1 files changed, 43 insertions, 33 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a141d8499ab0..4d90c916b2bb 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -401,6 +401,8 @@ static void ftrace_profile_reset(struct ftrace_profile_stat *stat)
 int ftrace_profile_pages_init(struct ftrace_profile_stat *stat)
 {
         struct ftrace_profile_page *pg;
+        int functions;
+        int pages;
         int i;
 
         /* If we already allocated, do nothing */
@@ -411,22 +413,46 @@ int ftrace_profile_pages_init(struct ftrace_profile_stat *stat)
         if (!stat->pages)
                 return -ENOMEM;
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+        functions = ftrace_update_tot_cnt;
+#else
+        /*
+         * We do not know the number of functions that exist because
+         * dynamic tracing is what counts them. With past experience
+         * we have around 20K functions. That should be more than enough.
+         * It is highly unlikely we will execute every function in
+         * the kernel.
+         */
+        functions = 20000;
+#endif
+
         pg = stat->start = stat->pages;
 
-        /* allocate 10 more pages to start */
-        for (i = 0; i < 10; i++) {
+        pages = DIV_ROUND_UP(functions, PROFILES_PER_PAGE);
+
+        for (i = 0; i < pages; i++) {
                 pg->next = (void *)get_zeroed_page(GFP_KERNEL);
-                /*
-                 * We only care about allocating profile_pages, if
-                 * we failed to allocate here, hopefully we will allocate
-                 * later.
-                 */
                 if (!pg->next)
-                        break;
+                        goto out_free;
                 pg = pg->next;
         }
 
         return 0;
+
+ out_free:
+        pg = stat->start;
+        while (pg) {
+                unsigned long tmp = (unsigned long)pg;
+
+                pg = pg->next;
+                free_page(tmp);
+        }
+
+        free_page((unsigned long)stat->pages);
+        stat->pages = NULL;
+        stat->start = NULL;
+
+        return -ENOMEM;
 }
 
 static int ftrace_profile_init_cpu(int cpu)
@@ -460,7 +486,7 @@ static int ftrace_profile_init_cpu(int cpu)
                         ftrace_profile_bits++;
         }
 
-        /* Preallocate a few pages */
+        /* Preallocate the function profiling pages */
         if (ftrace_profile_pages_init(stat) < 0) {
                 kfree(stat->hash);
                 stat->hash = NULL;
@@ -516,24 +542,21 @@ static void ftrace_add_profile(struct ftrace_profile_stat *stat,
         hlist_add_head_rcu(&rec->node, &stat->hash[key]);
 }
 
-/* Interrupts must be disabled calling this */
+/*
+ * The memory is already allocated, this simply finds a new record to use.
+ */
 static struct ftrace_profile *
-ftrace_profile_alloc(struct ftrace_profile_stat *stat,
-                     unsigned long ip, bool alloc_safe)
+ftrace_profile_alloc(struct ftrace_profile_stat *stat, unsigned long ip)
 {
         struct ftrace_profile *rec = NULL;
 
-        /* prevent recursion */
+        /* prevent recursion (from NMIs) */
         if (atomic_inc_return(&stat->disabled) != 1)
                 goto out;
 
-        /* Try to always keep another page available */
-        if (!stat->pages->next && alloc_safe)
-                stat->pages->next = (void *)get_zeroed_page(GFP_ATOMIC);
-
         /*
-         * Try to find the function again since another
-         * task on another CPU could have added it
+         * Try to find the function again since an NMI
+         * could have added it
          */
         rec = ftrace_find_profiled_func(stat, ip);
         if (rec)
@@ -555,29 +578,16 @@ ftrace_profile_alloc(struct ftrace_profile_stat *stat,
         return rec;
 }
 
-/*
- * If we are not in an interrupt, or softirq and
- * and interrupts are disabled and preemption is not enabled
- * (not in a spinlock) then it should be safe to allocate memory.
- */
-static bool ftrace_safe_to_allocate(void)
-{
-        return !in_interrupt() && irqs_disabled() && !preempt_count();
-}
-
 static void
 function_profile_call(unsigned long ip, unsigned long parent_ip)
 {
         struct ftrace_profile_stat *stat;
         struct ftrace_profile *rec;
         unsigned long flags;
-        bool alloc_safe;
 
         if (!ftrace_profile_enabled)
                 return;
 
-        alloc_safe = ftrace_safe_to_allocate();
-
         local_irq_save(flags);
 
         stat = &__get_cpu_var(ftrace_profile_stats);
@@ -586,7 +596,7 @@ function_profile_call(unsigned long ip, unsigned long parent_ip)
 
         rec = ftrace_find_profiled_func(stat, ip);
         if (!rec) {
-                rec = ftrace_profile_alloc(stat, ip, alloc_safe);
+                rec = ftrace_profile_alloc(stat, ip);
                 if (!rec)
                         goto out;
         }