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Three minor updates 

- Use of the new GFP_RETRY_MAYFAIL to be more aggressive in allocating
    memory for the ring buffer without causing OOMs
 
  - Fix a memory leak in adding and removing instances
 
  - Add __rcu annotation to be able to debug RCU usage of function
    tracing a bit better.
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Merge tag 'trace-v4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "Three minor updates

   - Use the new GFP_RETRY_MAYFAIL to be more aggressive in allocating
     memory for the ring buffer without causing OOMs

   - Fix a memory leak in adding and removing instances

   - Add __rcu annotation to be able to debug RCU usage of function
     tracing a bit better"

* tag 'trace-v4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  trace: fix the errors caused by incompatible type of RCU variables
  tracing: Fix kmemleak in instance_rmdir
  tracing/ring_buffer: Try harder to allocate
This commit is contained in:
Linus Torvalds 2017-07-21 13:59:51 -07:00
parent b0a752818b f86f418059
commit f79ec886f9
6 changed files with 40 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/ftrace.h
View File

@ -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;

2
include/linux/trace_events.h
View File

@ -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;

41
kernel/trace/ftrace.c
View File

@ -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();

10
kernel/trace/ring_buffer.c
View File

@ -1136,12 +1136,12 @@ static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu)
for (i = 0; i < nr_pages; i++) {
struct page *page;
/*
* __GFP_NORETRY flag makes sure that the allocation fails
* gracefully without invoking oom-killer and the system is
* not destabilized.
* __GFP_RETRY_MAYFAIL flag makes sure that the allocation fails
* gracefully without invoking oom-killer and the system is not
* destabilized.
*/
bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()),
GFP_KERNEL | __GFP_NORETRY,
GFP_KERNEL | __GFP_RETRY_MAYFAIL,
cpu_to_node(cpu));
if (!bpage)
goto free_pages;
@ -1149,7 +1149,7 @@ static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu)
list_add(&bpage->list, pages);
page = alloc_pages_node(cpu_to_node(cpu),
GFP_KERNEL | __GFP_NORETRY, 0);
GFP_KERNEL | __GFP_RETRY_MAYFAIL, 0);
if (!page)
goto free_pages;
bpage->page = page_address(page);

1
kernel/trace/trace.c
View File

@ -7774,6 +7774,7 @@ static int instance_rmdir(const char *name)
}
kfree(tr->topts);
free_cpumask_var(tr->tracing_cpumask);
kfree(tr->name);
kfree(tr);

6
kernel/trace/trace.h
View File

@ -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 {