Fix: add lttng rcu wrapper to allow tracing RCU

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/lttng-tracker-pid.c b/lttng-tracker-pid.c
index eeee9d55a5b844106178d5186c37ef61012aa2e3..55bf63c994de212ea34a372be80a033d9bcc2be7 100644 (file)
--- a/lttng-tracker-pid.c
+++ b/lttng-tracker-pid.c
@@ -29,6 +29,7 @@
 #include <linux/rcupdate.h>
 
 #include "wrapper/tracepoint.h"
+#include "wrapper/rcu.h"
 #include "wrapper/list.h"
 #include "lttng-events.h"
 
@@ -59,7 +60,7 @@ bool lttng_pid_tracker_lookup(struct lttng_pid_tracker *lpf, int pid)
        uint32_t hash = hash_32(pid, 32);
 
        head = &lpf->pid_hash[hash & (LTTNG_PID_TABLE_SIZE - 1)];
-       lttng_hlist_for_each_entry_rcu_notrace(e, head, hlist) {
+       lttng_hlist_for_each_entry_rcu(e, head, hlist) {
                if (pid == e->pid)
                        return 1;       /* Found */
        }

diff --git a/probes/lttng-events.h b/probes/lttng-events.h
index 29b44af71d9316b0701adfba64dc4312c3c403e7..58f4e1200d860f6b01294e6a1b6f341300cb1d09 100644 (file)
--- a/probes/lttng-events.h
+++ b/probes/lttng-events.h
@@ -27,6 +27,7 @@
 #include "lttng-probe-user.h"
 #include "../wrapper/vmalloc.h"        /* for wrapper_vmalloc_sync_all() */
 #include "../wrapper/ringbuffer/frontend_types.h"
+#include "../wrapper/rcu.h"
 #include "../lttng-events.h"
 #include "../lttng-tracer-core.h"
 
@@ -728,7 +729,7 @@ static void __event_probe__##_name(void *__data, _proto)                  \
                return;                                                       \
        if (unlikely(!ACCESS_ONCE(__event->enabled)))                         \
                return;                                                       \
-       __lpf = rcu_dereference(__session->pid_tracker);                      \
+       __lpf = lttng_rcu_dereference(__session->pid_tracker);                \
        if (__lpf && likely(!lttng_pid_tracker_lookup(__lpf, current->pid)))  \
                return;                                                       \
        _code                                                                 \
@@ -738,7 +739,7 @@ static void __event_probe__##_name(void *__data, _proto)                  \
                                                                              \
                __event_prepare_filter_stack__##_name(__stackvar.__filter_stack_data, \
                                tp_locvar, _args);                                    \
-               list_for_each_entry_rcu(bc_runtime, &__event->bytecode_runtime_head, node) { \
+               lttng_list_for_each_entry_rcu(bc_runtime, &__event->bytecode_runtime_head, node) { \
                        if (unlikely(bc_runtime->filter(bc_runtime,           \
                                        __stackvar.__filter_stack_data) & LTTNG_FILTER_RECORD_FLAG)) \
                                __filter_record = 1;                          \
@@ -787,7 +788,7 @@ static void __event_probe__##_name(void *__data)                          \
                return;                                                       \
        if (unlikely(!ACCESS_ONCE(__event->enabled)))                         \
                return;                                                       \
-       __lpf = rcu_dereference(__session->pid_tracker);                      \
+       __lpf = lttng_rcu_dereference(__session->pid_tracker);                \
        if (__lpf && likely(!lttng_pid_tracker_lookup(__lpf, current->pid)))  \
                return;                                                       \
        _code                                                                 \
@@ -797,7 +798,7 @@ static void __event_probe__##_name(void *__data)                          \
                                                                              \
                __event_prepare_filter_stack__##_name(__stackvar.__filter_stack_data, \
                                tp_locvar);                                   \
-               list_for_each_entry_rcu(bc_runtime, &__event->bytecode_runtime_head, node) { \
+               lttng_list_for_each_entry_rcu(bc_runtime, &__event->bytecode_runtime_head, node) { \
                        if (unlikely(bc_runtime->filter(bc_runtime,           \
                                        __stackvar.__filter_stack_data) & LTTNG_FILTER_RECORD_FLAG)) \
                                __filter_record = 1;                          \

diff --git a/wrapper/list.h b/wrapper/list.h
index c816684ddf7eb35fd5421f285b80e5182c1ff305..0d79e5128c7b36555fee4a266d24a99a2550054a 100644 (file)
--- a/wrapper/list.h
+++ b/wrapper/list.h
@@ -57,28 +57,4 @@
             pos && ({ n = pos->member.next; 1; });                     \
             pos = lttng_hlist_entry_safe(n, typeof(*pos), member))
 
-#ifndef rcu_dereference_raw_notrace
-#define rcu_dereference_raw_notrace(p) rcu_dereference_raw(p)
-#endif
-
-/**
- * lttng_hlist_for_each_entry_rcu_notrace - iterate over rcu list of given type (for tracing)
- * @pos:       the type * to use as a loop cursor.
- * @head:      the head for your list.
- * @member:    the name of the hlist_node within the struct.
- *
- * This list-traversal primitive may safely run concurrently with
- * the _rcu list-mutation primitives such as hlist_add_head_rcu()
- * as long as the traversal is guarded by rcu_read_lock().
- *
- * This is the same as hlist_for_each_entry_rcu() except that it does
- * not do any RCU debugging or tracing.
- */
-#define lttng_hlist_for_each_entry_rcu_notrace(pos, head, member)      \
-       for (pos = lttng_hlist_entry_safe (rcu_dereference_raw_notrace(hlist_first_rcu(head)),\
-                       typeof(*(pos)), member);                        \
-               pos;                                                    \
-               pos = lttng_hlist_entry_safe(rcu_dereference_raw_notrace(hlist_next_rcu(\
-                       &(pos)->member)), typeof(*(pos)), member))
-
 #endif /* _LTTNG_WRAPPER_LIST_H */

diff --git a/wrapper/rcu.h b/wrapper/rcu.h
new file mode 100644 (file)
index 0000000..d96d42d
--- /dev/null
+++ b/wrapper/rcu.h
@@ -0,0 +1,90 @@
+#ifndef _LTTNG_WRAPPER_RCU_H
+#define _LTTNG_WRAPPER_RCU_H
+
+/*
+ * wrapper/rcu.h
+ *
+ * wrapper around linux/rcupdate.h and linux/rculist.h.
+ *
+ * Copyright (C) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <linux/version.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
+#include "list.h"
+
+#ifndef rcu_dereference_raw_notrace
+#define rcu_dereference_raw_notrace(p) rcu_dereference_raw(p)
+#endif
+
+#define lttng_rcu_dereference(p) rcu_dereference_raw_notrace(p)
+
+/**
+ * lttng_list_entry_rcu - get the struct for this entry
+ * @ptr:        the &struct list_head pointer.
+ * @type:       the type of the struct this is embedded in.
+ * @member:     the name of the list_head within the struct.
+ *
+ * This primitive may safely run concurrently with the _rcu list-mutation
+ * primitives such as list_add_rcu() as long as it's guarded by
+ * rcu_read_lock_sched().
+ * Can be used while tracing RCU.
+ */
+#define lttng_list_entry_rcu(ptr, type, member) \
+({ \
+       typeof(*ptr) __rcu *__ptr = (typeof(*ptr) __rcu __force *)ptr; \
+       container_of((typeof(ptr))lttng_rcu_dereference(__ptr), type, member); \
+})
+
+/**
+ * lttng_list_for_each_entry_rcu - iterate over rcu list of given type
+ * @pos:       the type * to use as a loop cursor.
+ * @head:      the head for your list.
+ * @member:    the name of the list_head within the struct.
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as list_add_rcu()
+ * as long as the traversal is guarded by rcu_read_lock_sched().
+ * Can be used while tracing RCU.
+ */
+#define lttng_list_for_each_entry_rcu(pos, head, member) \
+       for (pos = lttng_list_entry_rcu((head)->next, typeof(*pos), member); \
+               &pos->member != (head); \
+               pos = lttng_list_entry_rcu(pos->member.next, typeof(*pos), member))
+
+/**
+ * lttng_hlist_for_each_entry_rcu - iterate over rcu list of given type (for tracing)
+ * @pos:       the type * to use as a loop cursor.
+ * @head:      the head for your list.
+ * @member:    the name of the hlist_node within the struct.
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as hlist_add_head_rcu()
+ * as long as the traversal is guarded by rcu_read_lock().
+ *
+ * This is the same as hlist_for_each_entry_rcu() except that it does
+ * not do any RCU debugging or tracing.
+ */
+#define lttng_hlist_for_each_entry_rcu(pos, head, member)      \
+       for (pos = lttng_hlist_entry_safe (lttng_rcu_dereference(hlist_first_rcu(head)), \
+                       typeof(*(pos)), member);                \
+               pos;                                            \
+               pos = lttng_hlist_entry_safe(lttng_rcu_dereference(hlist_next_rcu( \
+                       &(pos)->member)), typeof(*(pos)), member))
+
+#endif /* _LTTNG_WRAPPER_RCU_H */