3 files changed, 38 insertions, 216 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 1c4835f86911..703eb53cfa2b 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -44,8 +44,6 @@ static inline void ftrace_kill(void) { }
 #endif /* CONFIG_FUNCTION_TRACER */
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-# define FTRACE_HASHBITS        10
-# define FTRACE_HASHSIZE        (1<<FTRACE_HASHBITS)
 
 enum {
         FTRACE_FL_FREE          = (1 << 0),
@@ -58,9 +56,9 @@ enum {
 };
 
 struct dyn_ftrace {
-        struct hlist_node node;
-        unsigned long     ip; /* address of mcount call-site */
-        unsigned long     flags;
+        struct list_head        list;
+        unsigned long           ip; /* address of mcount call-site */
+        unsigned long           flags;
 };
 
 int ftrace_force_update(void);
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 226fd9132d53..07762c08a944 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -25,7 +25,6 @@
 #include <linux/ftrace.h>
 #include <linux/sysctl.h>
 #include <linux/ctype.h>
-#include <linux/hash.h>
 #include <linux/list.h>
 
 #include <asm/ftrace.h>
@@ -189,9 +188,7 @@ static int ftrace_filtered;
 static int tracing_on;
 static int frozen_record_count;
 
-static struct hlist_head ftrace_hash[FTRACE_HASHSIZE];
-
-static DEFINE_PER_CPU(int, ftrace_shutdown_disable_cpu);
+static LIST_HEAD(ftrace_new_addrs);
 
 static DEFINE_MUTEX(ftrace_regex_lock);
 
@@ -210,8 +207,6 @@ struct ftrace_page {
 static struct ftrace_page       *ftrace_pages_start;
 static struct ftrace_page       *ftrace_pages;
 
-static int ftrace_record_suspend;
-
 static struct dyn_ftrace *ftrace_free_records;
 
 
@@ -242,72 +237,6 @@ static inline int record_frozen(struct dyn_ftrace *rec)
 # define record_frozen(rec)                     ({ 0; })
 #endif /* CONFIG_KPROBES */
 
-int skip_trace(unsigned long ip)
-{
-        unsigned long fl;
-        struct dyn_ftrace *rec;
-        struct hlist_node *t;
-        struct hlist_head *head;
-
-        if (frozen_record_count == 0)
-                return 0;
-
-        head = &ftrace_hash[hash_long(ip, FTRACE_HASHBITS)];
-        hlist_for_each_entry_rcu(rec, t, head, node) {
-                if (rec->ip == ip) {
-                        if (record_frozen(rec)) {
-                                if (rec->flags & FTRACE_FL_FAILED)
-                                        return 1;
-
-                                if (!(rec->flags & FTRACE_FL_CONVERTED))
-                                        return 1;
-
-                                if (!tracing_on || !ftrace_enabled)
-                                        return 1;
-
-                                if (ftrace_filtered) {
-                                        fl = rec->flags & (FTRACE_FL_FILTER |
-                                                           FTRACE_FL_NOTRACE);
-                                        if (!fl || (fl & FTRACE_FL_NOTRACE))
-                                                return 1;
-                                }
-                        }
-                        break;
-                }
-        }
-
-        return 0;
-}
-
-static inline int
-ftrace_ip_in_hash(unsigned long ip, unsigned long key)
-{
-        struct dyn_ftrace *p;
-        struct hlist_node *t;
-        int found = 0;
-
-        hlist_for_each_entry_rcu(p, t, &ftrace_hash[key], node) {
-                if (p->ip == ip) {
-                        found = 1;
-                        break;
-                }
-        }
-
-        return found;
-}
-
-static inline void
-ftrace_add_hash(struct dyn_ftrace *node, unsigned long key)
-{
-        hlist_add_head_rcu(&node->node, &ftrace_hash[key]);
-}
-
-/* called from kstop_machine */
-static inline void ftrace_del_hash(struct dyn_ftrace *node)
-{
-        hlist_del(&node->node);
-}
-
 static void ftrace_free_rec(struct dyn_ftrace *rec)
 {
         rec->ip = (unsigned long)ftrace_free_records;
@@ -362,69 +291,36 @@ static struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
         }
 
         if (ftrace_pages->index == ENTRIES_PER_PAGE) {
-                if (!ftrace_pages->next)
-                        return NULL;
+                if (!ftrace_pages->next) {
+                        /* allocate another page */
+                        ftrace_pages->next =
+                                (void *)get_zeroed_page(GFP_KERNEL);
+                        if (!ftrace_pages->next)
+                                return NULL;
+                }
                 ftrace_pages = ftrace_pages->next;
         }
 
         return &ftrace_pages->records[ftrace_pages->index++];
 }
 
-static void
+static struct dyn_ftrace *
 ftrace_record_ip(unsigned long ip)
 {
-        struct dyn_ftrace *node;
-        unsigned long key;
-        int resched;
-        int cpu;
+        struct dyn_ftrace *rec;
 
         if (!ftrace_enabled || ftrace_disabled)
-                return;
-
-        resched = need_resched();
-        preempt_disable_notrace();
-
-        /*
-         * We simply need to protect against recursion.
-         * Use the the raw version of smp_processor_id and not
-         * __get_cpu_var which can call debug hooks that can
-         * cause a recursive crash here.
-         */
-        cpu = raw_smp_processor_id();
-        per_cpu(ftrace_shutdown_disable_cpu, cpu)++;
-        if (per_cpu(ftrace_shutdown_disable_cpu, cpu) != 1)
-                goto out;
-
-        if (unlikely(ftrace_record_suspend))
-                goto out;
-
-        key = hash_long(ip, FTRACE_HASHBITS);
-
-        FTRACE_WARN_ON_ONCE(key >= FTRACE_HASHSIZE);
-
-        if (ftrace_ip_in_hash(ip, key))
-                goto out;
-
-        /* This ip may have hit the hash before the lock */
-        if (ftrace_ip_in_hash(ip, key))
-                goto out;
-
-        node = ftrace_alloc_dyn_node(ip);
-        if (!node)
-                goto out;
+                return NULL;
 
-        node->ip = ip;
+        rec = ftrace_alloc_dyn_node(ip);
+        if (!rec)
+                return NULL;
 
-        ftrace_add_hash(node, key);
+        rec->ip = ip;
 
- out:
-        per_cpu(ftrace_shutdown_disable_cpu, cpu)--;
+        list_add(&rec->list, &ftrace_new_addrs);
 
-        /* prevent recursion with scheduler */
-        if (resched)
-                preempt_enable_no_resched_notrace();
-        else
-                preempt_enable_notrace();
+        return rec;
 }
 
 #define FTRACE_ADDR ((long)(ftrace_caller))
@@ -543,7 +439,6 @@ static void ftrace_replace_code(int enable)
                                 rec->flags |= FTRACE_FL_FAILED;
                                 if ((system_state == SYSTEM_BOOTING) ||
                                     !core_kernel_text(rec->ip)) {
-                                        ftrace_del_hash(rec);
                                         ftrace_free_rec(rec);
                                 }
                         }
@@ -551,15 +446,6 @@ static void ftrace_replace_code(int enable)
         }
 }
 
-static void ftrace_shutdown_replenish(void)
-{
-        if (ftrace_pages->next)
-                return;
-
-        /* allocate another page */
-        ftrace_pages->next = (void *)get_zeroed_page(GFP_KERNEL);
-}
-
 static void print_ip_ins(const char *fmt, unsigned char *p)
 {
         int i;
@@ -616,18 +502,11 @@ ftrace_code_disable(struct dyn_ftrace *rec)
         return 1;
 }
 
-static int ftrace_update_code(void *ignore);
-
 static int __ftrace_modify_code(void *data)
 {
         int *command = data;
 
         if (*command & FTRACE_ENABLE_CALLS) {
-                /*
-                 * Update any recorded ips now that we have the
-                 * machine stopped
-                 */
-                ftrace_update_code(NULL);
                 ftrace_replace_code(1);
                 tracing_on = 1;
         } else if (*command & FTRACE_DISABLE_CALLS) {
@@ -738,84 +617,34 @@ 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)
 {
-        int i, save_ftrace_enabled;
+        struct dyn_ftrace *p, *t;
         cycle_t start, stop;
-        struct dyn_ftrace *p;
-        struct hlist_node *t, *n;
-        struct hlist_head *head, temp_list;
-
-        /* Don't be recording funcs now */
-        ftrace_record_suspend++;
-        save_ftrace_enabled = ftrace_enabled;
-        ftrace_enabled = 0;
 
         start = ftrace_now(raw_smp_processor_id());
         ftrace_update_cnt = 0;
 
-        /* No locks needed, the machine is stopped! */
-        for (i = 0; i < FTRACE_HASHSIZE; i++) {
-                INIT_HLIST_HEAD(&temp_list);
-                head = &ftrace_hash[i];
+        list_for_each_entry_safe(p, t, &ftrace_new_addrs, list) {
 
-                /* all CPUS are stopped, we are safe to modify code */
-                hlist_for_each_entry_safe(p, t, n, head, node) {
-                        /* Skip over failed records which have not been
-                         * freed. */
-                        if (p->flags & FTRACE_FL_FAILED)
-                                continue;
+                /* If something went wrong, bail without enabling anything */
+                if (unlikely(ftrace_disabled))
+                        return -1;
 
-                        /* Unconverted records are always at the head of the
-                         * hash bucket. Once we encounter a converted record,
-                         * simply skip over to the next bucket. Saves ftraced
-                         * some processor cycles (ftrace does its bid for
-                         * global warming :-p ). */
-                        if (p->flags & (FTRACE_FL_CONVERTED))
-                                break;
+                list_del_init(&p->list);
 
-                        /* Ignore updates to this record's mcount site.
-                         * Reintroduce this record at the head of this
-                         * bucket to attempt to "convert" it again if
-                         * the kprobe on it is unregistered before the
-                         * next run. */
-                        if (get_kprobe((void *)p->ip)) {
-                                ftrace_del_hash(p);
-                                INIT_HLIST_NODE(&p->node);
-                                hlist_add_head(&p->node, &temp_list);
-                                freeze_record(p);
-                                continue;
-                        } else {
-                                unfreeze_record(p);
-                        }
-
-                        /* convert record (i.e, patch mcount-call with NOP) */
-                        if (ftrace_code_disable(p)) {
-                                p->flags |= FTRACE_FL_CONVERTED;
-                                ftrace_update_cnt++;
-                        } else {
-                                if ((system_state == SYSTEM_BOOTING) ||
-                                    !core_kernel_text(p->ip)) {
-                                        ftrace_del_hash(p);
-                                        ftrace_free_rec(p);
-                                }
-                        }
-                }
-
-                hlist_for_each_entry_safe(p, t, n, &temp_list, node) {
-                        hlist_del(&p->node);
-                        INIT_HLIST_NODE(&p->node);
-                        hlist_add_head(&p->node, head);
-                }
+                /* convert record (i.e, patch mcount-call with NOP) */
+                if (ftrace_code_disable(p)) {
+                        p->flags |= FTRACE_FL_CONVERTED;
+                        ftrace_update_cnt++;
+                } else
+                        ftrace_free_rec(p);
         }
 
         stop = ftrace_now(raw_smp_processor_id());
         ftrace_update_time = stop - start;
         ftrace_update_tot_cnt += ftrace_update_cnt;
 
-        ftrace_enabled = save_ftrace_enabled;
-        ftrace_record_suspend--;
-
         return 0;
 }
 
@@ -847,7 +676,7 @@ static int __init ftrace_dyn_table_alloc(unsigned long num_to_init)
         pg = ftrace_pages = ftrace_pages_start;
 
         cnt = num_to_init / ENTRIES_PER_PAGE;
-        pr_info("ftrace: allocating %ld hash entries in %d pages\n",
+        pr_info("ftrace: allocating %ld entries in %d pages\n",
                 num_to_init, cnt);
 
         for (i = 0; i < cnt; i++) {
@@ -1451,20 +1280,18 @@ static int ftrace_convert_nops(unsigned long *start,
         unsigned long addr;
         unsigned long flags;
 
+        mutex_lock(&ftrace_start_lock);
         p = start;
         while (p < end) {
                 addr = ftrace_call_adjust(*p++);
-                /* should not be called from interrupt context */
-                spin_lock(&ftrace_lock);
                 ftrace_record_ip(addr);
-                spin_unlock(&ftrace_lock);
-                ftrace_shutdown_replenish();
         }
 
-        /* p is ignored */
+        /* disable interrupts to prevent kstop machine */
         local_irq_save(flags);
-        ftrace_update_code(p);
+        ftrace_update_code();
         local_irq_restore(flags);
+        mutex_unlock(&ftrace_start_lock);
 
         return 0;
 }
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 333a5162149b..06951e229443 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -865,9 +865,6 @@ function_trace_call(unsigned long ip, unsigned long parent_ip)
         if (unlikely(!ftrace_function_enabled))
                 return;
 
-        if (skip_trace(ip))
-                return;
-
         pc = preempt_count();
         resched = need_resched();
         preempt_disable_notrace();