(&ktrace_mutex); > >> +#endif > >> + return 0; > >> +} > >> + > >> +static struct notifier_block ktrace_module_nb = { > >> + .notifier_call = ktrace_module_notify, > >> +}; > >> + > >> +/* functions for user-space programs to read data from tracing buffer */ > >> +static int trace_data_open(struct inode *inode, struct file *filp) > >> +{ > >> + filp->private_data = inode->i_private; > >> + kref_get(&ktrace_kref); > >> + return 0; > >> +} > >> + > >> +static void release_trace_buffer(struct kref *kref) > >> +{ > >> + ring_buffer_free(trace_buffer); > >> + trace_buffer = NULL; > >> +} > >> + > >> +static int trace_data_release(struct inode *inode, struct file *filp) > >> +{ > >> + kref_put(&ktrace_kref, release_trace_buffer); > >> + return 0; > >> +} > >> + > >> +static unsigned int trace_data_poll(struct file *filp, poll_table *poll_table) > >> +{ > >> + struct ring_buffer_per_cpu *cpu_buffer = filp->private_data; > >> + if (filp->f_mode & FMODE_READ) { > >> + if (!ring_buffer_per_cpu_empty(cpu_buffer)) > >> + return POLLIN | POLLRDNORM; > >> + poll_wait(filp, &trace_wait, poll_table); > >> + if (!ring_buffer_per_cpu_empty(cpu_buffer)) > >> + return POLLIN | POLLRDNORM; > >> + } > >> + return 0; > >> +} > >> + > >> +static int trace_buf_fault(struct vm_area_struct *vma, struct vm_fault *vmf) > >> +{ > >> + struct ring_buffer_per_cpu *cpu_buffer = vma->vm_private_data; > >> + pgoff_t pgoff = vmf->pgoff; > >> + struct page *page; > >> + > >> + if (!trace_buffer) > >> + return VM_FAULT_OOM; > >> + page = ring_buffer_get_page(cpu_buffer, pgoff); > >> + if (page == NULL) > >> + return VM_FAULT_SIGBUS; > >> + get_page(page); > >> + vmf->page = page; > >> + return 0; > >> +} > >> + > >> +static struct vm_operations_struct trace_data_mmap_ops = { > >> + .fault = trace_buf_fault, > >> +}; > >> + > >> +static int trace_data_mmap(struct file *filp, struct vm_area_struct *vma) > >> +{ > >> + struct ring_buffer_per_cpu *cpu_buffer = filp->private_data; > >> + > >> + vma->vm_ops = &trace_data_mmap_ops; > >> + vma->vm_flags |= VM_DONTEXPAND; > >> + vma->vm_private_data = cpu_buffer; > >> + return 0; > >> +} > >> + > >> +static int trace_data_ioctl(struct inode *inode, struct file *filp, > >> + unsigned int cmd, unsigned long arg) > >> +{ > >> + u32 __user *argp = (u32 __user *)arg; > >> + struct ring_buffer_per_cpu *cpu_buffer = filp->private_data; > >> + > >> + if (!trace_buffer || !tracedir) > >> + return -EINVAL; > >> + switch (cmd) { > >> + case KTRACE_BUF_GET_SIZE: > >> + { > >> + unsigned long bufsize; > >> + bufsize = ring_buffer_size(trace_buffer); > >> + return put_user((u32)bufsize, argp); > >> + } > >> + case KTRACE_BUF_GET_PRODUCED: > >> + return put_user(ring_buffer_get_produced(cpu_buffer), argp); > >> + case KTRACE_BUF_GET_CONSUMED: > >> + return put_user(ring_buffer_get_consumed(cpu_buffer), argp); > >> + case KTRACE_BUF_PUT_CONSUMED: > >> + { > >> + u32 consumed, consumed_old; > >> + int ret; > >> + > >> + ret = get_user(consumed, argp); > >> + if (ret) { > >> + printk(KERN_WARNING > >> + "error getting consumed value: %d\n", ret); > >> + return ret; > >> + } > >> + consumed_old = ring_buffer_get_consumed(cpu_buffer); > >> + if (consumed == consumed_old) > >> + return 0; > >> + ring_buffer_advance_reader(cpu_buffer, consumed - consumed_old); > >> + return 0; > >> + } > >> + default: > >> + return -ENOIOCTLCMD; > >> + } > >> + return 0; > >> +} > >> + > >> +static const struct file_operations tracedata_file_operations = { > >> + .open = trace_data_open, > >> + .poll = trace_data_poll, > >> + .mmap = trace_data_mmap, > >> + .ioctl = trace_data_ioctl, > >> + .release = trace_data_release, > >> +}; > >> + > >> +/* function to report the number of lost events due to buffer overflow */ > >> +static ssize_t trace_overflow_read(struct file *filp, char __user *ubuf, > >> + size_t cnt, loff_t *ppos) > >> +{ > >> + int ret; > >> + char buf[64]; > >> + ret = snprintf(buf, 64, "%lu\n", ring_buffer_overruns(trace_buffer)); > >> + return simple_read_from_buffer(ubuf, cnt, ppos, buf, ret); > >> +} > >> + > >> +static const struct file_operations traceoverflow_file_operations = { > >> + .read = trace_overflow_read, > >> +}; > >> + > >> +/* function to re-initialize trace buffer */ > >> +static void __trace_buffer_reset(struct file *filp, > >> + unsigned long val, size_t *cnt) > >> +{ > >> + if (val && trace_buffer) > >> + ring_buffer_reset(trace_buffer); > >> +} > >> + > >> +static ssize_t trace_buffer_reset(struct file *filp, const char __user *ubuf, > >> + size_t cnt, loff_t *ppos) > >> +{ > >> + return trace_debugfs_write(filp, ubuf, cnt, ppos, > >> + __trace_buffer_reset); > >> +} > >> + > >> +static const struct file_operations tracereset_file_operations = { > >> + .write = trace_buffer_reset, > >> +}; > >> + > >> +/* > >> + * We use debugfs for kernel-user communication. All of the control/info > >> + * files are under debugfs/ktrace directory. > >> + */ > >> +static int create_debugfs(void) > >> +{ > >> + struct dentry *entry, *bufdir; > >> + struct ring_buffer_per_cpu *cpu_buffer; > >> + char *tmpname; > >> + int cpu; > >> + > >> + tracedir = debugfs_create_dir("ktrace", NULL); > >> + if (!tracedir) { > >> + printk(KERN_WARNING "Couldn't create debugfs directory\n"); > >> + return -ENOMEM; > >> + } > >> + > >> + /* 'buffers' is the directory that holds trace buffer debugfs files */ > >> + bufdir = debugfs_create_dir("buffers", tracedir); > >> + if (!bufdir) { > >> + printk(KERN_WARNING "Couldn't create 'buffers' directory\n"); > >> + return -ENOMEM; > >> + } > >> + > >> + tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL); > >> + if (!tmpname) > >> + return -ENOMEM; > >> + /* create a debugfs file for each cpu buffer */ > >> + for_each_possible_cpu(cpu) { > >> + snprintf(tmpname, NAME_MAX, "%s%d", "cpu", cpu); > >> + cpu_buffer = ring_buffer_cpu(trace_buffer, cpu); > >> + entry = debugfs_create_file(tmpname, 0440, bufdir, cpu_buffer, > >> + &tracedata_file_operations); > >> + if (!entry) { > >> + printk(KERN_WARNING > >> + "Couldn't create debugfs \'%s\' entry\n", > >> + tmpname); > >> + return -ENOMEM; > >> + } > >> + } > >> + kfree(tmpname); > >> + > >> + /* the control file for users to enable/disable global tracing. */ > >> + entry = debugfs_create_file("enabled", 0664, tracedir, NULL, > >> + &tracecontrol_file_operations); > >> + if (!entry) { > >> + printk(KERN_WARNING > >> + "Couldn't create debugfs 'enabled' entry\n"); > >> + return -ENOMEM; > >> + } > >> + > >> + /* > >> + * the debugfs file that displays the name, format etc. of every > >> + * supported trace event. The file is to be used by the user-space > >> + * trace parser to analyze the collected trace data. > >> + */ > >> + entry = debugfs_create_file("info", 0444, tracedir, NULL, > >> + &traceinfo_file_operations); > >> + if (!entry) { > >> + printk(KERN_WARNING "Couldn't create debugfs 'info' entry\n"); > >> + return -ENOMEM; > >> + } > >> + > >> + /* > >> + * the debugfs file that reports the number of events > >> + * lost due to buffer overflow > >> + */ > >> + entry = debugfs_create_file("overflow", 0444, tracedir, NULL, > >> + &traceoverflow_file_operations); > >> + if (!entry) { > >> + printk(KERN_WARNING > >> + "Couldn't create debugfs 'overflow' entry\n"); > >> + return -ENOMEM; > >> + } > >> + > >> + /* the debugfs file that resets trace buffer upon write */ > >> + entry = debugfs_create_file("reset", 0220, tracedir, NULL, > >> + &tracereset_file_operations); > >> + if (!entry) { > >> + printk(KERN_WARNING "Couldn't create debugfs 'reset' entry\n"); > >> + return -ENOMEM; > >> + } > >> + > >> + /* create the directory that holds the control files for every event */ > >> + eventdir = debugfs_create_dir("events", tracedir); > >> + if (!eventdir) { > >> + printk(KERN_WARNING "Couldn't create 'events' directory\n"); > >> + return -ENOMEM; > >> + } > >> + return 0; > >> +} > >> + > >> +static void remove_debugfs_file(struct dentry *dir, char *name) > >> +{ > >> + struct dentry *dentry; > >> + dentry = lookup_one_len(name, dir, strlen(name)); > >> + if (dentry && !IS_ERR(dentry)) { > >> + debugfs_remove(dentry); > >> + dput(dentry); > >> + } > >> +} > >> + > >> +static int remove_debugfs(void) > >> +{ > >> + struct dentry *bufdir; > >> + char *tmpname; > >> + int cpu; > >> + > >> + bufdir = lookup_one_len("buffers", tracedir, strlen("buffers")); > >> + if (!bufdir || IS_ERR(bufdir)) > >> + return -EIO; > >> + tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL); > >> + if (!tmpname) > >> + return -ENOMEM; > >> + for_each_possible_cpu(cpu) { > >> + snprintf(tmpname, NAME_MAX, "%s%d", "cpu", cpu); > >> + remove_debugfs_file(bufdir, tmpname); > >> + } > >> + kfree(tmpname); > >> + debugfs_remove(bufdir); > >> + > >> + remove_debugfs_file(tracedir, "enabled"); > >> + remove_debugfs_file(tracedir, "info"); > >> + debugfs_remove(eventdir); > >> + debugfs_remove(tracedir); > >> + return 0; > >> +} > >> + > >> +static int __init init_ktrace(void) > >> +{ > >> + struct kernel_trace *iter; > >> + int i, err; > >> + > >> + ktrace_next_id = 0; > >> + kref_set(&ktrace_kref, 1); > >> + trace_buffer = ring_buffer_alloc(trace_buf_size, RB_FL_OVERWRITE); > >> + if (trace_buffer == NULL) > >> + return -ENOMEM; > >> + setup_timer(&trace_timer, wakeup_readers, 0); > >> + for (i = 0; i < KTRACE_HASH_SIZE; i++) > >> + INIT_HLIST_HEAD(&ktrace_table[i]); > >> + > >> + mutex_lock(&ktrace_mutex); > >> + err = create_debugfs(); > >> + if (err != 0) > >> + goto out; > >> + for (iter = __start___ktraces; iter < __stop___ktraces; iter++) > >> + add_ktrace(iter); > >> + err = register_module_notifier(&ktrace_module_nb); > >> +out: > >> + mutex_unlock(&ktrace_mutex); > >> + return err; > >> +} > >> +module_init(init_ktrace); > >> + > >> +static void __exit exit_ktrace(void) > >> +{ > >> + struct kernel_trace *iter; > >> + > >> + if (ktrace_enabled) { > >> + ktrace_enabled = 0; > >> + del_timer_sync(&trace_timer); > >> + } > >> + mutex_lock(&ktrace_mutex); > >> + for (iter = __start___ktraces; iter < __stop___ktraces; iter++) > >> + remove_ktrace(iter, 1); > >> + unregister_module_notifier(&ktrace_module_nb); > >> + remove_debugfs(); > >> + mutex_unlock(&ktrace_mutex); > >> + > >> + kref_put(&ktrace_kref, release_trace_buffer); > >> +} > > > > -- > > Mathieu Desnoyers > > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 > > -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/