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Date: Fri, 20 Jan 2017 11:44:47 +0900
From: Namhyung Kim <namhyung@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 3/3] ftrace: Convert graph filter to use hash tables
Use ftrace_hash instead of a static array of a fixed size. This is
useful when a graph filter pattern matches to a large number of
functions. Now hash lookup is done with preemption disabled to protect
from the hash being changed/freed.
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
kernel/trace/ftrace.c | 190 +++++++++++++++++++++++++++++++++-----------------
kernel/trace/trace.h | 64 ++++++++---------
2 files changed, 158 insertions(+), 96 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 0470e373b9b4..2d554a02241d 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4378,7 +4378,7 @@ __setup("ftrace_filter=", set_ftrace_filter);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static char ftrace_graph_buf[FTRACE_FILTER_SIZE] __initdata;
static char ftrace_graph_notrace_buf[FTRACE_FILTER_SIZE] __initdata;
-static int ftrace_set_func(unsigned long *array, int *idx, int size, char *buffer);
+static int ftrace_graph_set_hash(struct ftrace_hash *hash, char *buffer);
static unsigned long save_global_trampoline;
static unsigned long save_global_flags;
@@ -4401,18 +4401,17 @@ static void __init set_ftrace_early_graph(char *buf, int enable)
{
int ret;
char *func;
- unsigned long *table = ftrace_graph_funcs;
- int *count = &ftrace_graph_count;
+ struct ftrace_hash *hash;
- if (!enable) {
- table = ftrace_graph_notrace_funcs;
- count = &ftrace_graph_notrace_count;
- }
+ if (enable)
+ hash = ftrace_graph_hash;
+ else
+ hash = ftrace_graph_notrace_hash;
while (buf) {
func = strsep(&buf, ",");
/* we allow only one expression at a time */
- ret = ftrace_set_func(table, count, FTRACE_GRAPH_MAX_FUNCS, func);
+ ret = ftrace_graph_set_hash(hash, func);
if (ret)
printk(KERN_DEBUG "ftrace: function %s not "
"traceable\n", func);
@@ -4536,15 +4535,20 @@ static const struct file_operations ftrace_notrace_fops = {
static DEFINE_MUTEX(graph_lock);
-int ftrace_graph_count;
-int ftrace_graph_notrace_count;
-unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;
-unsigned long ftrace_graph_notrace_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;
+struct ftrace_hash *ftrace_graph_hash = EMPTY_HASH;
+struct ftrace_hash *ftrace_graph_notrace_hash = EMPTY_HASH;
+
+enum graph_filter_type {
+ GRAPH_FILTER_NOTRACE = 0,
+ GRAPH_FILTER_FUNCTION,
+};
struct ftrace_graph_data {
- unsigned long *table;
- size_t size;
- int *count;
+ struct ftrace_hash *hash;
+ struct ftrace_func_entry *entry;
+ int idx; /* for hash table iteration */
+ enum graph_filter_type type;
+ struct ftrace_hash *new_hash;
const struct seq_operations *seq_ops;
};
@@ -4552,10 +4556,31 @@ static void *
__g_next(struct seq_file *m, loff_t *pos)
{
struct ftrace_graph_data *fgd = m->private;
+ struct ftrace_func_entry *entry = fgd->entry;
+ struct hlist_head *head;
+ int i, idx = fgd->idx;
- if (*pos >= *fgd->count)
+ if (*pos >= fgd->hash->count)
return NULL;
- return &fgd->table[*pos];
+
+ if (entry) {
+ hlist_for_each_entry_continue(entry, hlist) {
+ fgd->entry = entry;
+ return entry;
+ }
+
+ idx++;
+ }
+
+ for (i = idx; i < 1 << fgd->hash->size_bits; i++) {
+ head = &fgd->hash->buckets[i];
+ hlist_for_each_entry(entry, head, hlist) {
+ fgd->entry = entry;
+ fgd->idx = i;
+ return entry;
+ }
+ }
+ return NULL;
}
static void *
@@ -4572,9 +4597,11 @@ static void *g_start(struct seq_file *m, loff_t *pos)
mutex_lock(&graph_lock);
/* Nothing, tell g_show to print all functions are enabled */
- if (!*fgd->count && !*pos)
+ if (ftrace_hash_empty(fgd->hash) && !*pos)
return (void *)1;
+ fgd->idx = 0;
+ fgd->entry = NULL;
return __g_next(m, pos);
}
@@ -4585,22 +4612,22 @@ static void g_stop(struct seq_file *m, void *p)
static int g_show(struct seq_file *m, void *v)
{
- unsigned long *ptr = v;
+ struct ftrace_func_entry *entry = v;
- if (!ptr)
+ if (!entry)
return 0;
- if (ptr == (unsigned long *)1) {
+ if (entry == (void *)1) {
struct ftrace_graph_data *fgd = m->private;
- if (fgd->table == ftrace_graph_funcs)
+ if (fgd->type == GRAPH_FILTER_FUNCTION)
seq_puts(m, "#### all functions enabled ####\n");
else
seq_puts(m, "#### no functions disabled ####\n");
return 0;
}
- seq_printf(m, "%ps\n", (void *)*ptr);
+ seq_printf(m, "%ps\n", (void *)entry->ip);
return 0;
}
@@ -4617,24 +4644,37 @@ __ftrace_graph_open(struct inode *inode, struct file *file,
struct ftrace_graph_data *fgd)
{
int ret = 0;
+ struct ftrace_hash *new_hash = NULL;
- mutex_lock(&graph_lock);
- if ((file->f_mode & FMODE_WRITE) &&
- (file->f_flags & O_TRUNC)) {
- *fgd->count = 0;
- memset(fgd->table, 0, fgd->size * sizeof(*fgd->table));
+ if (file->f_mode & FMODE_WRITE) {
+ const int size_bits = FTRACE_HASH_DEFAULT_BITS;
+
+ if (file->f_flags & O_TRUNC)
+ new_hash = alloc_ftrace_hash(size_bits);
+ else
+ new_hash = alloc_and_copy_ftrace_hash(size_bits,
+ fgd->hash);
+ if (!new_hash) {
+ ret = -ENOMEM;
+ goto out;
+ }
}
- mutex_unlock(&graph_lock);
if (file->f_mode & FMODE_READ) {
- ret = seq_open(file, fgd->seq_ops);
+ ret = seq_open(file, &ftrace_graph_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = fgd;
+ } else {
+ /* Failed */
+ free_ftrace_hash(new_hash);
+ new_hash = NULL;
}
} else
file->private_data = fgd;
+out:
+ fgd->new_hash = new_hash;
return ret;
}
@@ -4642,6 +4682,7 @@ static int
ftrace_graph_open(struct inode *inode, struct file *file)
{
struct ftrace_graph_data *fgd;
+ int ret;
if (unlikely(ftrace_disabled))
return -ENODEV;
@@ -4650,18 +4691,25 @@ ftrace_graph_open(struct inode *inode, struct file *file)
if (fgd == NULL)
return -ENOMEM;
- fgd->table = ftrace_graph_funcs;
- fgd->size = FTRACE_GRAPH_MAX_FUNCS;
- fgd->count = &ftrace_graph_count;
+ mutex_lock(&graph_lock);
+
+ fgd->hash = ftrace_graph_hash;
+ fgd->type = GRAPH_FILTER_FUNCTION;
fgd->seq_ops = &ftrace_graph_seq_ops;
- return __ftrace_graph_open(inode, file, fgd);
+ ret = __ftrace_graph_open(inode, file, fgd);
+ if (ret < 0)
+ kfree(fgd);
+
+ mutex_unlock(&graph_lock);
+ return ret;
}
static int
ftrace_graph_notrace_open(struct inode *inode, struct file *file)
{
struct ftrace_graph_data *fgd;
+ int ret;
if (unlikely(ftrace_disabled))
return -ENODEV;
@@ -4670,45 +4718,53 @@ ftrace_graph_notrace_open(struct inode *inode, struct file *file)
if (fgd == NULL)
return -ENOMEM;
- fgd->table = ftrace_graph_notrace_funcs;
- fgd->size = FTRACE_GRAPH_MAX_FUNCS;
- fgd->count = &ftrace_graph_notrace_count;
+ mutex_lock(&graph_lock);
+
+ fgd->hash = ftrace_graph_notrace_hash;
+ fgd->type = GRAPH_FILTER_NOTRACE;
fgd->seq_ops = &ftrace_graph_seq_ops;
- return __ftrace_graph_open(inode, file, fgd);
+ ret = __ftrace_graph_open(inode, file, fgd);
+ if (ret < 0)
+ kfree(fgd);
+
+ mutex_unlock(&graph_lock);
+ return ret;
}
static int
ftrace_graph_release(struct inode *inode, struct file *file)
{
+ struct ftrace_graph_data *fgd;
+
if (file->f_mode & FMODE_READ) {
struct seq_file *m = file->private_data;
- kfree(m->private);
+ fgd = m->private;
seq_release(inode, file);
} else {
- kfree(file->private_data);
+ fgd = file->private_data;
}
+ kfree(fgd->new_hash);
+ kfree(fgd);
+
return 0;
}
static int
-ftrace_set_func(unsigned long *array, int *idx, int size, char *buffer)
+ftrace_graph_set_hash(struct ftrace_hash *hash, char *buffer)
{
struct ftrace_glob func_g;
struct dyn_ftrace *rec;
struct ftrace_page *pg;
+ struct ftrace_func_entry *entry;
int fail = 1;
int not;
- bool exists;
- int i;
/* decode regex */
func_g.type = filter_parse_regex(buffer, strlen(buffer),
&func_g.search, ¬);
- if (!not && *idx >= size)
- return -EBUSY;
func_g.len = strlen(func_g.search);
@@ -4725,26 +4781,18 @@ ftrace_set_func(unsigned long *array, int *idx, int size, char *buffer)
continue;
if (ftrace_match_record(rec, &func_g, NULL, 0)) {
- /* if it is in the array */
- exists = false;
- for (i = 0; i < *idx; i++) {
- if (array[i] == rec->ip) {
- exists = true;
- break;
- }
- }
+ entry = ftrace_lookup_ip(hash, rec->ip);
if (!not) {
fail = 0;
- if (!exists) {
- array[(*idx)++] = rec->ip;
- if (*idx >= size)
- goto out;
- }
+
+ if (entry)
+ continue;
+ if (add_hash_entry(hash, rec->ip) < 0)
+ goto out;
} else {
- if (exists) {
- array[i] = array[--(*idx)];
- array[*idx] = 0;
+ if (entry) {
+ free_hash_entry(hash, entry);
fail = 0;
}
}
@@ -4766,6 +4814,7 @@ ftrace_graph_write(struct file *file, const char __user *ubuf,
struct trace_parser parser;
ssize_t read, ret = 0;
struct ftrace_graph_data *fgd = file->private_data;
+ struct ftrace_hash *old_hash, *new_hash;
if (!cnt)
return 0;
@@ -4781,10 +4830,25 @@ ftrace_graph_write(struct file *file, const char __user *ubuf,
mutex_lock(&graph_lock);
/* we allow only one expression at a time */
- ret = ftrace_set_func(fgd->table, fgd->count, fgd->size,
- parser.buffer);
+ ret = ftrace_graph_set_hash(fgd->new_hash,
+ parser.buffer);
+
+ old_hash = fgd->hash;
+ new_hash = __ftrace_hash_move(fgd->new_hash);
+ if (!new_hash)
+ ret = -ENOMEM;
+
+ if (fgd->type == GRAPH_FILTER_FUNCTION)
+ rcu_assign_pointer(ftrace_graph_hash, new_hash);
+ else
+ rcu_assign_pointer(ftrace_graph_notrace_hash, new_hash);
mutex_unlock(&graph_lock);
+
+ /* Wait till all users are no longer using the old hash */
+ synchronize_sched();
+
+ free_ftrace_hash(old_hash);
}
if (!ret)
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 431a39ba8eee..ff39e92bacc7 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -803,51 +803,49 @@ static bool __always_inline ftrace_hash_empty(struct ftrace_hash *hash)
}
#ifdef CONFIG_DYNAMIC_FTRACE
-/* TODO: make this variable */
-#define FTRACE_GRAPH_MAX_FUNCS 32
-extern int ftrace_graph_count;
-extern unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS];
-extern int ftrace_graph_notrace_count;
-extern unsigned long ftrace_graph_notrace_funcs[FTRACE_GRAPH_MAX_FUNCS];
+extern struct ftrace_hash *ftrace_graph_hash;
+extern struct ftrace_hash *ftrace_graph_notrace_hash;
static inline int ftrace_graph_addr(unsigned long addr)
{
- int i;
-
- if (!ftrace_graph_count)
- return 1;
-
- for (i = 0; i < ftrace_graph_count; i++) {
- if (addr == ftrace_graph_funcs[i]) {
- /*
- * If no irqs are to be traced, but a set_graph_function
- * is set, and called by an interrupt handler, we still
- * want to trace it.
- */
- if (in_irq())
- trace_recursion_set(TRACE_IRQ_BIT);
- else
- trace_recursion_clear(TRACE_IRQ_BIT);
- return 1;
- }
+ int ret = 0;
+
+ preempt_disable_notrace();
+
+ if (ftrace_hash_empty(ftrace_graph_hash)) {
+ ret = 1;
+ goto out;
}
- return 0;
+ if (ftrace_lookup_ip(ftrace_graph_hash, addr)) {
+ /*
+ * If no irqs are to be traced, but a set_graph_function
+ * is set, and called by an interrupt handler, we still
+ * want to trace it.
+ */
+ if (in_irq())
+ trace_recursion_set(TRACE_IRQ_BIT);
+ else
+ trace_recursion_clear(TRACE_IRQ_BIT);
+ ret = 1;
+ }
+
+out:
+ preempt_enable_notrace();
+ return ret;
}
static inline int ftrace_graph_notrace_addr(unsigned long addr)
{
- int i;
+ int ret = 0;
- if (!ftrace_graph_notrace_count)
- return 0;
+ preempt_disable_notrace();
- for (i = 0; i < ftrace_graph_notrace_count; i++) {
- if (addr == ftrace_graph_notrace_funcs[i])
- return 1;
- }
+ if (ftrace_lookup_ip(ftrace_graph_notrace_hash, addr))
+ ret = 1;
- return 0;
+ preempt_enable_notrace();
+ return ret;
}
#else
static inline int ftrace_graph_addr(unsigned long addr)
--
2.11.0
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