From fb40bd78b0f91b274879cf5db8facd1e04b6052e Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Wed, 13 Feb 2008 15:03:37 -0800 Subject: 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: Mathieu Desnoyers Cc: Christoph Hellwig Cc: Mike Mason Cc: Dipankar Sarma Cc: David Smith Cc: "Paul E. McKenney" Cc: "Frank Ch. Eigler" Cc: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/marker.h | 59 ++++++++++++++++++++++++++++++-------------------- include/linux/module.h | 2 +- 2 files changed, 37 insertions(+), 24 deletions(-) (limited to 'include/linux') diff --git a/include/linux/marker.h b/include/linux/marker.h index 5f36cf946bc..b5f95637f28 100644 --- a/include/linux/marker.h +++ b/include/linux/marker.h @@ -19,16 +19,23 @@ struct marker; /** * marker_probe_func - Type of a marker probe function - * @mdata: pointer of type struct marker - * @private_data: caller site private data + * @probe_private: probe private data + * @call_private: call site private data * @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 * format string to recover the variable argument list. */ -typedef void marker_probe_func(const struct marker *mdata, - void *private_data, const char *fmt, ...); +typedef void marker_probe_func(void *probe_private, void *call_private, + const char *fmt, va_list *args); + +struct marker_probe_closure { + marker_probe_func *func; /* Callback */ + void *probe_private; /* Private probe data */ +}; struct marker { const char *name; /* Marker name */ @@ -36,8 +43,11 @@ struct marker { * variable argument list. */ char state; /* Marker state. */ - marker_probe_func *call;/* Probe handler function pointer */ - void *private; /* Private probe data */ + char ptype; /* probe type : 0 : single, 1 : multi */ + 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))); #ifdef CONFIG_MARKERS @@ -49,7 +59,7 @@ struct marker { * not add unwanted padding between the beginning of the section and the * 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 { \ static const char __mstrtab_name_##name[] \ __attribute__((section("__markers_strings"))) \ @@ -60,24 +70,23 @@ struct marker { static struct marker __mark_##name \ __attribute__((section("__markers"), aligned(8))) = \ { __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); \ if (unlikely(__mark_##name.state)) { \ - preempt_disable(); \ (*__mark_##name.call) \ - (&__mark_##name, call_data, \ + (&__mark_##name, call_private, \ format, ## args); \ - preempt_enable(); \ } \ } while (0) extern void marker_update_probe_range(struct marker *begin, - struct marker *end, struct module *probe_module, int *refcount); + struct marker *end); #else /* !CONFIG_MARKERS */ -#define __trace_mark(name, call_data, format, args...) \ +#define __trace_mark(name, call_private, format, args...) \ __mark_check_format(format, ## args) 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 */ @@ -92,8 +101,6 @@ static inline void marker_update_probe_range(struct marker *begin, #define trace_mark(name, format, args...) \ __trace_mark(name, NULL, format, ## args) -#define MARK_MAX_FORMAT_LEN 1024 - /** * 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, ...) 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. * private data pointer must be a valid allocated memory address, or NULL. */ 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. */ -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. */ -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 int marker_disarm(const char *name); -extern void *marker_get_private_data(const char *name); +extern void *marker_get_private_data(const char *name, marker_probe_func *probe, + int num); #endif diff --git a/include/linux/module.h b/include/linux/module.h index ac28e8761e8..330bec08c2c 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -465,7 +465,7 @@ int unregister_module_notifier(struct notifier_block * nb); 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... */ #define EXPORT_SYMBOL(sym) -- cgit v1.2.3