[PATCH v7 2/2] Tracepoint: register/unregister struct tracepoint

From: Mathieu Desnoyers
Date: Fri Mar 21 2014 - 01:19:32 EST

Register/unregister tracepoint probes with struct tracepoint pointer
rather than tracepoint name.

This change, which vastly simplifies tracepoint.c, has been proposed by
Steven Rostedt.

>From this point on, the tracers need to pass a struct tracepoint pointer
to probe register/unregister. A probe can now only be connected to a
tracepoint that exists. Moreover, tracers are responsible for
unregistering the probe before the module containing its associated
tracepoint is unloaded.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
CC: Steven Rostedt <rostedt@xxxxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxxxxx>
CC: Frederic Weisbecker <fweisbec@xxxxxxxxx>
CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
CC: Frank Ch. Eigler <fche@xxxxxxxxxx>
CC: Johannes Berg <johannes.berg@xxxxxxxxx>
---
include/linux/ftrace_event.h | 1 +
include/linux/tracepoint.h | 42 ++--
include/trace/ftrace.h | 2 +
kernel/trace/trace_events.c | 8 +-
kernel/tracepoint.c | 524 ++++++++++++++++++++----------------------
5 files changed, 275 insertions(+), 302 deletions(-)

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 4e4cc28..1592c1c 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -230,6 +230,7 @@ struct ftrace_event_call {
struct list_head list;
struct ftrace_event_class *class;
char *name;
+ struct tracepoint *tp;
struct trace_event event;
const char *print_fmt;
struct event_filter *filter;
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 812b255..3144d12 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -6,7 +6,7 @@
*
* See Documentation/trace/tracepoints.txt.
*
- * (C) Copyright 2008 Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>
+ * Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
*
* Heavily inspired from the Linux Kernel Markers.
*
@@ -21,6 +21,7 @@

struct module;
struct tracepoint;
+struct notifier_block;

struct tracepoint_func {
void *func;
@@ -35,18 +36,12 @@ struct tracepoint {
struct tracepoint_func __rcu *funcs;
};

-/*
- * Connect a probe to a tracepoint.
- * Internal API, should not be used directly.
- */
-extern int tracepoint_probe_register(const char *name, void *probe, void *data);
-
-/*
- * Disconnect a probe from a tracepoint.
- * Internal API, should not be used directly.
- */
-extern int
-tracepoint_probe_unregister(const char *name, void *probe, void *data);
+extern
+int tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
+extern
+int tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
+void for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
+ void *priv);

#ifdef CONFIG_MODULES
struct tp_module {
@@ -54,12 +49,25 @@ struct tp_module {
unsigned int num_tracepoints;
struct tracepoint * const *tracepoints_ptrs;
};
+
bool trace_module_has_bad_taint(struct module *mod);
+int register_tracepoint_module_notifier(struct notifier_block *nb);
+int unregister_tracepoint_module_notifier(struct notifier_block *nb);
#else
static inline bool trace_module_has_bad_taint(struct module *mod)
{
return false;
}
+static inline
+int register_tracepoint_module_notifier(struct notifier_block *nb)
+{
+ return 0;
+}
+static inline
+int unregister_tracepoint_module_notifier(struct notifier_block *nb)
+{
+ return 0;
+}
#endif /* CONFIG_MODULES */

/*
@@ -160,14 +168,14 @@ static inline void tracepoint_synchronize_unregister(void)
static inline int \
register_trace_##name(void (*probe)(data_proto), void *data) \
{ \
- return tracepoint_probe_register(#name, (void *)probe, \
- data); \
+ return tracepoint_probe_register(&__tracepoint_##name, \
+ (void *)probe, data); \
} \
static inline int \
unregister_trace_##name(void (*probe)(data_proto), void *data) \
{ \
- return tracepoint_probe_unregister(#name, (void *)probe, \
- data); \
+ return tracepoint_probe_unregister(&__tracepoint_##name,\
+ (void *)probe, data); \
} \
static inline void \
check_trace_callback_type_##name(void (*cb)(data_proto)) \
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 1a8b28d..415b986 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -625,6 +625,7 @@ static struct ftrace_event_class __used __refdata event_class_##call = { \
\
static struct ftrace_event_call __used event_##call = { \
.name = #call, \
+ .tp = &__tracepoint_##call, \
.class = &event_class_##template, \
.event.funcs = &ftrace_event_type_funcs_##template, \
.print_fmt = print_fmt_##template, \
@@ -639,6 +640,7 @@ static const char print_fmt_##call[] = print; \
\
static struct ftrace_event_call __used event_##call = { \
.name = #call, \
+ .tp = &__tracepoint_##call, \
.class = &event_class_##template, \
.event.funcs = &ftrace_event_type_funcs_##call, \
.print_fmt = print_fmt_##call, \
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index f3989ce..0e39692 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -201,22 +201,22 @@ int ftrace_event_reg(struct ftrace_event_call *call,

switch (type) {
case TRACE_REG_REGISTER:
- return tracepoint_probe_register(call->name,
+ return tracepoint_probe_register(call->tp,
call->class->probe,
file);
case TRACE_REG_UNREGISTER:
- tracepoint_probe_unregister(call->name,
+ tracepoint_probe_unregister(call->tp,
call->class->probe,
file);
return 0;

#ifdef CONFIG_PERF_EVENTS
case TRACE_REG_PERF_REGISTER:
- return tracepoint_probe_register(call->name,
+ return tracepoint_probe_register(call->tp,
call->class->perf_probe,
call);
case TRACE_REG_PERF_UNREGISTER:
- tracepoint_probe_unregister(call->name,
+ tracepoint_probe_unregister(call->tp,
call->class->perf_probe,
call);
return 0;
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index f27e5f0..85dc2f2 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -1,5 +1,5 @@
/*
- * Copyright (C) 2008 Mathieu Desnoyers
+ * Copyright (C) 2008-2014 Mathieu Desnoyers
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@@ -33,38 +33,27 @@ extern struct tracepoint * const __stop___tracepoints_ptrs[];
/* Set to 1 to enable tracepoint debug output */
static const int tracepoint_debug;

+#ifdef CONFIG_MODULES
/*
- * Tracepoints mutex protects the builtin and module tracepoints and the hash
- * table, as well as the local module list.
+ * Tracepoint module list mutex protects the local module list.
*/
-static DEFINE_MUTEX(tracepoints_mutex);
+static DEFINE_MUTEX(tp_modlist_mutex);

-#ifdef CONFIG_MODULES
-/* Local list of struct module */
-static LIST_HEAD(tracepoint_module_list);
+/* Local list of struct tp_module */
+static LIST_HEAD(tp_modlist);
#endif /* CONFIG_MODULES */

/*
- * Tracepoint hash table, containing the active tracepoints.
- * Protected by tracepoints_mutex.
+ * tracepoint_mutex protects the builtin and module tracepoints.
+ * tracepoint_mutex nests inside tp_modlist_mutex.
*/
-#define TRACEPOINT_HASH_BITS 6
-#define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
-static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];
+static DEFINE_MUTEX(tracepoint_mutex);

/*
* Note about RCU :
* It is used to delay the free of multiple probes array until a quiescent
* state is reached.
- * Tracepoint entries modifications are protected by the tracepoints_mutex.
*/
-struct tracepoint_entry {
- struct hlist_node hlist;
- struct tracepoint_func *funcs;
- int refcount; /* Number of times armed. 0 if disarmed. */
- char name[0];
-};
-
struct tp_probes {
struct rcu_head rcu;
struct tracepoint_func probes[0];
@@ -91,34 +80,35 @@ static inline void release_probes(struct tracepoint_func *old)
}
}

-static void debug_print_probes(struct tracepoint_entry *entry)
+static
+void debug_print_probes(struct tracepoint_func *funcs)
{
int i;

- if (!tracepoint_debug || !entry->funcs)
+ if (!tracepoint_debug || !funcs)
return;

- for (i = 0; entry->funcs[i].func; i++)
- printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i].func);
+ for (i = 0; funcs[i].func; i++)
+ printk(KERN_DEBUG "Probe %d : %p\n", i, funcs[i].func);
}

-static struct tracepoint_func *
-tracepoint_entry_add_probe(struct tracepoint_entry *entry,
- void *probe, void *data)
+static
+struct tracepoint_func *func_add(struct tracepoint_func **funcs,
+ struct tracepoint_func *tp_func)
{
int nr_probes = 0;
struct tracepoint_func *old, *new;

- if (WARN_ON(!probe))
+ if (WARN_ON(!tp_func->func))
return ERR_PTR(-EINVAL);

- debug_print_probes(entry);
- old = entry->funcs;
+ debug_print_probes(*funcs);
+ old = *funcs;
if (old) {
/* (N -> N+1), (N != 0, 1) probes */
for (nr_probes = 0; old[nr_probes].func; nr_probes++)
- if (old[nr_probes].func == probe &&
- old[nr_probes].data == data)
+ if (old[nr_probes].func == tp_func->func &&
+ old[nr_probes].data == tp_func->data)
return ERR_PTR(-EEXIST);
}
/* + 2 : one for new probe, one for NULL func */
@@ -127,33 +117,31 @@ tracepoint_entry_add_probe(struct tracepoint_entry *entry,
return ERR_PTR(-ENOMEM);
if (old)
memcpy(new, old, nr_probes * sizeof(struct tracepoint_func));
- new[nr_probes].func = probe;
- new[nr_probes].data = data;
+ new[nr_probes] = *tp_func;
new[nr_probes + 1].func = NULL;
- entry->refcount = nr_probes + 1;
- entry->funcs = new;
- debug_print_probes(entry);
+ *funcs = new;
+ debug_print_probes(*funcs);
return old;
}

-static void *
-tracepoint_entry_remove_probe(struct tracepoint_entry *entry,
- void *probe, void *data)
+static
+void *func_remove(struct tracepoint_func **funcs,
+ struct tracepoint_func *tp_func)
{
int nr_probes = 0, nr_del = 0, i;
struct tracepoint_func *old, *new;

- old = entry->funcs;
+ old = *funcs;

if (!old)
return ERR_PTR(-ENOENT);

- debug_print_probes(entry);
+ debug_print_probes(*funcs);
/* (N -> M), (N > 1, M >= 0) probes */
- if (probe) {
+ if (tp_func->func) {
for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
- if (old[nr_probes].func == probe &&
- old[nr_probes].data == data)
+ if (old[nr_probes].func == tp_func->func &&
+ old[nr_probes].data == tp_func->data)
nr_del++;
}
}
@@ -164,9 +152,8 @@ tracepoint_entry_remove_probe(struct tracepoint_entry *entry,
*/
if (nr_probes - nr_del == 0) {
/* N -> 0, (N > 1) */
- entry->funcs = NULL;
- entry->refcount = 0;
- debug_print_probes(entry);
+ *funcs = NULL;
+ debug_print_probes(*funcs);
return old;
} else {
int j = 0;
@@ -176,90 +163,35 @@ tracepoint_entry_remove_probe(struct tracepoint_entry *entry,
if (new == NULL)
return ERR_PTR(-ENOMEM);
for (i = 0; old[i].func; i++)
- if (old[i].func != probe || old[i].data != data)
+ if (old[i].func != tp_func->func
+ || old[i].data != tp_func->data)
new[j++] = old[i];
new[nr_probes - nr_del].func = NULL;
- entry->refcount = nr_probes - nr_del;
- entry->funcs = new;
+ *funcs = new;
}
- debug_print_probes(entry);
+ debug_print_probes(*funcs);
return old;
}

/*
- * Get tracepoint if the tracepoint is present in the tracepoint hash table.
- * Must be called with tracepoints_mutex held.
- * Returns NULL if not present.
- */
-static struct tracepoint_entry *get_tracepoint(const char *name)
-{
- struct hlist_head *head;
- struct tracepoint_entry *e;
- u32 hash = jhash(name, strlen(name), 0);
-
- head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
- hlist_for_each_entry(e, head, hlist) {
- if (!strcmp(name, e->name))
- return e;
- }
- return NULL;
-}
-
-/*
- * Add the tracepoint to the tracepoint hash table. Must be called with
- * tracepoints_mutex held.
- */
-static struct tracepoint_entry *add_tracepoint(const char *name)
-{
- struct hlist_head *head;
- struct tracepoint_entry *e;
- size_t name_len = strlen(name) + 1;
- u32 hash = jhash(name, name_len-1, 0);
-
- head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
- hlist_for_each_entry(e, head, hlist) {
- if (!strcmp(name, e->name)) {
- printk(KERN_NOTICE
- "tracepoint %s busy\n", name);
- return ERR_PTR(-EEXIST); /* Already there */
- }
- }
- /*
- * Using kmalloc here to allocate a variable length element. Could
- * cause some memory fragmentation if overused.
- */
- e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL);
- if (!e)
- return ERR_PTR(-ENOMEM);
- memcpy(&e->name[0], name, name_len);
- e->funcs = NULL;
- e->refcount = 0;
- hlist_add_head(&e->hlist, head);
- return e;
-}
-
-/*
- * Remove the tracepoint from the tracepoint hash table. Must be called with
- * mutex_lock held.
+ * Add the probe function to a tracepoint.
*/
-static inline void remove_tracepoint(struct tracepoint_entry *e)
+static
+int tracepoint_add_func(struct tracepoint *tp,
+ struct tracepoint_func *func)
{
- hlist_del(&e->hlist);
- kfree(e);
-}
+ struct tracepoint_func *old, *tp_funcs;

-/*
- * Sets the probe callback corresponding to one tracepoint.
- */
-static void set_tracepoint(struct tracepoint_entry **entry,
- struct tracepoint *elem, int active)
-{
- WARN_ON(strcmp((*entry)->name, elem->name) != 0);
+ if (tp->regfunc && !static_key_enabled(&tp->key))
+ tp->regfunc();

- if (elem->regfunc && !static_key_enabled(&elem->key) && active)
- elem->regfunc();
- else if (elem->unregfunc && static_key_enabled(&elem->key) && !active)
- elem->unregfunc();
+ tp_funcs = tp->funcs;
+ old = func_add(&tp_funcs, func);
+ if (IS_ERR(old)) {
+ WARN_ON_ONCE(1);
+ return PTR_ERR(old);
+ }
+ release_probes(old);

/*
* rcu_assign_pointer has a smp_wmb() which makes sure that the new
@@ -268,192 +200,180 @@ static void set_tracepoint(struct tracepoint_entry **entry,
* include/linux/tracepoints.h. A matching smp_read_barrier_depends()
* is used.
*/
- rcu_assign_pointer(elem->funcs, (*entry)->funcs);
- if (active && !static_key_enabled(&elem->key))
- static_key_slow_inc(&elem->key);
- else if (!active && static_key_enabled(&elem->key))
- static_key_slow_dec(&elem->key);
+ rcu_assign_pointer(tp->funcs, tp_funcs);
+ if (!static_key_enabled(&tp->key))
+ static_key_slow_inc(&tp->key);
+ return 0;
}

/*
- * Disable a tracepoint and its probe callback.
+ * Remove a probe function from a tracepoint.
* Note: only waiting an RCU period after setting elem->call to the empty
* function insures that the original callback is not used anymore. This insured
* by preempt_disable around the call site.
*/
-static void disable_tracepoint(struct tracepoint *elem)
+static
+int tracepoint_remove_func(struct tracepoint *tp,
+ struct tracepoint_func *func)
{
- if (elem->unregfunc && static_key_enabled(&elem->key))
- elem->unregfunc();
-
- if (static_key_enabled(&elem->key))
- static_key_slow_dec(&elem->key);
- rcu_assign_pointer(elem->funcs, NULL);
-}
+ struct tracepoint_func *old, *tp_funcs;

-/**
- * tracepoint_update_probe_range - Update a probe range
- * @begin: beginning of the range
- * @end: end of the range
- *
- * Updates the probe callback corresponding to a range of tracepoints.
- * Called with tracepoints_mutex held.
- */
-static void tracepoint_update_probe_range(struct tracepoint * const *begin,
- struct tracepoint * const *end)
-{
- struct tracepoint * const *iter;
- struct tracepoint_entry *mark_entry;
+ tp_funcs = tp->funcs;
+ old = func_remove(&tp_funcs, func);
+ if (IS_ERR(old)) {
+ WARN_ON_ONCE(1);
+ return PTR_ERR(old);
+ }
+ release_probes(old);

- if (!begin)
- return;
+ if (!tp_funcs) {
+ /* Removed last function */
+ if (tp->unregfunc && static_key_enabled(&tp->key))
+ tp->unregfunc();

- for (iter = begin; iter < end; iter++) {
- mark_entry = get_tracepoint((*iter)->name);
- if (mark_entry) {
- set_tracepoint(&mark_entry, *iter,
- !!mark_entry->refcount);
- } else {
- disable_tracepoint(*iter);
- }
+ if (static_key_enabled(&tp->key))
+ static_key_slow_dec(&tp->key);
}
+ rcu_assign_pointer(tp->funcs, tp_funcs);
+ return 0;
}

-#ifdef CONFIG_MODULES
-void module_update_tracepoints(void)
-{
- struct tp_module *tp_mod;
-
- list_for_each_entry(tp_mod, &tracepoint_module_list, list)
- tracepoint_update_probe_range(tp_mod->tracepoints_ptrs,
- tp_mod->tracepoints_ptrs + tp_mod->num_tracepoints);
-}
-#else /* CONFIG_MODULES */
-void module_update_tracepoints(void)
+/**
+ * tracepoint_probe_register - Connect a probe to a tracepoint
+ * @tp: tracepoint
+ * @probe: probe handler
+ *
+ * Returns 0 if ok, error value on error.
+ * Note: if @tp is within a module, the caller is responsible for
+ * unregistering the probe before the module is gone. This can be
+ * performed either with a tracepoint module going notifier, or from
+ * within module exit functions.
+ */
+int tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data)
{
+ struct tracepoint_func tp_func;
+ int ret;
+
+ mutex_lock(&tracepoint_mutex);
+ tp_func.func = probe;
+ tp_func.data = data;
+ ret = tracepoint_add_func(tp, &tp_func);
+ mutex_unlock(&tracepoint_mutex);
+ return ret;
}
-#endif /* CONFIG_MODULES */
-
+EXPORT_SYMBOL_GPL(tracepoint_probe_register);

-/*
- * Update probes, removing the faulty probes.
- * Called with tracepoints_mutex held.
+/**
+ * tracepoint_probe_unregister - Disconnect a probe from a tracepoint
+ * @tp: tracepoint
+ * @probe: probe function pointer
+ *
+ * Returns 0 if ok, error value on error.
*/
-static void tracepoint_update_probes(void)
+int tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data)
{
- /* Core kernel tracepoints */
- tracepoint_update_probe_range(__start___tracepoints_ptrs,
- __stop___tracepoints_ptrs);
- /* tracepoints in modules. */
- module_update_tracepoints();
+ struct tracepoint_func tp_func;
+ int ret;
+
+ mutex_lock(&tracepoint_mutex);
+ tp_func.func = probe;
+ tp_func.data = data;
+ ret = tracepoint_remove_func(tp, &tp_func);
+ mutex_unlock(&tracepoint_mutex);
+ return ret;
}
+EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);

-static struct tracepoint_func *
-tracepoint_add_probe(const char *name, void *probe, void *data)
+#ifdef CONFIG_MODULES
+bool trace_module_has_bad_taint(struct module *mod)
{
- struct tracepoint_entry *entry;
- struct tracepoint_func *old;
-
- entry = get_tracepoint(name);
- if (!entry) {
- entry = add_tracepoint(name);
- if (IS_ERR(entry))
- return (struct tracepoint_func *)entry;
- }
- old = tracepoint_entry_add_probe(entry, probe, data);
- if (IS_ERR(old) && !entry->refcount)
- remove_tracepoint(entry);
- return old;
+ return mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP));
}

+static BLOCKING_NOTIFIER_HEAD(tracepoint_notify_list);
+
/**
- * tracepoint_probe_register - Connect a probe to a tracepoint
- * @name: tracepoint name
- * @probe: probe handler
+ * register_tracepoint_notifier - register tracepoint coming/going notifier
+ * @nb: notifier block
*
- * Returns 0 if ok, error value on error.
- * The probe address must at least be aligned on the architecture pointer size.
+ * Notifiers registered with this function are called on module
+ * coming/going with the tp_modlist_mutex held.
+ * The notifier block callback should expect a "struct tp_module" data
+ * pointer.
*/
-int tracepoint_probe_register(const char *name, void *probe, void *data)
-{
- struct tracepoint_func *old;
-
- mutex_lock(&tracepoints_mutex);
- old = tracepoint_add_probe(name, probe, data);
- if (IS_ERR(old)) {
- mutex_unlock(&tracepoints_mutex);
- return PTR_ERR(old);
- }
- tracepoint_update_probes(); /* may update entry */
- mutex_unlock(&tracepoints_mutex);
- release_probes(old);
- return 0;
-}
-EXPORT_SYMBOL_GPL(tracepoint_probe_register);
-
-static struct tracepoint_func *
-tracepoint_remove_probe(const char *name, void *probe, void *data)
+int register_tracepoint_module_notifier(struct notifier_block *nb)
{
- struct tracepoint_entry *entry;
- struct tracepoint_func *old;
+ struct tp_module *tp_mod;
+ int ret;

- entry = get_tracepoint(name);
- if (!entry)
- return ERR_PTR(-ENOENT);
- old = tracepoint_entry_remove_probe(entry, probe, data);
- if (IS_ERR(old))
- return old;
- if (!entry->refcount)
- remove_tracepoint(entry);
- return old;
+ mutex_lock(&tp_modlist_mutex);
+ ret = blocking_notifier_chain_register(&tracepoint_notify_list, nb);
+ if (ret)
+ goto end;
+ list_for_each_entry(tp_mod, &tp_modlist, list)
+ (void) nb->notifier_call(nb, MODULE_STATE_COMING, tp_mod);
+end:
+ mutex_unlock(&tp_modlist_mutex);
+ return ret;
}
+EXPORT_SYMBOL_GPL(register_tracepoint_module_notifier);

/**
- * tracepoint_probe_unregister - Disconnect a probe from a tracepoint
- * @name: tracepoint name
- * @probe: probe function pointer
+ * unregister_tracepoint_notifier - unregister tracepoint coming/going notifier
+ * @nb: notifier block
*
- * We do not need to call a synchronize_sched to make sure the probes have
- * finished running before doing a module unload, because the module unload
- * itself uses stop_machine(), which insures that every preempt disabled section
- * have finished.
+ * The notifier block callback should expect a "struct tp_module" data
+ * pointer.
*/
-int tracepoint_probe_unregister(const char *name, void *probe, void *data)
+int unregister_tracepoint_module_notifier(struct notifier_block *nb)
{
- struct tracepoint_func *old;
+ struct tp_module *tp_mod;
+ int ret;
+
+ mutex_lock(&tp_modlist_mutex);
+ ret = blocking_notifier_chain_unregister(&tracepoint_notify_list, nb);
+ if (ret)
+ goto end;
+ list_for_each_entry(tp_mod, &tp_modlist, list)
+ (void) nb->notifier_call(nb, MODULE_STATE_GOING, tp_mod);
+end:
+ mutex_unlock(&tp_modlist_mutex);
+ return ret;

- mutex_lock(&tracepoints_mutex);
- old = tracepoint_remove_probe(name, probe, data);
- if (IS_ERR(old)) {
- mutex_unlock(&tracepoints_mutex);
- return PTR_ERR(old);
- }
- tracepoint_update_probes(); /* may update entry */
- mutex_unlock(&tracepoints_mutex);
- release_probes(old);
- return 0;
}
-EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
+EXPORT_SYMBOL_GPL(unregister_tracepoint_module_notifier);

-#ifdef CONFIG_MODULES
-bool trace_module_has_bad_taint(struct module *mod)
+/*
+ * Ensure the tracer unregistered the module's probes before the module
+ * teardown is performed. Prevents leaks of probe and data pointers.
+ */
+static
+void tp_module_going_check_quiescent(struct tracepoint * const *begin,
+ struct tracepoint * const *end)
{
- return mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP));
+ struct tracepoint * const *iter;
+
+ if (!begin)
+ return;
+ for (iter = begin; iter < end; iter++)
+ WARN_ON_ONCE((*iter)->funcs);
}

-static int tracepoint_module_coming(struct module *mod)
+static
+int tracepoint_module_coming(struct module *mod)
{
struct tp_module *tp_mod;
int ret = 0;

/*
- * We skip modules that taint the kernel, especially those with different
- * module headers (for forced load), to make sure we don't cause a crash.
- * Staging and out-of-tree GPL modules are fine.
+ * We skip modules that taint the kernel, especially those with
+ * different module headers (for forced load), to make sure we
+ * don't cause a crash. Staging and out-of-tree GPL modules are
+ * fine.
*/
if (trace_module_has_bad_taint(mod))
return 0;
- mutex_lock(&tracepoints_mutex);
+ mutex_lock(&tp_modlist_mutex);
tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL);
if (!tp_mod) {
ret = -ENOMEM;
@@ -461,25 +381,32 @@ static int tracepoint_module_coming(struct module *mod)
}
tp_mod->num_tracepoints = mod->num_tracepoints;
tp_mod->tracepoints_ptrs = mod->tracepoints_ptrs;
- list_add_tail(&tp_mod->list, &tracepoint_module_list);
- tracepoint_update_probe_range(mod->tracepoints_ptrs,
- mod->tracepoints_ptrs + mod->num_tracepoints);
+ list_add_tail(&tp_mod->list, &tp_modlist);
+ blocking_notifier_call_chain(&tracepoint_notify_list,
+ MODULE_STATE_COMING, tp_mod);
end:
- mutex_unlock(&tracepoints_mutex);
+ mutex_unlock(&tp_modlist_mutex);
return ret;
}

-static int tracepoint_module_going(struct module *mod)
+static
+void tracepoint_module_going(struct module *mod)
{
- struct tp_module *pos;
-
- mutex_lock(&tracepoints_mutex);
- tracepoint_update_probe_range(mod->tracepoints_ptrs,
- mod->tracepoints_ptrs + mod->num_tracepoints);
- list_for_each_entry(pos, &tracepoint_module_list, list) {
- if (pos->tracepoints_ptrs == mod->tracepoints_ptrs) {
- list_del(&pos->list);
- kfree(pos);
+ struct tp_module *tp_mod;
+
+ mutex_lock(&tp_modlist_mutex);
+ list_for_each_entry(tp_mod, &tp_modlist, list) {
+ if (tp_mod->tracepoints_ptrs == mod->tracepoints_ptrs) {
+ blocking_notifier_call_chain(&tracepoint_notify_list,
+ MODULE_STATE_GOING, tp_mod);
+ list_del(&tp_mod->list);
+ kfree(tp_mod);
+ /*
+ * Called the going notifier before checking for
+ * quiescence.
+ */
+ tp_module_going_check_quiescent(mod->tracepoints_ptrs,
+ mod->tracepoints_ptrs + mod->num_tracepoints);
break;
}
}
@@ -489,12 +416,12 @@ static int tracepoint_module_going(struct module *mod)
* flag on "going", in case a module taints the kernel only after being
* loaded.
*/
- mutex_unlock(&tracepoints_mutex);
- return 0;
+ mutex_unlock(&tp_modlist_mutex);
}

+static
int tracepoint_module_notify(struct notifier_block *self,
- unsigned long val, void *data)
+ unsigned long val, void *data)
{
struct module *mod = data;
int ret = 0;
@@ -503,30 +430,65 @@ int tracepoint_module_notify(struct notifier_block *self,
case MODULE_STATE_COMING:
ret = tracepoint_module_coming(mod);
break;
- case MODULE_STATE_LIVE:
- break;
case MODULE_STATE_GOING:
- ret = tracepoint_module_going(mod);
+ tracepoint_module_going(mod);
+ break;
+ default:
break;
}
return ret;
}

+static
struct notifier_block tracepoint_module_nb = {
.notifier_call = tracepoint_module_notify,
.priority = 0,
};

-static int init_tracepoints(void)
+static __init
+int init_tracepoints(void)
{
- return register_module_notifier(&tracepoint_module_nb);
+ int ret;
+
+ ret = register_module_notifier(&tracepoint_module_nb);
+ if (ret) {
+ pr_warning("Failed to register tracepoint module enter notifier\n");
+ }
+ return ret;
}
__initcall(init_tracepoints);
#endif /* CONFIG_MODULES */

+static
+void for_each_tracepoint_range(struct tracepoint * const *begin,
+ struct tracepoint * const *end,
+ void (*fct)(struct tracepoint *tp, void *priv),
+ void *priv)
+{
+ struct tracepoint * const *iter;
+
+ if (!begin)
+ return;
+ for (iter = begin; iter < end; iter++)
+ fct(*iter, priv);
+}
+
+/**
+ * for_each_kernel_tracepoint - iteration on all kernel tracepoints
+ * @fct: callback
+ * @priv: private data
+ */
+void for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
+ void *priv)
+{
+ for_each_tracepoint_range(__start___tracepoints_ptrs,
+ __stop___tracepoints_ptrs, fct, priv);
+}
+EXPORT_SYMBOL_GPL(for_each_kernel_tracepoint);
+
#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS

-/* NB: reg/unreg are called while guarded with the tracepoints_mutex */
+/* NB: reg/unreg are called while guarded with the tracepoint_mutex */
static int sys_tracepoint_refcount;

void syscall_regfunc(void)
--
1.7.10.4

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