ftrace: remove daemon

The ftrace daemon is complex and error prone.  This patch strips it out
of the code.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 28 insertions, 294 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index b08996ca561d..e758cab0836f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -165,25 +165,8 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-
 #ifndef CONFIG_FTRACE_MCOUNT_RECORD
-/*
- * The hash lock is only needed when the recording of the mcount
- * callers are dynamic. That is, by the caller themselves and
- * not recorded via the compilation.
- */
-static DEFINE_SPINLOCK(ftrace_hash_lock);
-#define ftrace_hash_lock(flags)   spin_lock_irqsave(&ftrace_hash_lock, flags)
-#define ftrace_hash_unlock(flags) \
-                        spin_unlock_irqrestore(&ftrace_hash_lock, flags)
-static void ftrace_release_hash(unsigned long start, unsigned long end);
-#else
-/* This is protected via the ftrace_lock with MCOUNT_RECORD. */
-#define ftrace_hash_lock(flags)   do { (void)(flags); } while (0)
-#define ftrace_hash_unlock(flags) do { } while(0)
-static inline void ftrace_release_hash(unsigned long start, unsigned long end)
-{
-}
+# error Dynamic ftrace depends on MCOUNT_RECORD
 #endif
 
 /*
@@ -194,8 +177,6 @@ static inline void ftrace_release_hash(unsigned long start, unsigned long end)
  */
 static unsigned long mcount_addr = MCOUNT_ADDR;
 
-static struct task_struct *ftraced_task;
-
 enum {
         FTRACE_ENABLE_CALLS             = (1 << 0),
         FTRACE_DISABLE_CALLS            = (1 << 1),
@@ -212,7 +193,6 @@ static struct hlist_head ftrace_hash[FTRACE_HASHSIZE];
 
 static DEFINE_PER_CPU(int, ftrace_shutdown_disable_cpu);
 
-static DEFINE_MUTEX(ftraced_lock);
 static DEFINE_MUTEX(ftrace_regex_lock);
 
 struct ftrace_page {
@@ -230,10 +210,6 @@ struct ftrace_page {
 static struct ftrace_page       *ftrace_pages_start;
 static struct ftrace_page       *ftrace_pages;
 
-static int ftraced_trigger;
-static int ftraced_suspend;
-static int ftraced_stop;
-
 static int ftrace_record_suspend;
 
 static struct dyn_ftrace *ftrace_free_records;
@@ -398,7 +374,6 @@ static void
 ftrace_record_ip(unsigned long ip)
 {
         struct dyn_ftrace *node;
-        unsigned long flags;
         unsigned long key;
         int resched;
         int cpu;
@@ -430,24 +405,18 @@ ftrace_record_ip(unsigned long ip)
         if (ftrace_ip_in_hash(ip, key))
                 goto out;
 
-        ftrace_hash_lock(flags);
-
         /* This ip may have hit the hash before the lock */
         if (ftrace_ip_in_hash(ip, key))
-                goto out_unlock;
+                goto out;
 
         node = ftrace_alloc_dyn_node(ip);
         if (!node)
-                goto out_unlock;
+                goto out;
 
         node->ip = ip;
 
         ftrace_add_hash(node, key);
 
-        ftraced_trigger = 1;
-
- out_unlock:
-        ftrace_hash_unlock(flags);
  out:
         per_cpu(ftrace_shutdown_disable_cpu, cpu)--;
 
@@ -647,7 +616,7 @@ ftrace_code_disable(struct dyn_ftrace *rec)
         return 1;
 }
 
-static int __ftrace_update_code(void *ignore);
+static int ftrace_update_code(void *ignore);
 
 static int __ftrace_modify_code(void *data)
 {
@@ -659,7 +628,7 @@ static int __ftrace_modify_code(void *data)
                  * Update any recorded ips now that we have the
                  * machine stopped
                  */
-                __ftrace_update_code(NULL);
+                ftrace_update_code(NULL);
                 ftrace_replace_code(1);
                 tracing_on = 1;
         } else if (*command & FTRACE_DISABLE_CALLS) {
@@ -686,26 +655,9 @@ static void ftrace_run_update_code(int command)
         stop_machine(__ftrace_modify_code, &command, NULL);
 }
 
-void ftrace_disable_daemon(void)
-{
-        /* Stop the daemon from calling kstop_machine */
-        mutex_lock(&ftraced_lock);
-        ftraced_stop = 1;
-        mutex_unlock(&ftraced_lock);
-
-        ftrace_force_update();
-}
-
-void ftrace_enable_daemon(void)
-{
-        mutex_lock(&ftraced_lock);
-        ftraced_stop = 0;
-        mutex_unlock(&ftraced_lock);
-
-        ftrace_force_update();
-}
-
 static ftrace_func_t saved_ftrace_func;
+static int ftrace_start;
+static DEFINE_MUTEX(ftrace_start_lock);
 
 static void ftrace_startup(void)
 {
@@ -714,9 +666,9 @@ static void ftrace_startup(void)
         if (unlikely(ftrace_disabled))
                 return;
 
-        mutex_lock(&ftraced_lock);
-        ftraced_suspend++;
-        if (ftraced_suspend == 1)
+        mutex_lock(&ftrace_start_lock);
+        ftrace_start++;
+        if (ftrace_start == 1)
                 command |= FTRACE_ENABLE_CALLS;
 
         if (saved_ftrace_func != ftrace_trace_function) {
@@ -729,7 +681,7 @@ static void ftrace_startup(void)
 
         ftrace_run_update_code(command);
  out:
-        mutex_unlock(&ftraced_lock);
+        mutex_unlock(&ftrace_start_lock);
 }
 
 static void ftrace_shutdown(void)
@@ -739,9 +691,9 @@ static void ftrace_shutdown(void)
         if (unlikely(ftrace_disabled))
                 return;
 
-        mutex_lock(&ftraced_lock);
-        ftraced_suspend--;
-        if (!ftraced_suspend)
+        mutex_lock(&ftrace_start_lock);
+        ftrace_start--;
+        if (!ftrace_start)
                 command |= FTRACE_DISABLE_CALLS;
 
         if (saved_ftrace_func != ftrace_trace_function) {
@@ -754,7 +706,7 @@ static void ftrace_shutdown(void)
 
         ftrace_run_update_code(command);
  out:
-        mutex_unlock(&ftraced_lock);
+        mutex_unlock(&ftrace_start_lock);
 }
 
 static void ftrace_startup_sysctl(void)
@@ -764,15 +716,15 @@ static void ftrace_startup_sysctl(void)
         if (unlikely(ftrace_disabled))
                 return;
 
-        mutex_lock(&ftraced_lock);
+        mutex_lock(&ftrace_start_lock);
         /* Force update next time */
         saved_ftrace_func = NULL;
-        /* ftraced_suspend is true if we want ftrace running */
-        if (ftraced_suspend)
+        /* ftrace_start is true if we want ftrace running */
+        if (ftrace_start)
                 command |= FTRACE_ENABLE_CALLS;
 
         ftrace_run_update_code(command);
-        mutex_unlock(&ftraced_lock);
+        mutex_unlock(&ftrace_start_lock);
 }
 
 static void ftrace_shutdown_sysctl(void)
@@ -782,20 +734,20 @@ static void ftrace_shutdown_sysctl(void)
         if (unlikely(ftrace_disabled))
                 return;
 
-        mutex_lock(&ftraced_lock);
-        /* ftraced_suspend is true if ftrace is running */
-        if (ftraced_suspend)
+        mutex_lock(&ftrace_start_lock);
+        /* ftrace_start is true if ftrace is running */
+        if (ftrace_start)
                 command |= FTRACE_DISABLE_CALLS;
 
         ftrace_run_update_code(command);
-        mutex_unlock(&ftraced_lock);
+        mutex_unlock(&ftrace_start_lock);
 }
 
 static cycle_t          ftrace_update_time;
 static unsigned long    ftrace_update_cnt;
 unsigned long           ftrace_update_tot_cnt;
 
-static int __ftrace_update_code(void *ignore)
+static int ftrace_update_code(void *ignore)
 {
         int i, save_ftrace_enabled;
         cycle_t start, stop;
@@ -869,7 +821,6 @@ static int __ftrace_update_code(void *ignore)
         stop = ftrace_now(raw_smp_processor_id());
         ftrace_update_time = stop - start;
         ftrace_update_tot_cnt += ftrace_update_cnt;
-        ftraced_trigger = 0;
 
         ftrace_enabled = save_ftrace_enabled;
         ftrace_record_suspend--;
@@ -877,17 +828,6 @@ static int __ftrace_update_code(void *ignore)
         return 0;
 }
 
-static int ftrace_update_code(void)
-{
-        if (unlikely(ftrace_disabled) ||
-            !ftrace_enabled || !ftraced_trigger)
-                return 0;
-
-        stop_machine(__ftrace_update_code, NULL, NULL);
-
-        return 1;
-}
-
 static int __init ftrace_dyn_table_alloc(unsigned long num_to_init)
 {
         struct ftrace_page *pg;
@@ -1425,10 +1365,10 @@ ftrace_regex_release(struct inode *inode, struct file *file, int enable)
         }
 
         mutex_lock(&ftrace_sysctl_lock);
-        mutex_lock(&ftraced_lock);
-        if (iter->filtered && ftraced_suspend && ftrace_enabled)
+        mutex_lock(&ftrace_start_lock);
+        if (iter->filtered && ftrace_start && ftrace_enabled)
                 ftrace_run_update_code(FTRACE_ENABLE_CALLS);
-        mutex_unlock(&ftraced_lock);
+        mutex_unlock(&ftrace_start_lock);
         mutex_unlock(&ftrace_sysctl_lock);
 
         kfree(iter);
@@ -1448,55 +1388,6 @@ ftrace_notrace_release(struct inode *inode, struct file *file)
         return ftrace_regex_release(inode, file, 0);
 }
 
-static ssize_t
-ftraced_read(struct file *filp, char __user *ubuf,
-                     size_t cnt, loff_t *ppos)
-{
-        /* don't worry about races */
-        char *buf = ftraced_stop ? "disabled\n" : "enabled\n";
-        int r = strlen(buf);
-
-        return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
-}
-
-static ssize_t
-ftraced_write(struct file *filp, const char __user *ubuf,
-                      size_t cnt, loff_t *ppos)
-{
-        char buf[64];
-        long val;
-        int ret;
-
-        if (cnt >= sizeof(buf))
-                return -EINVAL;
-
-        if (copy_from_user(&buf, ubuf, cnt))
-                return -EFAULT;
-
-        if (strncmp(buf, "enable", 6) == 0)
-                val = 1;
-        else if (strncmp(buf, "disable", 7) == 0)
-                val = 0;
-        else {
-                buf[cnt] = 0;
-
-                ret = strict_strtoul(buf, 10, &val);
-                if (ret < 0)
-                        return ret;
-
-                val = !!val;
-        }
-
-        if (val)
-                ftrace_enable_daemon();
-        else
-                ftrace_disable_daemon();
-
-        filp->f_pos += cnt;
-
-        return cnt;
-}
-
 static struct file_operations ftrace_avail_fops = {
         .open = ftrace_avail_open,
         .read = seq_read,
@@ -1527,38 +1418,6 @@ static struct file_operations ftrace_notrace_fops = {
         .release = ftrace_notrace_release,
 };
 
-static struct file_operations ftraced_fops = {
-        .open = tracing_open_generic,
-        .read = ftraced_read,
-        .write = ftraced_write,
-};
-
-/**
- * ftrace_force_update - force an update to all recording ftrace functions
- */
-int ftrace_force_update(void)
-{
-        int ret = 0;
-
-        if (unlikely(ftrace_disabled))
-                return -ENODEV;
-
-        mutex_lock(&ftrace_sysctl_lock);
-        mutex_lock(&ftraced_lock);
-
-        /*
-         * If ftraced_trigger is not set, then there is nothing
-         * to update.
-         */
-        if (ftraced_trigger && !ftrace_update_code())
-                ret = -EBUSY;
-
-        mutex_unlock(&ftraced_lock);
-        mutex_unlock(&ftrace_sysctl_lock);
-
-        return ret;
-}
-
 static __init int ftrace_init_debugfs(void)
 {
         struct dentry *d_tracer;
@@ -1589,17 +1448,11 @@ static __init int ftrace_init_debugfs(void)
                 pr_warning("Could not create debugfs "
                            "'set_ftrace_notrace' entry\n");
 
-        entry = debugfs_create_file("ftraced_enabled", 0644, d_tracer,
-                                    NULL, &ftraced_fops);
-        if (!entry)
-                pr_warning("Could not create debugfs "
-                           "'ftraced_enabled' entry\n");
         return 0;
 }
 
 fs_initcall(ftrace_init_debugfs);
 
-#ifdef CONFIG_FTRACE_MCOUNT_RECORD
 static int ftrace_convert_nops(unsigned long *start,
                                unsigned long *end)
 {
@@ -1619,7 +1472,7 @@ static int ftrace_convert_nops(unsigned long *start,
 
         /* p is ignored */
         local_irq_save(flags);
-        __ftrace_update_code(p);
+        ftrace_update_code(p);
         local_irq_restore(flags);
 
         return 0;
@@ -1666,122 +1519,6 @@ void __init ftrace_init(void)
  failed:
         ftrace_disabled = 1;
 }
-#else /* CONFIG_FTRACE_MCOUNT_RECORD */
-
-static void ftrace_release_hash(unsigned long start, unsigned long end)
-{
-        struct dyn_ftrace *rec;
-        struct hlist_node *t, *n;
-        struct hlist_head *head, temp_list;
-        unsigned long flags;
-        int i, cpu;
-
-        preempt_disable_notrace();
-
-        /* disable incase we call something that calls mcount */
-        cpu = raw_smp_processor_id();
-        per_cpu(ftrace_shutdown_disable_cpu, cpu)++;
-
-        ftrace_hash_lock(flags);
-
-        for (i = 0; i < FTRACE_HASHSIZE; i++) {
-                INIT_HLIST_HEAD(&temp_list);
-                head = &ftrace_hash[i];
-
-                /* all CPUS are stopped, we are safe to modify code */
-                hlist_for_each_entry_safe(rec, t, n, head, node) {
-                        if (rec->flags & FTRACE_FL_FREE)
-                                continue;
-
-                        if ((rec->ip >= start) && (rec->ip < end))
-                                ftrace_free_rec(rec);
-                }
-        }
-
-        ftrace_hash_unlock(flags);
-
-        per_cpu(ftrace_shutdown_disable_cpu, cpu)--;
-        preempt_enable_notrace();
-
-}
-
-static int ftraced(void *ignore)
-{
-        unsigned long usecs;
-
-        while (!kthread_should_stop()) {
-
-                set_current_state(TASK_INTERRUPTIBLE);
-
-                /* check once a second */
-                schedule_timeout(HZ);
-
-                if (unlikely(ftrace_disabled))
-                        continue;
-
-                mutex_lock(&ftrace_sysctl_lock);
-                mutex_lock(&ftraced_lock);
-                if (!ftraced_suspend && !ftraced_stop &&
-                    ftrace_update_code()) {
-                        usecs = nsecs_to_usecs(ftrace_update_time);
-                        if (ftrace_update_tot_cnt > 100000) {
-                                ftrace_update_tot_cnt = 0;
-                                pr_info("hm, dftrace overflow: %lu change%s"
-                                        " (%lu total) in %lu usec%s\n",
-                                        ftrace_update_cnt,
-                                        ftrace_update_cnt != 1 ? "s" : "",
-                                        ftrace_update_tot_cnt,
-                                        usecs, usecs != 1 ? "s" : "");
-                                FTRACE_WARN_ON_ONCE(1);
-                        }
-                }
-                mutex_unlock(&ftraced_lock);
-                mutex_unlock(&ftrace_sysctl_lock);
-
-                ftrace_shutdown_replenish();
-        }
-        __set_current_state(TASK_RUNNING);
-        return 0;
-}
-
-static int __init ftrace_dynamic_init(void)
-{
-        struct task_struct *p;
-        unsigned long addr;
-        int ret;
-
-        addr = (unsigned long)ftrace_record_ip;
-
-        stop_machine(ftrace_dyn_arch_init, &addr, NULL);
-
-        /* ftrace_dyn_arch_init places the return code in addr */
-        if (addr) {
-                ret = (int)addr;
-                goto failed;
-        }
-
-        ret = ftrace_dyn_table_alloc(NR_TO_INIT);
-        if (ret)
-                goto failed;
-
-        p = kthread_run(ftraced, NULL, "ftraced");
-        if (IS_ERR(p)) {
-                ret = -1;
-                goto failed;
-        }
-
-        last_ftrace_enabled = ftrace_enabled = 1;
-        ftraced_task = p;
-
-        return 0;
-
- failed:
-        ftrace_disabled = 1;
-        return ret;
-}
-
-core_initcall(ftrace_dynamic_init);
-#endif /* CONFIG_FTRACE_MCOUNT_RECORD */
 
 #else
 # define ftrace_startup()               do { } while (0)
@@ -1801,9 +1538,6 @@ void ftrace_kill(void)
 {
         ftrace_disabled = 1;
         ftrace_enabled = 0;
-#ifdef CONFIG_DYNAMIC_FTRACE
-        ftraced_suspend = -1;
-#endif
         clear_ftrace_function();
 }