#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 */
struct cds_hlist_node hlist;
struct 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];
};
struct tracepoint *tp;
};
+/* coverity[+alloc] */
static void *allocate_probes(int count)
{
struct tp_probes *p = zmalloc(count * sizeof(struct tracepoint_probe)
return p == NULL ? NULL : p->probes;
}
+/* coverity[+free : arg-0] */
static void release_probes(void *old)
{
if (old) {
e->name[name_len] = '\0';
e->probes = NULL;
e->refcount = 0;
+ e->callsite_refcount = 0;
e->signature = signature;
cds_hlist_add_head(&e->hlist, head);
return e;
free(e);
}
-/*
- * Add the callsite to the callsite hash table. Must be called with
- * tracepoint mutex held.
- */
-static void add_callsite(struct tracepoint *tp)
-{
- struct cds_hlist_head *head;
- struct callsite_entry *e;
- const char *name = tp->name;
- size_t name_len = strlen(name);
- uint32_t hash;
-
- if (name_len > LTTNG_UST_SYM_NAME_LEN - 1) {
- WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_SYM_NAME_LEN - 1);
- name_len = LTTNG_UST_SYM_NAME_LEN - 1;
- }
- hash = jhash(name, name_len, 0);
- head = &callsite_table[hash & (CALLSITE_TABLE_SIZE - 1)];
- e = zmalloc(sizeof(struct callsite_entry));
- assert(e);
- cds_hlist_add_head(&e->hlist, head);
- e->tp = tp;
-}
-
-/*
- * Remove the callsite from the callsite hash table and from lib
- * callsite list. Must be called with tracepoint mutex held.
- */
-static void remove_callsite(struct callsite_entry *e)
-{
- cds_hlist_del(&e->hlist);
- cds_list_del(&e->node);
- free(e);
-}
-
/*
* Sets the probe callback corresponding to one tracepoint.
*/
* is used.
*/
rcu_assign_pointer(elem->probes, (*entry)->probes);
- elem->state = active;
+ CMM_STORE_SHARED(elem->state, active);
}
/*
*/
static void disable_tracepoint(struct 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)
+{
+ struct cds_hlist_head *head;
+ struct callsite_entry *e;
+ const char *name = tp->name;
+ size_t name_len = strlen(name);
+ uint32_t hash;
+ struct tracepoint_entry *tp_entry;
+
+ if (name_len > LTTNG_UST_SYM_NAME_LEN - 1) {
+ WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_SYM_NAME_LEN - 1);
+ name_len = LTTNG_UST_SYM_NAME_LEN - 1;
+ }
+ hash = jhash(name, name_len, 0);
+ head = &callsite_table[hash & (CALLSITE_TABLE_SIZE - 1)];
+ e = zmalloc(sizeof(struct callsite_entry));
+ 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);
+
+ tp_entry = get_tracepoint(name);
+ if (!tp_entry)
+ return;
+ tp_entry->callsite_refcount++;
+}
+
+/*
+ * Remove the callsite from the callsite hash table and from lib
+ * callsite list. Must be called with tracepoint mutex held.
+ */
+static void remove_callsite(struct callsite_entry *e)
+{
+ struct tracepoint_entry *tp_entry;
+
+ tp_entry = get_tracepoint(e->tp->name);
+ if (tp_entry) {
+ tp_entry->callsite_refcount--;
+ if (tp_entry->callsite_refcount == 0)
+ disable_tracepoint(e->tp);
+ }
+ cds_hlist_del(&e->hlist);
+ cds_list_del(&e->node);
+ free(e);
+}
+
/*
* Enable/disable all callsites based on the state of a specific
* tracepoint entry.
if (!(*iter)->name) {
continue;
}
- add_callsite(*iter);
+ add_callsite(lib, *iter);
}
}
}
}
-static
-void lib_disable_tracepoints(struct tracepoint_lib *lib)
-{
- struct tracepoint * const *begin;
- struct tracepoint * const *end;
- struct tracepoint * const *iter;
-
- begin = lib->tracepoints_start;
- end = lib->tracepoints_start + lib->tracepoints_count;
-
- for (iter = begin; iter < end; iter++) {
- if (!*iter)
- continue; /* skip dummy */
- disable_tracepoint(*iter);
- }
-
-}
-
int tracepoint_register_lib(struct tracepoint * const *tracepoints_start,
int tracepoints_count)
{
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);
cds_list_del(&lib->list);
/*
- * Force tracepoint disarm for all tracepoints of this lib.
- * This takes care of destructor of library that would leave a
- * LD_PRELOAD wrapper override function enabled for tracing, but
- * the session teardown would not be able to reach the
- * tracepoint anymore to disable it.
+ * Unregistering a callsite also decreases the
+ * callsite reference count of the corresponding
+ * tracepoint, and disables the tracepoint if
+ * the reference count drops to zero.
*/
- lib_disable_tracepoints(lib);
lib_unregister_callsites(lib);
DBG("just unregistered a tracepoints section from %p",
lib->tracepoints_start);
projects / lttng-ust.git / blobdiff