random: suppress spammy warnings about unseeded randomness

[karo-tx-linux.git] / drivers / char / random.c

diff --git a/drivers/char/random.c b/drivers/char/random.c
index fa5bbd5a7ca0fb589a7924b16fa7d96462260189..799d37981d9971142ebb35b6d2bee891f8aa6191 100644 (file)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -436,6 +436,7 @@ static void _extract_crng(struct crng_state *crng,
 static void _crng_backtrack_protect(struct crng_state *crng,
                                    __u8 tmp[CHACHA20_BLOCK_SIZE], int used);
 static void process_random_ready_list(void);
+static void _get_random_bytes(void *buf, int nbytes);
 
 /**********************************************************************
  *
@@ -776,7 +777,7 @@ static void crng_initialize(struct crng_state *crng)
                _extract_entropy(&input_pool, &crng->state[4],
                                 sizeof(__u32) * 12, 0);
        else
-               get_random_bytes(&crng->state[4], sizeof(__u32) * 12);
+               _get_random_bytes(&crng->state[4], sizeof(__u32) * 12);
        for (i = 4; i < 16; i++) {
                if (!arch_get_random_seed_long(&rv) &&
                    !arch_get_random_long(&rv))
@@ -1466,6 +1467,30 @@ static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
        return ret;
 }
 
+#define warn_unseeded_randomness(previous) \
+       _warn_unseeded_randomness(__func__, (void *) _RET_IP_, (previous))
+
+static void _warn_unseeded_randomness(const char *func_name, void *caller,
+                                     void **previous)
+{
+#ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM
+       const bool print_once = false;
+#else
+       static bool print_once __read_mostly;
+#endif
+
+       if (print_once ||
+           crng_ready() ||
+           (previous && (caller == READ_ONCE(*previous))))
+               return;
+       WRITE_ONCE(*previous, caller);
+#ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM
+       print_once = true;
+#endif
+       pr_notice("random: %s called from %pF with crng_init=%d\n",
+                 func_name, caller, crng_init);
+}
+
 /*
  * This function is the exported kernel interface.  It returns some
  * number of good random numbers, suitable for key generation, seeding
@@ -1476,15 +1501,10 @@ static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
  * wait_for_random_bytes() should be called and return 0 at least once
  * at any point prior.
  */
-void get_random_bytes(void *buf, int nbytes)
+static void _get_random_bytes(void *buf, int nbytes)
 {
        __u8 tmp[CHACHA20_BLOCK_SIZE];
 
-#ifdef CONFIG_WARN_UNSEEDED_RANDOM
-       if (!crng_ready())
-               printk(KERN_NOTICE "random: %pF get_random_bytes called "
-                      "with crng_init = %d\n", (void *) _RET_IP_, crng_init);
-#endif
        trace_get_random_bytes(nbytes, _RET_IP_);
 
        while (nbytes >= CHACHA20_BLOCK_SIZE) {
@@ -1501,6 +1521,14 @@ void get_random_bytes(void *buf, int nbytes)
                crng_backtrack_protect(tmp, CHACHA20_BLOCK_SIZE);
        memzero_explicit(tmp, sizeof(tmp));
 }
+
+void get_random_bytes(void *buf, int nbytes)
+{
+       static void *previous;
+
+       warn_unseeded_randomness(&previous);
+       _get_random_bytes(buf, nbytes);
+}
 EXPORT_SYMBOL(get_random_bytes);
 
 /*
@@ -2064,6 +2092,7 @@ u64 get_random_u64(void)
        bool use_lock = READ_ONCE(crng_init) < 2;
        unsigned long flags = 0;
        struct batched_entropy *batch;
+       static void *previous;
 
 #if BITS_PER_LONG == 64
        if (arch_get_random_long((unsigned long *)&ret))
@@ -2074,11 +2103,7 @@ u64 get_random_u64(void)
            return ret;
 #endif
 
-#ifdef CONFIG_WARN_UNSEEDED_RANDOM
-       if (!crng_ready())
-               printk(KERN_NOTICE "random: %pF get_random_u64 called "
-                      "with crng_init = %d\n", (void *) _RET_IP_, crng_init);
-#endif
+       warn_unseeded_randomness(&previous);
 
        batch = &get_cpu_var(batched_entropy_u64);
        if (use_lock)
@@ -2102,15 +2127,12 @@ u32 get_random_u32(void)
        bool use_lock = READ_ONCE(crng_init) < 2;
        unsigned long flags = 0;
        struct batched_entropy *batch;
+       static void *previous;
 
        if (arch_get_random_int(&ret))
                return ret;
 
-#ifdef CONFIG_WARN_UNSEEDED_RANDOM
-       if (!crng_ready())
-               printk(KERN_NOTICE "random: %pF get_random_u32 called "
-                      "with crng_init = %d\n", (void *) _RET_IP_, crng_init);
-#endif
+       warn_unseeded_randomness(&previous);
 
        batch = &get_cpu_var(batched_entropy_u32);
        if (use_lock)