Commit fb40bd78 authored by Mathieu Desnoyers's avatar Mathieu Desnoyers Committed by Linus Torvalds

Linux Kernel Markers: support multiple probes

RCU style multiple probes support for the Linux Kernel Markers.  Common case
(one probe) is still fast and does not require dynamic allocation or a
supplementary pointer dereference on the fast path.

- Move preempt disable from the marker site to the callback.

Since we now have an internal callback, move the preempt disable/enable to the
callback instead of the marker site.

Since the callback change is done asynchronously (passing from a handler that
supports arguments to a handler that does not setup the arguments is no
arguments are passed), we can safely update it even if it is outside the
preempt disable section.

- Move probe arm to probe connection. Now, a connected probe is automatically
  armed.

Remove MARK_MAX_FORMAT_LEN, unused.

This patch modifies the Linux Kernel Markers API : it removes the probe
"arm/disarm" and changes the probe function prototype : it now expects a
va_list * instead of a "...".

If we want to have more than one probe connected to a marker at a given
time (LTTng, or blktrace, ssytemtap) then we need this patch. Without it,
connecting a second probe handler to a marker will fail.

It allow us, for instance, to do interesting combinations :

Do standard tracing with LTTng and, eventually, to compute statistics
with SystemTAP, or to have a special trigger on an event that would call
a systemtap script which would stop flight recorder tracing.
Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Mike Mason <mmlnx@us.ibm.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: David Smith <dsmith@redhat.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9170d2f6
...@@ -146,34 +146,28 @@ static void sputrace_log_item(const char *name, struct spu_context *ctx, ...@@ -146,34 +146,28 @@ static void sputrace_log_item(const char *name, struct spu_context *ctx,
wake_up(&sputrace_wait); wake_up(&sputrace_wait);
} }
static void spu_context_event(const struct marker *mdata, static void spu_context_event(void *probe_private, void *call_data,
void *private, const char *format, ...) const char *format, va_list *args)
{ {
struct spu_probe *p = mdata->private; struct spu_probe *p = probe_private;
va_list ap;
struct spu_context *ctx; struct spu_context *ctx;
struct spu *spu; struct spu *spu;
va_start(ap, format); ctx = va_arg(*args, struct spu_context *);
ctx = va_arg(ap, struct spu_context *); spu = va_arg(*args, struct spu *);
spu = va_arg(ap, struct spu *);
sputrace_log_item(p->name, ctx, spu); sputrace_log_item(p->name, ctx, spu);
va_end(ap);
} }
static void spu_context_nospu_event(const struct marker *mdata, static void spu_context_nospu_event(void *probe_private, void *call_data,
void *private, const char *format, ...) const char *format, va_list *args)
{ {
struct spu_probe *p = mdata->private; struct spu_probe *p = probe_private;
va_list ap;
struct spu_context *ctx; struct spu_context *ctx;
va_start(ap, format); ctx = va_arg(*args, struct spu_context *);
ctx = va_arg(ap, struct spu_context *);
sputrace_log_item(p->name, ctx, NULL); sputrace_log_item(p->name, ctx, NULL);
va_end(ap);
} }
struct spu_probe spu_probes[] = { struct spu_probe spu_probes[] = {
...@@ -219,10 +213,6 @@ static int __init sputrace_init(void) ...@@ -219,10 +213,6 @@ static int __init sputrace_init(void)
if (error) if (error)
printk(KERN_INFO "Unable to register probe %s\n", printk(KERN_INFO "Unable to register probe %s\n",
p->name); p->name);
error = marker_arm(p->name);
if (error)
printk(KERN_INFO "Unable to arm probe %s\n", p->name);
} }
return 0; return 0;
...@@ -238,7 +228,8 @@ static void __exit sputrace_exit(void) ...@@ -238,7 +228,8 @@ static void __exit sputrace_exit(void)
int i; int i;
for (i = 0; i < ARRAY_SIZE(spu_probes); i++) for (i = 0; i < ARRAY_SIZE(spu_probes); i++)
marker_probe_unregister(spu_probes[i].name); marker_probe_unregister(spu_probes[i].name,
spu_probes[i].probe_func, &spu_probes[i]);
remove_proc_entry("sputrace", NULL); remove_proc_entry("sputrace", NULL);
kfree(sputrace_log); kfree(sputrace_log);
......
...@@ -19,16 +19,23 @@ struct marker; ...@@ -19,16 +19,23 @@ struct marker;
/** /**
* marker_probe_func - Type of a marker probe function * marker_probe_func - Type of a marker probe function
* @mdata: pointer of type struct marker * @probe_private: probe private data
* @private_data: caller site private data * @call_private: call site private data
* @fmt: format string * @fmt: format string
* @...: variable argument list * @args: variable argument list pointer. Use a pointer to overcome C's
* inability to pass this around as a pointer in a portable manner in
* the callee otherwise.
* *
* Type of marker probe functions. They receive the mdata and need to parse the * Type of marker probe functions. They receive the mdata and need to parse the
* format string to recover the variable argument list. * format string to recover the variable argument list.
*/ */
typedef void marker_probe_func(const struct marker *mdata, typedef void marker_probe_func(void *probe_private, void *call_private,
void *private_data, const char *fmt, ...); const char *fmt, va_list *args);
struct marker_probe_closure {
marker_probe_func *func; /* Callback */
void *probe_private; /* Private probe data */
};
struct marker { struct marker {
const char *name; /* Marker name */ const char *name; /* Marker name */
...@@ -36,8 +43,11 @@ struct marker { ...@@ -36,8 +43,11 @@ struct marker {
* variable argument list. * variable argument list.
*/ */
char state; /* Marker state. */ char state; /* Marker state. */
marker_probe_func *call;/* Probe handler function pointer */ char ptype; /* probe type : 0 : single, 1 : multi */
void *private; /* Private probe data */ void (*call)(const struct marker *mdata, /* Probe wrapper */
void *call_private, const char *fmt, ...);
struct marker_probe_closure single;
struct marker_probe_closure *multi;
} __attribute__((aligned(8))); } __attribute__((aligned(8)));
#ifdef CONFIG_MARKERS #ifdef CONFIG_MARKERS
...@@ -49,7 +59,7 @@ struct marker { ...@@ -49,7 +59,7 @@ struct marker {
* not add unwanted padding between the beginning of the section and the * not add unwanted padding between the beginning of the section and the
* structure. Force alignment to the same alignment as the section start. * structure. Force alignment to the same alignment as the section start.
*/ */
#define __trace_mark(name, call_data, format, args...) \ #define __trace_mark(name, call_private, format, args...) \
do { \ do { \
static const char __mstrtab_name_##name[] \ static const char __mstrtab_name_##name[] \
__attribute__((section("__markers_strings"))) \ __attribute__((section("__markers_strings"))) \
...@@ -60,24 +70,23 @@ struct marker { ...@@ -60,24 +70,23 @@ struct marker {
static struct marker __mark_##name \ static struct marker __mark_##name \
__attribute__((section("__markers"), aligned(8))) = \ __attribute__((section("__markers"), aligned(8))) = \
{ __mstrtab_name_##name, __mstrtab_format_##name, \ { __mstrtab_name_##name, __mstrtab_format_##name, \
0, __mark_empty_function, NULL }; \ 0, 0, marker_probe_cb, \
{ __mark_empty_function, NULL}, NULL }; \
__mark_check_format(format, ## args); \ __mark_check_format(format, ## args); \
if (unlikely(__mark_##name.state)) { \ if (unlikely(__mark_##name.state)) { \
preempt_disable(); \
(*__mark_##name.call) \ (*__mark_##name.call) \
(&__mark_##name, call_data, \ (&__mark_##name, call_private, \
format, ## args); \ format, ## args); \
preempt_enable(); \
} \ } \
} while (0) } while (0)
extern void marker_update_probe_range(struct marker *begin, extern void marker_update_probe_range(struct marker *begin,
struct marker *end, struct module *probe_module, int *refcount); struct marker *end);
#else /* !CONFIG_MARKERS */ #else /* !CONFIG_MARKERS */
#define __trace_mark(name, call_data, format, args...) \ #define __trace_mark(name, call_private, format, args...) \
__mark_check_format(format, ## args) __mark_check_format(format, ## args)
static inline void marker_update_probe_range(struct marker *begin, static inline void marker_update_probe_range(struct marker *begin,
struct marker *end, struct module *probe_module, int *refcount) struct marker *end)
{ } { }
#endif /* CONFIG_MARKERS */ #endif /* CONFIG_MARKERS */
...@@ -92,8 +101,6 @@ static inline void marker_update_probe_range(struct marker *begin, ...@@ -92,8 +101,6 @@ static inline void marker_update_probe_range(struct marker *begin,
#define trace_mark(name, format, args...) \ #define trace_mark(name, format, args...) \
__trace_mark(name, NULL, format, ## args) __trace_mark(name, NULL, format, ## args)
#define MARK_MAX_FORMAT_LEN 1024
/** /**
* MARK_NOARGS - Format string for a marker with no argument. * MARK_NOARGS - Format string for a marker with no argument.
*/ */
...@@ -106,24 +113,30 @@ static inline void __printf(1, 2) __mark_check_format(const char *fmt, ...) ...@@ -106,24 +113,30 @@ static inline void __printf(1, 2) __mark_check_format(const char *fmt, ...)
extern marker_probe_func __mark_empty_function; extern marker_probe_func __mark_empty_function;
extern void marker_probe_cb(const struct marker *mdata,
void *call_private, const char *fmt, ...);
extern void marker_probe_cb_noarg(const struct marker *mdata,
void *call_private, const char *fmt, ...);
/* /*
* Connect a probe to a marker. * Connect a probe to a marker.
* private data pointer must be a valid allocated memory address, or NULL. * private data pointer must be a valid allocated memory address, or NULL.
*/ */
extern int marker_probe_register(const char *name, const char *format, extern int marker_probe_register(const char *name, const char *format,
marker_probe_func *probe, void *private); marker_probe_func *probe, void *probe_private);
/* /*
* Returns the private data given to marker_probe_register. * Returns the private data given to marker_probe_register.
*/ */
extern void *marker_probe_unregister(const char *name); extern int marker_probe_unregister(const char *name,
marker_probe_func *probe, void *probe_private);
/* /*
* Unregister a marker by providing the registered private data. * Unregister a marker by providing the registered private data.
*/ */
extern void *marker_probe_unregister_private_data(void *private); extern int marker_probe_unregister_private_data(marker_probe_func *probe,
void *probe_private);
extern int marker_arm(const char *name); extern void *marker_get_private_data(const char *name, marker_probe_func *probe,
extern int marker_disarm(const char *name); int num);
extern void *marker_get_private_data(const char *name);
#endif #endif
...@@ -465,7 +465,7 @@ int unregister_module_notifier(struct notifier_block * nb); ...@@ -465,7 +465,7 @@ int unregister_module_notifier(struct notifier_block * nb);
extern void print_modules(void); extern void print_modules(void);
extern void module_update_markers(struct module *probe_module, int *refcount); extern void module_update_markers(void);
#else /* !CONFIG_MODULES... */ #else /* !CONFIG_MODULES... */
#define EXPORT_SYMBOL(sym) #define EXPORT_SYMBOL(sym)
......
This diff is collapsed.
...@@ -2038,7 +2038,7 @@ static struct module *load_module(void __user *umod, ...@@ -2038,7 +2038,7 @@ static struct module *load_module(void __user *umod,
#ifdef CONFIG_MARKERS #ifdef CONFIG_MARKERS
if (!mod->taints) if (!mod->taints)
marker_update_probe_range(mod->markers, marker_update_probe_range(mod->markers,
mod->markers + mod->num_markers, NULL, NULL); mod->markers + mod->num_markers);
#endif #endif
err = module_finalize(hdr, sechdrs, mod); err = module_finalize(hdr, sechdrs, mod);
if (err < 0) if (err < 0)
...@@ -2564,7 +2564,7 @@ EXPORT_SYMBOL(struct_module); ...@@ -2564,7 +2564,7 @@ EXPORT_SYMBOL(struct_module);
#endif #endif
#ifdef CONFIG_MARKERS #ifdef CONFIG_MARKERS
void module_update_markers(struct module *probe_module, int *refcount) void module_update_markers(void)
{ {
struct module *mod; struct module *mod;
...@@ -2572,8 +2572,7 @@ void module_update_markers(struct module *probe_module, int *refcount) ...@@ -2572,8 +2572,7 @@ void module_update_markers(struct module *probe_module, int *refcount)
list_for_each_entry(mod, &modules, list) list_for_each_entry(mod, &modules, list)
if (!mod->taints) if (!mod->taints)
marker_update_probe_range(mod->markers, marker_update_probe_range(mod->markers,
mod->markers + mod->num_markers, mod->markers + mod->num_markers);
probe_module, refcount);
mutex_unlock(&module_mutex); mutex_unlock(&module_mutex);
} }
#endif #endif
...@@ -20,31 +20,27 @@ struct probe_data { ...@@ -20,31 +20,27 @@ struct probe_data {
marker_probe_func *probe_func; marker_probe_func *probe_func;
}; };
void probe_subsystem_event(const struct marker *mdata, void *private, void probe_subsystem_event(void *probe_data, void *call_data,
const char *format, ...) const char *format, va_list *args)
{ {
va_list ap;
/* Declare args */ /* Declare args */
unsigned int value; unsigned int value;
const char *mystr; const char *mystr;
/* Assign args */ /* Assign args */
va_start(ap, format); value = va_arg(*args, typeof(value));
value = va_arg(ap, typeof(value)); mystr = va_arg(*args, typeof(mystr));
mystr = va_arg(ap, typeof(mystr));
/* Call printk */ /* Call printk */
printk(KERN_DEBUG "Value %u, string %s\n", value, mystr); printk(KERN_INFO "Value %u, string %s\n", value, mystr);
/* or count, check rights, serialize data in a buffer */ /* or count, check rights, serialize data in a buffer */
va_end(ap);
} }
atomic_t eventb_count = ATOMIC_INIT(0); atomic_t eventb_count = ATOMIC_INIT(0);
void probe_subsystem_eventb(const struct marker *mdata, void *private, void probe_subsystem_eventb(void *probe_data, void *call_data,
const char *format, ...) const char *format, va_list *args)
{ {
/* Increment counter */ /* Increment counter */
atomic_inc(&eventb_count); atomic_inc(&eventb_count);
...@@ -72,10 +68,6 @@ static int __init probe_init(void) ...@@ -72,10 +68,6 @@ static int __init probe_init(void)
if (result) if (result)
printk(KERN_INFO "Unable to register probe %s\n", printk(KERN_INFO "Unable to register probe %s\n",
probe_array[i].name); probe_array[i].name);
result = marker_arm(probe_array[i].name);
if (result)
printk(KERN_INFO "Unable to arm probe %s\n",
probe_array[i].name);
} }
return 0; return 0;
} }
...@@ -85,7 +77,8 @@ static void __exit probe_fini(void) ...@@ -85,7 +77,8 @@ static void __exit probe_fini(void)
int i; int i;
for (i = 0; i < ARRAY_SIZE(probe_array); i++) for (i = 0; i < ARRAY_SIZE(probe_array); i++)
marker_probe_unregister(probe_array[i].name); marker_probe_unregister(probe_array[i].name,
probe_array[i].probe_func, &probe_array[i]);
printk(KERN_INFO "Number of event b : %u\n", printk(KERN_INFO "Number of event b : %u\n",
atomic_read(&eventb_count)); atomic_read(&eventb_count));
} }
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment