trace: fix the errors caused by incompatible type of RCU variables

The variables which are processed by RCU functions should be annotated
as RCU, otherwise sparse will report the errors like below:

"error: incompatible types in comparison expression (different
address spaces)"

Link: http://lkml.kernel.org/r/1496823171-7758-1-git-send-email-zhang.chunyan@linaro.org
Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
[ Updated to not be 100% 80 column strict ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 5857390ac35aa37d4d2431504adc98c3a3075026..6383115e9d2c5c6459973a1d2d74609aeb438b9f 100644 (file)
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -145,8 +145,8 @@ enum {
 #ifdef CONFIG_DYNAMIC_FTRACE
 /* The hash used to know what functions callbacks trace */
 struct ftrace_ops_hash {
-       struct ftrace_hash              *notrace_hash;
-       struct ftrace_hash              *filter_hash;
+       struct ftrace_hash __rcu        *notrace_hash;
+       struct ftrace_hash __rcu        *filter_hash;
        struct mutex                    regex_lock;
 };
 
@@ -168,7 +168,7 @@ static inline void ftrace_free_init_mem(void) { }
  */
 struct ftrace_ops {
        ftrace_func_t                   func;
-       struct ftrace_ops               *next;
+       struct ftrace_ops __rcu         *next;
        unsigned long                   flags;
        void                            *private;
        ftrace_func_t                   saved_func;

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index f73cedfa2e0b97cde1c3bcd1c07d650cf616afdb..536c80ff7ad96680ddcca0a7880cd7df81c57f17 100644 (file)
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -338,7 +338,7 @@ enum {
 struct trace_event_file {
        struct list_head                list;
        struct trace_event_call         *event_call;
-       struct event_filter             *filter;
+       struct event_filter __rcu       *filter;
        struct dentry                   *dir;
        struct trace_array              *tr;
        struct trace_subsystem_dir      *system;

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 53f6b6401cf05fe9d63be0b67d646d25eed929e7..02004ae918608f915b28341b6ed1b3b7f551c5a5 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -113,7 +113,7 @@ static int ftrace_disabled __read_mostly;
 
 static DEFINE_MUTEX(ftrace_lock);
 
-static struct ftrace_ops *ftrace_ops_list __read_mostly = &ftrace_list_end;
+static struct ftrace_ops __rcu *ftrace_ops_list __read_mostly = &ftrace_list_end;
 ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
 static struct ftrace_ops global_ops;
 
@@ -169,8 +169,11 @@ int ftrace_nr_registered_ops(void)
 
        mutex_lock(&ftrace_lock);
 
-       for (ops = ftrace_ops_list;
-            ops != &ftrace_list_end; ops = ops->next)
+       for (ops = rcu_dereference_protected(ftrace_ops_list,
+                                            lockdep_is_held(&ftrace_lock));
+            ops != &ftrace_list_end;
+            ops = rcu_dereference_protected(ops->next,
+                                            lockdep_is_held(&ftrace_lock)))
                cnt++;
 
        mutex_unlock(&ftrace_lock);
@@ -275,10 +278,11 @@ static void update_ftrace_function(void)
         * If there's only one ftrace_ops registered, the ftrace_ops_list
         * will point to the ops we want.
         */
-       set_function_trace_op = ftrace_ops_list;
+       set_function_trace_op = rcu_dereference_protected(ftrace_ops_list,
+                                               lockdep_is_held(&ftrace_lock));
 
        /* If there's no ftrace_ops registered, just call the stub function */
-       if (ftrace_ops_list == &ftrace_list_end) {
+       if (set_function_trace_op == &ftrace_list_end) {
                func = ftrace_stub;
 
        /*
@@ -286,7 +290,8 @@ static void update_ftrace_function(void)
         * recursion safe and not dynamic and the arch supports passing ops,
         * then have the mcount trampoline call the function directly.
         */
-       } else if (ftrace_ops_list->next == &ftrace_list_end) {
+       } else if (rcu_dereference_protected(ftrace_ops_list->next,
+                       lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) {
                func = ftrace_ops_get_list_func(ftrace_ops_list);
 
        } else {
@@ -348,9 +353,11 @@ int using_ftrace_ops_list_func(void)
        return ftrace_trace_function == ftrace_ops_list_func;
 }
 
-static void add_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
+static void add_ftrace_ops(struct ftrace_ops __rcu **list,
+                          struct ftrace_ops *ops)
 {
-       ops->next = *list;
+       rcu_assign_pointer(ops->next, *list);
+
        /*
         * We are entering ops into the list but another
         * CPU might be walking that list. We need to make sure
@@ -360,7 +367,8 @@ static void add_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
        rcu_assign_pointer(*list, ops);
 }
 
-static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
+static int remove_ftrace_ops(struct ftrace_ops __rcu **list,
+                            struct ftrace_ops *ops)
 {
        struct ftrace_ops **p;
 
@@ -368,7 +376,10 @@ static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
         * If we are removing the last function, then simply point
         * to the ftrace_stub.
         */
-       if (*list == ops && ops->next == &ftrace_list_end) {
+       if (rcu_dereference_protected(*list,
+                       lockdep_is_held(&ftrace_lock)) == ops &&
+           rcu_dereference_protected(ops->next,
+                       lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) {
                *list = &ftrace_list_end;
                return 0;
        }
@@ -1569,8 +1580,8 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs)
                return 0;
 #endif
 
-       hash.filter_hash = rcu_dereference_raw_notrace(ops->func_hash->filter_hash);
-       hash.notrace_hash = rcu_dereference_raw_notrace(ops->func_hash->notrace_hash);
+       rcu_assign_pointer(hash.filter_hash, ops->func_hash->filter_hash);
+       rcu_assign_pointer(hash.notrace_hash, ops->func_hash->notrace_hash);
 
        if (hash_contains_ip(ip, &hash))
                ret = 1;
@@ -2840,7 +2851,8 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command)
         * If there's no more ops registered with ftrace, run a
         * sanity check to make sure all rec flags are cleared.
         */
-       if (ftrace_ops_list == &ftrace_list_end) {
+       if (rcu_dereference_protected(ftrace_ops_list,
+                       lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) {
                struct ftrace_page *pg;
                struct dyn_ftrace *rec;
 
@@ -6453,7 +6465,8 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
        if (ftrace_enabled) {
 
                /* we are starting ftrace again */
-               if (ftrace_ops_list != &ftrace_list_end)
+               if (rcu_dereference_protected(ftrace_ops_list,
+                       lockdep_is_held(&ftrace_lock)) != &ftrace_list_end)
                        update_ftrace_function();
 
                ftrace_startup_sysctl();

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 6ade1c55cc3acaccaad5f50896708c1774072854..490ba229931d7d00243a1be009dec6ab2b3a5864 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1210,9 +1210,9 @@ struct ftrace_event_field {
 struct event_filter {
        int                     n_preds;        /* Number assigned */
        int                     a_preds;        /* allocated */
-       struct filter_pred      *preds;
-       struct filter_pred      *root;
-       char                    *filter_string;
+       struct filter_pred __rcu        *preds;
+       struct filter_pred __rcu        *root;
+       char                            *filter_string;
 };
 
 struct event_subsystem {