tracing: remove on the fly allocator from function profiler

[mv-sheeva.git] / kernel / trace / ftrace.c

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a141d8499ab0395d5620643b34d2fc66de61e725..4d90c916b2bbd75d8ba024a6da7f332a2e110a68 100644 (file)
--- 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;
        }