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-rw-r--r--drivers/char/random.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index d3bb7927fb49..914b1575df8f 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -250,6 +250,7 @@
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
+#include <linux/kthread.h>
#include <linux/percpu.h>
#include <linux/cryptohash.h>
#include <linux/fips.h>
@@ -1750,3 +1751,23 @@ randomize_range(unsigned long start, unsigned long end, unsigned long len)
return 0;
return PAGE_ALIGN(get_random_int() % range + start);
}
+
+/* Interface for in-kernel drivers of true hardware RNGs.
+ * Those devices may produce endless random bits and will be throttled
+ * when our pool is full.
+ */
+void add_hwgenerator_randomness(const char *buffer, size_t count,
+ size_t entropy)
+{
+ struct entropy_store *poolp = &input_pool;
+
+ /* Suspend writing if we're above the trickle threshold.
+ * We'll be woken up again once below random_write_wakeup_thresh,
+ * or when the calling thread is about to terminate.
+ */
+ wait_event_interruptible(random_write_wait, kthread_should_stop() ||
+ ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);
+ mix_pool_bytes(poolp, buffer, count);
+ credit_entropy_bits(poolp, entropy);
+}
+EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);