#include <urcu/hlist.h>
#include <urcu/uatomic.h>
#include <urcu/compiler.h>
+#include <urcu/system.h>
#include <lttng/tracepoint.h>
#include <lttng/ust-abi.h> /* for LTTNG_UST_SYM_NAME_LEN */
#include "jhash.h"
#include "error.h"
+/* Test compiler support for weak symbols with hidden visibility. */
+int __tracepoint_test_symbol1 __attribute__((weak, visibility("hidden")));
+void *__tracepoint_test_symbol2 __attribute__((weak, visibility("hidden")));
+struct {
+ char a[24];
+} __tracepoint_test_symbol3 __attribute__((weak, visibility("hidden")));
+
/* Set to 1 to enable tracepoint debug output */
static const int tracepoint_debug;
static int initialized;
-static void (*new_tracepoint_cb)(struct tracepoint *);
+static void (*new_tracepoint_cb)(struct lttng_ust_tracepoint *);
/*
* tracepoint_mutex nests inside UST mutex.
static CDS_LIST_HEAD(old_probes);
static int need_update;
+static CDS_LIST_HEAD(release_queue);
+static int release_queue_need_update;
+
/*
* Note about RCU :
* It is used to to delay the free of multiple probes array until a quiescent
*/
struct tracepoint_entry {
struct cds_hlist_node hlist;
- struct tracepoint_probe *probes;
+ struct lttng_ust_tracepoint_probe *probes;
int refcount; /* Number of times armed. 0 if disarmed. */
int callsite_refcount; /* how many libs use this tracepoint */
- const char *signature;
- char name[0];
+ char *signature;
+ char *name;
};
struct tp_probes {
/* Field below only used for call_rcu scheme */
/* struct rcu_head head; */
} u;
- struct tracepoint_probe probes[0];
+ struct lttng_ust_tracepoint_probe probes[0];
};
/*
struct callsite_entry {
struct cds_hlist_node hlist; /* hash table node */
struct cds_list_head node; /* lib list of callsites node */
- struct tracepoint *tp;
+ struct lttng_ust_tracepoint *tp;
+ bool tp_entry_callsite_ref; /* Has a tp_entry took a ref on this callsite */
};
/* coverity[+alloc] */
static void *allocate_probes(int count)
{
- struct tp_probes *p = zmalloc(count * sizeof(struct tracepoint_probe)
- + sizeof(struct tp_probes));
+ struct tp_probes *p =
+ zmalloc(count * sizeof(struct lttng_ust_tracepoint_probe)
+ + sizeof(struct tp_probes));
return p == NULL ? NULL : p->probes;
}
void (*probe)(void), void *data)
{
int nr_probes = 0;
- struct tracepoint_probe *old, *new;
+ struct lttng_ust_tracepoint_probe *old, *new;
if (!probe) {
WARN_ON(1);
if (new == NULL)
return ERR_PTR(-ENOMEM);
if (old)
- memcpy(new, old, nr_probes * sizeof(struct tracepoint_probe));
+ memcpy(new, old,
+ nr_probes * sizeof(struct lttng_ust_tracepoint_probe));
new[nr_probes].func = probe;
new[nr_probes].data = data;
new[nr_probes + 1].func = NULL;
void (*probe)(void), void *data)
{
int nr_probes = 0, nr_del = 0, i;
- struct tracepoint_probe *old, *new;
+ struct lttng_ust_tracepoint_probe *old, *new;
old = entry->probes;
struct cds_hlist_node *node;
struct tracepoint_entry *e;
size_t name_len = strlen(name);
+ size_t sig_len = strlen(signature);
+ size_t sig_off, name_off;
uint32_t hash;
if (name_len > LTTNG_UST_SYM_NAME_LEN - 1) {
return ERR_PTR(-EEXIST); /* Already there */
}
}
+
/*
- * Using zmalloc here to allocate a variable length element. Could
- * cause some memory fragmentation if overused.
+ * Using zmalloc here to allocate a variable length elements: name and
+ * signature. Could cause some memory fragmentation if overused.
*/
- e = zmalloc(sizeof(struct tracepoint_entry) + name_len + 1);
+ name_off = sizeof(struct tracepoint_entry);
+ sig_off = name_off + name_len + 1;
+
+ e = zmalloc(sizeof(struct tracepoint_entry) + name_len + 1 + sig_len + 1);
if (!e)
return ERR_PTR(-ENOMEM);
- memcpy(&e->name[0], name, name_len + 1);
+ e->name = (char *) e + name_off;
+ memcpy(e->name, name, name_len + 1);
e->name[name_len] = '\0';
+
+ e->signature = (char *) e + sig_off;
+ memcpy(e->signature, signature, sig_len + 1);
+ e->signature[sig_len] = '\0';
+
e->probes = NULL;
e->refcount = 0;
e->callsite_refcount = 0;
- e->signature = signature;
+
cds_hlist_add_head(&e->hlist, head);
return e;
}
* Sets the probe callback corresponding to one tracepoint.
*/
static void set_tracepoint(struct tracepoint_entry **entry,
- struct tracepoint *elem, int active)
+ struct lttng_ust_tracepoint *elem, int active)
{
WARN_ON(strncmp((*entry)->name, elem->name, LTTNG_UST_SYM_NAME_LEN - 1) != 0);
/*
* is used.
*/
rcu_assign_pointer(elem->probes, (*entry)->probes);
- elem->state = active;
+ CMM_STORE_SHARED(elem->state, active);
}
/*
* 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 void disable_tracepoint(struct lttng_ust_tracepoint *elem)
{
- elem->state = 0;
+ CMM_STORE_SHARED(elem->state, 0);
rcu_assign_pointer(elem->probes, NULL);
}
* Add the callsite to the callsite hash table. Must be called with
* tracepoint mutex held.
*/
-static void add_callsite(struct tracepoint_lib * lib, struct tracepoint *tp)
+static void add_callsite(struct tracepoint_lib * lib, struct lttng_ust_tracepoint *tp)
{
struct cds_hlist_head *head;
struct callsite_entry *e;
hash = jhash(name, name_len, 0);
head = &callsite_table[hash & (CALLSITE_TABLE_SIZE - 1)];
e = zmalloc(sizeof(struct callsite_entry));
- assert(e);
+ if (!e) {
+ PERROR("Unable to add callsite for tracepoint \"%s\"", name);
+ return;
+ }
cds_hlist_add_head(&e->hlist, head);
e->tp = tp;
cds_list_add(&e->node, &lib->callsites);
if (!tp_entry)
return;
tp_entry->callsite_refcount++;
+ e->tp_entry_callsite_ref = true;
}
/*
tp_entry = get_tracepoint(e->tp->name);
if (tp_entry) {
- tp_entry->callsite_refcount--;
+ if (e->tp_entry_callsite_ref)
+ tp_entry->callsite_refcount--;
if (tp_entry->callsite_refcount == 0)
disable_tracepoint(e->tp);
}
hash = jhash(name, name_len, 0);
head = &callsite_table[hash & (CALLSITE_TABLE_SIZE - 1)];
cds_hlist_for_each_entry(e, node, head, hlist) {
- struct tracepoint *tp = e->tp;
+ struct lttng_ust_tracepoint *tp = e->tp;
if (strncmp(name, tp->name, LTTNG_UST_SYM_NAME_LEN - 1))
continue;
if (tp_entry) {
+ if (!e->tp_entry_callsite_ref) {
+ tp_entry->callsite_refcount++;
+ e->tp_entry_callsite_ref = true;
+ }
set_tracepoint(&tp_entry, tp,
!!tp_entry->refcount);
} else {
disable_tracepoint(tp);
+ e->tp_entry_callsite_ref = false;
}
}
}
* Updates the probe callback corresponding to a range of tracepoints.
*/
static
-void tracepoint_update_probe_range(struct tracepoint * const *begin,
- struct tracepoint * const *end)
+void tracepoint_update_probe_range(struct lttng_ust_tracepoint * const *begin,
+ struct lttng_ust_tracepoint * const *end)
{
- struct tracepoint * const *iter;
+ struct lttng_ust_tracepoint * const *iter;
struct tracepoint_entry *mark_entry;
for (iter = begin; iter < end; iter++) {
static void lib_register_callsites(struct tracepoint_lib *lib)
{
- struct tracepoint * const *begin;
- struct tracepoint * const *end;
- struct tracepoint * const *iter;
+ struct lttng_ust_tracepoint * const *begin;
+ struct lttng_ust_tracepoint * const *end;
+ struct lttng_ust_tracepoint * const *iter;
begin = lib->tracepoints_start;
end = lib->tracepoints_start + lib->tracepoints_count;
lib_update_tracepoints(lib);
}
-static struct tracepoint_probe *
+static struct lttng_ust_tracepoint_probe *
tracepoint_add_probe(const char *name, void (*probe)(void), void *data,
const char *signature)
{
struct tracepoint_entry *entry;
- struct tracepoint_probe *old;
+ struct lttng_ust_tracepoint_probe *old;
entry = get_tracepoint(name);
- if (!entry) {
+ if (entry) {
+ if (strcmp(entry->signature, signature) != 0) {
+ ERR("Tracepoint and probe signature do not match.");
+ return ERR_PTR(-EINVAL);
+ }
+ } else {
entry = add_tracepoint(name, signature);
if (IS_ERR(entry))
- return (struct tracepoint_probe *)entry;
+ return (struct lttng_ust_tracepoint_probe *)entry;
}
old = tracepoint_entry_add_probe(entry, probe, data);
if (IS_ERR(old) && !entry->refcount)
return old;
}
+static void tracepoint_release_queue_add_old_probes(void *old)
+{
+ release_queue_need_update = 1;
+ if (old) {
+ struct tp_probes *tp_probes = caa_container_of(old,
+ struct tp_probes, probes[0]);
+ cds_list_add(&tp_probes->u.list, &release_queue);
+ }
+}
+
/**
* __tracepoint_probe_register - Connect a probe to a tracepoint
* @name: tracepoint name
return ret;
}
+/*
+ * Caller needs to invoke __tracepoint_probe_release_queue() after
+ * calling __tracepoint_probe_register_queue_release() one or multiple
+ * times to ensure it does not leak memory.
+ */
+int __tracepoint_probe_register_queue_release(const char *name,
+ void (*probe)(void), void *data, const char *signature)
+{
+ void *old;
+ int ret = 0;
+
+ DBG("Registering probe to tracepoint %s. Queuing release.", name);
+
+ pthread_mutex_lock(&tracepoint_mutex);
+ old = tracepoint_add_probe(name, probe, data, signature);
+ if (IS_ERR(old)) {
+ ret = PTR_ERR(old);
+ goto end;
+ }
+
+ tracepoint_sync_callsites(name);
+ tracepoint_release_queue_add_old_probes(old);
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
+ return ret;
+}
+
static void *tracepoint_remove_probe(const char *name, void (*probe)(void),
void *data)
{
return ret;
}
+/*
+ * Caller needs to invoke __tracepoint_probe_release_queue() after
+ * calling __tracepoint_probe_unregister_queue_release() one or multiple
+ * times to ensure it does not leak memory.
+ */
+int __tracepoint_probe_unregister_queue_release(const char *name,
+ void (*probe)(void), void *data)
+{
+ void *old;
+ int ret = 0;
+
+ DBG("Un-registering probe from tracepoint %s. Queuing release.", name);
+
+ pthread_mutex_lock(&tracepoint_mutex);
+ old = tracepoint_remove_probe(name, probe, data);
+ if (IS_ERR(old)) {
+ ret = PTR_ERR(old);
+ goto end;
+ }
+ tracepoint_sync_callsites(name);
+ tracepoint_release_queue_add_old_probes(old);
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
+ return ret;
+}
+
+void __tracepoint_probe_prune_release_queue(void)
+{
+ CDS_LIST_HEAD(release_probes);
+ struct tp_probes *pos, *next;
+
+ DBG("Release queue of unregistered tracepoint probes.");
+
+ pthread_mutex_lock(&tracepoint_mutex);
+ if (!release_queue_need_update)
+ goto end;
+ if (!cds_list_empty(&release_queue))
+ cds_list_replace_init(&release_queue, &release_probes);
+ release_queue_need_update = 0;
+
+ /* Wait for grace period between all sync_callsites and free. */
+ synchronize_rcu();
+
+ cds_list_for_each_entry_safe(pos, next, &release_probes, u.list) {
+ cds_list_del(&pos->u.list);
+ free(pos);
+ }
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
+}
+
static void tracepoint_add_old_probes(void *old)
{
need_update = 1;
need_update = 0;
tracepoint_update_probes();
+ /* Wait for grace period between update_probes and free. */
+ synchronize_rcu();
cds_list_for_each_entry_safe(pos, next, &release_probes, u.list) {
cds_list_del(&pos->u.list);
- synchronize_rcu();
free(pos);
}
end:
pthread_mutex_unlock(&tracepoint_mutex);
}
-void tracepoint_set_new_tracepoint_cb(void (*cb)(struct tracepoint *))
+void tracepoint_set_new_tracepoint_cb(void (*cb)(struct lttng_ust_tracepoint *))
{
new_tracepoint_cb = cb;
}
-static void new_tracepoints(struct tracepoint * const *start, struct tracepoint * const *end)
+static void new_tracepoints(struct lttng_ust_tracepoint * const *start,
+ struct lttng_ust_tracepoint * const *end)
{
if (new_tracepoint_cb) {
- struct tracepoint * const *t;
+ struct lttng_ust_tracepoint * const *t;
for (t = start; t < end; t++) {
if (*t)
}
}
-int tracepoint_register_lib(struct tracepoint * const *tracepoints_start,
+int tracepoint_register_lib(struct lttng_ust_tracepoint * const *tracepoints_start,
int tracepoints_count)
{
struct tracepoint_lib *pl, *iter;
init_tracepoint();
pl = (struct tracepoint_lib *) zmalloc(sizeof(struct tracepoint_lib));
-
+ if (!pl) {
+ PERROR("Unable to register tracepoint lib");
+ return -1;
+ }
pl->tracepoints_start = tracepoints_start;
pl->tracepoints_count = tracepoints_count;
CDS_INIT_LIST_HEAD(&pl->callsites);
return 0;
}
-int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start)
+int tracepoint_unregister_lib(struct lttng_ust_tracepoint * const *tracepoints_start)
{
struct tracepoint_lib *lib;
return 0;
}
+/*
+ * Report in debug message whether the compiler correctly supports weak
+ * hidden symbols. This test checks that the address associated with two
+ * weak symbols with hidden visibility is the same when declared within
+ * two compile units part of the same module.
+ */
+static void check_weak_hidden(void)
+{
+ DBG("Your compiler treats weak symbols with hidden visibility for integer objects as %s between compile units part of the same module.",
+ &__tracepoint_test_symbol1 == lttng_ust_tp_check_weak_hidden1() ?
+ "SAME address" :
+ "DIFFERENT addresses");
+ DBG("Your compiler treats weak symbols with hidden visibility for pointer objects as %s between compile units part of the same module.",
+ &__tracepoint_test_symbol2 == lttng_ust_tp_check_weak_hidden2() ?
+ "SAME address" :
+ "DIFFERENT addresses");
+ DBG("Your compiler treats weak symbols with hidden visibility for 24-byte structure objects as %s between compile units part of the same module.",
+ &__tracepoint_test_symbol3 == lttng_ust_tp_check_weak_hidden3() ?
+ "SAME address" :
+ "DIFFERENT addresses");
+}
+
void init_tracepoint(void)
{
if (uatomic_xchg(&initialized, 1) == 1)
return;
init_usterr();
+ check_weak_hidden();
}
void exit_tracepoint(void)
projects / lttng-ust.git / blobdiff