| Message ID | 1479715043-6534-2-git-send-email-zhang.chunyan@linaro.org |
|---|---|
| State | New |
| Headers | show |
On Mon, 21 Nov 2016 15:57:18 +0800 Chunyan Zhang <zhang.chunyan@linaro.org> wrote: > Currently Function traces can be only exported to ring buffer, this > patch added trace_export concept which can process traces and export > them to a registered destination as an addition to the current only > one output of Ftrace - i.e. ring buffer. > > In this way, if we want Function traces to be sent to other destination > rather than ring buffer only, we just need to register a new trace_export > and implement its own .write() function for writing traces to storage. > > With this patch, only Function trace (trace type is TRACE_FN) > is supported. > > Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org> > --- > include/linux/trace.h | 28 +++++++++++ > kernel/trace/trace.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++++- > 2 files changed, 156 insertions(+), 1 deletion(-) > create mode 100644 include/linux/trace.h > > diff --git a/include/linux/trace.h b/include/linux/trace.h > new file mode 100644 > index 0000000..9330a58 > --- /dev/null > +++ b/include/linux/trace.h > @@ -0,0 +1,28 @@ > +#ifndef _LINUX_TRACE_H > +#define _LINUX_TRACE_H > + > +#ifdef CONFIG_TRACING > +/* > + * The trace export - an export of Ftrace output. The trace_export > + * can process traces and export them to a registered destination as > + * an addition to the current only output of Ftrace - i.e. ring buffer. > + * > + * If you want traces to be sent to some other place rather than ring > + * buffer only, just need to register a new trace_export and implement > + * its own .write() function for writing traces to the storage. > + * > + * next - pointer to the next trace_export > + * write - copy traces which have been delt with ->commit() to > + * the destination > + */ > +struct trace_export { > + struct trace_export __rcu *next; > + void (*write)(const void *, unsigned int); > +}; > + > +int register_ftrace_export(struct trace_export *export); > +int unregister_ftrace_export(struct trace_export *export); > + > +#endif /* CONFIG_TRACING */ > + > +#endif /* _LINUX_TRACE_H */ > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 8696ce6..038291d 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -40,6 +40,7 @@ > #include <linux/poll.h> > #include <linux/nmi.h> > #include <linux/fs.h> > +#include <linux/trace.h> > #include <linux/sched/rt.h> > > #include "trace.h" > @@ -2128,6 +2129,129 @@ void trace_buffer_unlock_commit_regs(struct trace_array *tr, > ftrace_trace_userstack(buffer, flags, pc); > } > > +static void > +trace_process_export(struct trace_export *export, > + struct ring_buffer_event *event) > +{ > + struct trace_entry *entry; > + unsigned int size = 0; > + > + entry = ring_buffer_event_data(event); > + size = ring_buffer_event_length(event); > + export->write(entry, size); > +} > + > +static DEFINE_MUTEX(ftrace_export_lock); > + > +static struct trace_export __rcu *ftrace_exports_list __read_mostly; > + > +static DEFINE_STATIC_KEY_FALSE(ftrace_exports_enabled); > + > +static inline void ftrace_exports_enable(void) > +{ > + static_branch_enable(&ftrace_exports_enabled); > +} > + > +static inline void ftrace_exports_disable(void) > +{ > + static_branch_disable(&ftrace_exports_enabled); > +} > + > +void ftrace_exports(struct ring_buffer_event *event) I'm currently testing the patches, but is there a reason that ftrace_exports() is not static? -- Steve > +{ > + struct trace_export *export; > + > + preempt_disable_notrace(); > + > + export = rcu_dereference_raw_notrace(ftrace_exports_list); > + while (export) { > + trace_process_export(export, event); > + export = rcu_dereference_raw_notrace(export->next); > + } > + > + preempt_enable_notrace(); > +} > + > +static inline void > +add_trace_export(struct trace_export **list, struct trace_export *export) > +{ > + rcu_assign_pointer(export->next, *list); > + /* > + * We are entering export into the list but another > + * CPU might be walking that list. We need to make sure > + * the export->next pointer is valid before another CPU sees > + * the export pointer included into the list. > + */ > + rcu_assign_pointer(*list, export); > +} > + > +static inline int > +rm_trace_export(struct trace_export **list, struct trace_export *export) > +{ > + struct trace_export **p; > + > + for (p = list; *p != NULL; p = &(*p)->next) > + if (*p == export) > + break; > + > + if (*p != export) > + return -1; > + > + rcu_assign_pointer(*p, (*p)->next); > + > + return 0; > +} > + > +static inline void > +add_ftrace_export(struct trace_export **list, struct trace_export *export) > +{ > + if (*list == NULL) > + ftrace_exports_enable(); > + > + add_trace_export(list, export); > +} > + > +static inline int > +rm_ftrace_export(struct trace_export **list, struct trace_export *export) > +{ > + int ret; > + > + ret = rm_trace_export(list, export); > + if (*list == NULL) > + ftrace_exports_disable(); > + > + return ret; > +} > + > +int register_ftrace_export(struct trace_export *export) > +{ > + if (WARN_ON_ONCE(!export->write)) > + return -1; > + > + mutex_lock(&ftrace_export_lock); > + > + add_ftrace_export(&ftrace_exports_list, export); > + > + mutex_unlock(&ftrace_export_lock); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(register_ftrace_export); > + > +int unregister_ftrace_export(struct trace_export *export) > +{ > + int ret; > + > + mutex_lock(&ftrace_export_lock); > + > + ret = rm_ftrace_export(&ftrace_exports_list, export); > + > + mutex_unlock(&ftrace_export_lock); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(unregister_ftrace_export); > + > void > trace_function(struct trace_array *tr, > unsigned long ip, unsigned long parent_ip, unsigned long flags, > @@ -2146,8 +2270,11 @@ trace_function(struct trace_array *tr, > entry->ip = ip; > entry->parent_ip = parent_ip; > > - if (!call_filter_check_discard(call, entry, buffer, event)) > + if (!call_filter_check_discard(call, entry, buffer, event)) { > + if (static_branch_unlikely(&ftrace_exports_enabled)) > + ftrace_exports(event); > __buffer_unlock_commit(buffer, event); > + } > } > > #ifdef CONFIG_STACKTRACE
On 23 November 2016 at 06:39, Steven Rostedt <rostedt@goodmis.org> wrote: > On Mon, 21 Nov 2016 15:57:18 +0800 > Chunyan Zhang <zhang.chunyan@linaro.org> wrote: > >> Currently Function traces can be only exported to ring buffer, this >> patch added trace_export concept which can process traces and export >> them to a registered destination as an addition to the current only >> one output of Ftrace - i.e. ring buffer. >> >> In this way, if we want Function traces to be sent to other destination >> rather than ring buffer only, we just need to register a new trace_export >> and implement its own .write() function for writing traces to storage. >> >> With this patch, only Function trace (trace type is TRACE_FN) >> is supported. >> >> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org> >> --- >> include/linux/trace.h | 28 +++++++++++ >> kernel/trace/trace.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++++- >> 2 files changed, 156 insertions(+), 1 deletion(-) >> create mode 100644 include/linux/trace.h >> >> diff --git a/include/linux/trace.h b/include/linux/trace.h >> new file mode 100644 >> index 0000000..9330a58 >> --- /dev/null >> +++ b/include/linux/trace.h >> @@ -0,0 +1,28 @@ >> +#ifndef _LINUX_TRACE_H >> +#define _LINUX_TRACE_H >> + >> +#ifdef CONFIG_TRACING >> +/* >> + * The trace export - an export of Ftrace output. The trace_export >> + * can process traces and export them to a registered destination as >> + * an addition to the current only output of Ftrace - i.e. ring buffer. >> + * >> + * If you want traces to be sent to some other place rather than ring >> + * buffer only, just need to register a new trace_export and implement >> + * its own .write() function for writing traces to the storage. >> + * >> + * next - pointer to the next trace_export >> + * write - copy traces which have been delt with ->commit() to >> + * the destination >> + */ >> +struct trace_export { >> + struct trace_export __rcu *next; >> + void (*write)(const void *, unsigned int); >> +}; >> + >> +int register_ftrace_export(struct trace_export *export); >> +int unregister_ftrace_export(struct trace_export *export); >> + >> +#endif /* CONFIG_TRACING */ >> + >> +#endif /* _LINUX_TRACE_H */ >> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c >> index 8696ce6..038291d 100644 >> --- a/kernel/trace/trace.c >> +++ b/kernel/trace/trace.c >> @@ -40,6 +40,7 @@ >> #include <linux/poll.h> >> #include <linux/nmi.h> >> #include <linux/fs.h> >> +#include <linux/trace.h> >> #include <linux/sched/rt.h> >> >> #include "trace.h" >> @@ -2128,6 +2129,129 @@ void trace_buffer_unlock_commit_regs(struct trace_array *tr, >> ftrace_trace_userstack(buffer, flags, pc); >> } >> >> +static void >> +trace_process_export(struct trace_export *export, >> + struct ring_buffer_event *event) >> +{ >> + struct trace_entry *entry; >> + unsigned int size = 0; >> + >> + entry = ring_buffer_event_data(event); >> + size = ring_buffer_event_length(event); >> + export->write(entry, size); >> +} >> + >> +static DEFINE_MUTEX(ftrace_export_lock); >> + >> +static struct trace_export __rcu *ftrace_exports_list __read_mostly; >> + >> +static DEFINE_STATIC_KEY_FALSE(ftrace_exports_enabled); >> + >> +static inline void ftrace_exports_enable(void) >> +{ >> + static_branch_enable(&ftrace_exports_enabled); >> +} >> + >> +static inline void ftrace_exports_disable(void) >> +{ >> + static_branch_disable(&ftrace_exports_enabled); >> +} >> + >> +void ftrace_exports(struct ring_buffer_event *event) > > I'm currently testing the patches, but is there a reason that > ftrace_exports() is not static? At present ftrace_exports() is only used by function trace though, but I hope it can be used by other traces when it needed. So I didn't mark it with static, but if you think it should better be static for the time being, I can revise that. Thanks, Chunyan > > -- Steve > >> +{ >> + struct trace_export *export; >> + >> + preempt_disable_notrace(); >> + >> + export = rcu_dereference_raw_notrace(ftrace_exports_list); >> + while (export) { >> + trace_process_export(export, event); >> + export = rcu_dereference_raw_notrace(export->next); >> + } >> + >> + preempt_enable_notrace(); >> +} >> + >> +static inline void >> +add_trace_export(struct trace_export **list, struct trace_export *export) >> +{ >> + rcu_assign_pointer(export->next, *list); >> + /* >> + * We are entering export into the list but another >> + * CPU might be walking that list. We need to make sure >> + * the export->next pointer is valid before another CPU sees >> + * the export pointer included into the list. >> + */ >> + rcu_assign_pointer(*list, export); >> +} >> + >> +static inline int >> +rm_trace_export(struct trace_export **list, struct trace_export *export) >> +{ >> + struct trace_export **p; >> + >> + for (p = list; *p != NULL; p = &(*p)->next) >> + if (*p == export) >> + break; >> + >> + if (*p != export) >> + return -1; >> + >> + rcu_assign_pointer(*p, (*p)->next); >> + >> + return 0; >> +} >> + >> +static inline void >> +add_ftrace_export(struct trace_export **list, struct trace_export *export) >> +{ >> + if (*list == NULL) >> + ftrace_exports_enable(); >> + >> + add_trace_export(list, export); >> +} >> + >> +static inline int >> +rm_ftrace_export(struct trace_export **list, struct trace_export *export) >> +{ >> + int ret; >> + >> + ret = rm_trace_export(list, export); >> + if (*list == NULL) >> + ftrace_exports_disable(); >> + >> + return ret; >> +} >> + >> +int register_ftrace_export(struct trace_export *export) >> +{ >> + if (WARN_ON_ONCE(!export->write)) >> + return -1; >> + >> + mutex_lock(&ftrace_export_lock); >> + >> + add_ftrace_export(&ftrace_exports_list, export); >> + >> + mutex_unlock(&ftrace_export_lock); >> + >> + return 0; >> +} >> +EXPORT_SYMBOL_GPL(register_ftrace_export); >> + >> +int unregister_ftrace_export(struct trace_export *export) >> +{ >> + int ret; >> + >> + mutex_lock(&ftrace_export_lock); >> + >> + ret = rm_ftrace_export(&ftrace_exports_list, export); >> + >> + mutex_unlock(&ftrace_export_lock); >> + >> + return ret; >> +} >> +EXPORT_SYMBOL_GPL(unregister_ftrace_export); >> + >> void >> trace_function(struct trace_array *tr, >> unsigned long ip, unsigned long parent_ip, unsigned long flags, >> @@ -2146,8 +2270,11 @@ trace_function(struct trace_array *tr, >> entry->ip = ip; >> entry->parent_ip = parent_ip; >> >> - if (!call_filter_check_discard(call, entry, buffer, event)) >> + if (!call_filter_check_discard(call, entry, buffer, event)) { >> + if (static_branch_unlikely(&ftrace_exports_enabled)) >> + ftrace_exports(event); >> __buffer_unlock_commit(buffer, event); >> + } >> } >> >> #ifdef CONFIG_STACKTRACE >
diff --git a/include/linux/trace.h b/include/linux/trace.h new file mode 100644 index 0000000..9330a58 --- /dev/null +++ b/include/linux/trace.h @@ -0,0 +1,28 @@ +#ifndef _LINUX_TRACE_H +#define _LINUX_TRACE_H + +#ifdef CONFIG_TRACING +/* + * The trace export - an export of Ftrace output. The trace_export + * can process traces and export them to a registered destination as + * an addition to the current only output of Ftrace - i.e. ring buffer. + * + * If you want traces to be sent to some other place rather than ring + * buffer only, just need to register a new trace_export and implement + * its own .write() function for writing traces to the storage. + * + * next - pointer to the next trace_export + * write - copy traces which have been delt with ->commit() to + * the destination + */ +struct trace_export { + struct trace_export __rcu *next; + void (*write)(const void *, unsigned int); +}; + +int register_ftrace_export(struct trace_export *export); +int unregister_ftrace_export(struct trace_export *export); + +#endif /* CONFIG_TRACING */ + +#endif /* _LINUX_TRACE_H */ diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8696ce6..038291d 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -40,6 +40,7 @@ #include <linux/poll.h> #include <linux/nmi.h> #include <linux/fs.h> +#include <linux/trace.h> #include <linux/sched/rt.h> #include "trace.h" @@ -2128,6 +2129,129 @@ void trace_buffer_unlock_commit_regs(struct trace_array *tr, ftrace_trace_userstack(buffer, flags, pc); } +static void +trace_process_export(struct trace_export *export, + struct ring_buffer_event *event) +{ + struct trace_entry *entry; + unsigned int size = 0; + + entry = ring_buffer_event_data(event); + size = ring_buffer_event_length(event); + export->write(entry, size); +} + +static DEFINE_MUTEX(ftrace_export_lock); + +static struct trace_export __rcu *ftrace_exports_list __read_mostly; + +static DEFINE_STATIC_KEY_FALSE(ftrace_exports_enabled); + +static inline void ftrace_exports_enable(void) +{ + static_branch_enable(&ftrace_exports_enabled); +} + +static inline void ftrace_exports_disable(void) +{ + static_branch_disable(&ftrace_exports_enabled); +} + +void ftrace_exports(struct ring_buffer_event *event) +{ + struct trace_export *export; + + preempt_disable_notrace(); + + export = rcu_dereference_raw_notrace(ftrace_exports_list); + while (export) { + trace_process_export(export, event); + export = rcu_dereference_raw_notrace(export->next); + } + + preempt_enable_notrace(); +} + +static inline void +add_trace_export(struct trace_export **list, struct trace_export *export) +{ + rcu_assign_pointer(export->next, *list); + /* + * We are entering export into the list but another + * CPU might be walking that list. We need to make sure + * the export->next pointer is valid before another CPU sees + * the export pointer included into the list. + */ + rcu_assign_pointer(*list, export); +} + +static inline int +rm_trace_export(struct trace_export **list, struct trace_export *export) +{ + struct trace_export **p; + + for (p = list; *p != NULL; p = &(*p)->next) + if (*p == export) + break; + + if (*p != export) + return -1; + + rcu_assign_pointer(*p, (*p)->next); + + return 0; +} + +static inline void +add_ftrace_export(struct trace_export **list, struct trace_export *export) +{ + if (*list == NULL) + ftrace_exports_enable(); + + add_trace_export(list, export); +} + +static inline int +rm_ftrace_export(struct trace_export **list, struct trace_export *export) +{ + int ret; + + ret = rm_trace_export(list, export); + if (*list == NULL) + ftrace_exports_disable(); + + return ret; +} + +int register_ftrace_export(struct trace_export *export) +{ + if (WARN_ON_ONCE(!export->write)) + return -1; + + mutex_lock(&ftrace_export_lock); + + add_ftrace_export(&ftrace_exports_list, export); + + mutex_unlock(&ftrace_export_lock); + + return 0; +} +EXPORT_SYMBOL_GPL(register_ftrace_export); + +int unregister_ftrace_export(struct trace_export *export) +{ + int ret; + + mutex_lock(&ftrace_export_lock); + + ret = rm_ftrace_export(&ftrace_exports_list, export); + + mutex_unlock(&ftrace_export_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(unregister_ftrace_export); + void trace_function(struct trace_array *tr, unsigned long ip, unsigned long parent_ip, unsigned long flags, @@ -2146,8 +2270,11 @@ trace_function(struct trace_array *tr, entry->ip = ip; entry->parent_ip = parent_ip; - if (!call_filter_check_discard(call, entry, buffer, event)) + if (!call_filter_check_discard(call, entry, buffer, event)) { + if (static_branch_unlikely(&ftrace_exports_enabled)) + ftrace_exports(event); __buffer_unlock_commit(buffer, event); + } } #ifdef CONFIG_STACKTRACE
Currently Function traces can be only exported to ring buffer, this patch added trace_export concept which can process traces and export them to a registered destination as an addition to the current only one output of Ftrace - i.e. ring buffer. In this way, if we want Function traces to be sent to other destination rather than ring buffer only, we just need to register a new trace_export and implement its own .write() function for writing traces to storage. With this patch, only Function trace (trace type is TRACE_FN) is supported. Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org> --- include/linux/trace.h | 28 +++++++++++ kernel/trace/trace.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 156 insertions(+), 1 deletion(-) create mode 100644 include/linux/trace.h -- 2.7.4