stackdepot: add stats counters exported via debugfs

[linux-2.6-microblaze.git] / lib / stackdepot.c

diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index a0be5d0..80a8ca2 100644 (file)
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -14,6 +14,7 @@
 
 #define pr_fmt(fmt) "stackdepot: " fmt
 
+#include <linux/debugfs.h>
 #include <linux/gfp.h>
 #include <linux/jhash.h>
 #include <linux/kernel.h>
@@ -115,6 +116,23 @@ static bool new_pool_required = true;
 /* Lock that protects the variables above. */
 static DEFINE_RWLOCK(pool_rwlock);
 
+/* Statistics counters for debugfs. */
+enum depot_counter_id {
+       DEPOT_COUNTER_ALLOCS,
+       DEPOT_COUNTER_FREES,
+       DEPOT_COUNTER_INUSE,
+       DEPOT_COUNTER_FREELIST_SIZE,
+       DEPOT_COUNTER_COUNT,
+};
+static long counters[DEPOT_COUNTER_COUNT];
+static const char *const counter_names[] = {
+       [DEPOT_COUNTER_ALLOCS]          = "allocations",
+       [DEPOT_COUNTER_FREES]           = "frees",
+       [DEPOT_COUNTER_INUSE]           = "in_use",
+       [DEPOT_COUNTER_FREELIST_SIZE]   = "freelist_size",
+};
+static_assert(ARRAY_SIZE(counter_names) == DEPOT_COUNTER_COUNT);
+
 static int __init disable_stack_depot(char *str)
 {
        return kstrtobool(str, &stack_depot_disabled);
@@ -277,6 +295,7 @@ static void depot_init_pool(void *pool)
                stack->handle.extra = 0;
 
                list_add(&stack->list, &free_stacks);
+               counters[DEPOT_COUNTER_FREELIST_SIZE]++;
        }
 
        /* Save reference to the pool to be used by depot_fetch_stack(). */
@@ -376,6 +395,7 @@ depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc)
        /* Get and unlink the first entry from the freelist. */
        stack = list_first_entry(&free_stacks, struct stack_record, list);
        list_del(&stack->list);
+       counters[DEPOT_COUNTER_FREELIST_SIZE]--;
 
        /* Limit number of saved frames to CONFIG_STACKDEPOT_MAX_FRAMES. */
        if (size > CONFIG_STACKDEPOT_MAX_FRAMES)
@@ -394,6 +414,8 @@ depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc)
         */
        kmsan_unpoison_memory(stack, DEPOT_STACK_RECORD_SIZE);
 
+       counters[DEPOT_COUNTER_ALLOCS]++;
+       counters[DEPOT_COUNTER_INUSE]++;
        return stack;
 }
 
@@ -426,6 +448,10 @@ static void depot_free_stack(struct stack_record *stack)
        lockdep_assert_held_write(&pool_rwlock);
 
        list_add(&stack->list, &free_stacks);
+
+       counters[DEPOT_COUNTER_FREELIST_SIZE]++;
+       counters[DEPOT_COUNTER_FREES]++;
+       counters[DEPOT_COUNTER_INUSE]--;
 }
 
 /* Calculates the hash for a stack. */
@@ -690,3 +716,30 @@ unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle)
        return parts.extra;
 }
 EXPORT_SYMBOL(stack_depot_get_extra_bits);
+
+static int stats_show(struct seq_file *seq, void *v)
+{
+       /*
+        * data race ok: These are just statistics counters, and approximate
+        * statistics are ok for debugging.
+        */
+       seq_printf(seq, "pools: %d\n", data_race(pools_num));
+       for (int i = 0; i < DEPOT_COUNTER_COUNT; i++)
+               seq_printf(seq, "%s: %ld\n", counter_names[i], data_race(counters[i]));
+
+       return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(stats);
+
+static int depot_debugfs_init(void)
+{
+       struct dentry *dir;
+
+       if (stack_depot_disabled)
+               return 0;
+
+       dir = debugfs_create_dir("stackdepot", NULL);
+       debugfs_create_file("stats", 0444, dir, NULL, &stats_fops);
+       return 0;
+}
+late_initcall(depot_debugfs_init);