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authorTorsten Duwe <duwe@lst.de>2014-06-14 23:48:41 -0400
committerTheodore Ts'o <tytso@mit.edu>2014-07-15 04:49:40 -0400
commit0f734e6e768b4b66737b3d3e13f1769a12ecff86 (patch)
tree637eb77455b97fa9385a442a25406443a6bceda7 /drivers/char
parentbe4000bc4644d027c519b6361f5ae3bbfc52c347 (diff)
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hwrng: add per-device entropy derating
This patch introduces a derating factor to struct hwrng for the random bits going into the kernel input pool, and a common default derating for drivers which do not specify one. Signed-off-by: Torsten Duwe <duwe@suse.de> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Acked-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/hw_random/core.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 48b3c812b9ec..3aaf97c774f1 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -56,11 +56,15 @@ static LIST_HEAD(rng_list);
static DEFINE_MUTEX(rng_mutex);
static int data_avail;
static u8 *rng_buffer, *rng_fillbuf;
-static unsigned short current_quality = 700; /* an arbitrary 70% */
+static unsigned short current_quality;
+static unsigned short default_quality; /* = 0; default to "off" */
module_param(current_quality, ushort, 0644);
MODULE_PARM_DESC(current_quality,
"current hwrng entropy estimation per mill");
+module_param(default_quality, ushort, 0644);
+MODULE_PARM_DESC(default_quality,
+ "default entropy content of hwrng per mill");
static void start_khwrngd(void);
@@ -79,6 +83,11 @@ static inline int hwrng_init(struct hwrng *rng)
return err;
}
+ current_quality = rng->quality ? : default_quality;
+ current_quality &= 1023;
+
+ if (current_quality == 0 && hwrng_fill)
+ kthread_stop(hwrng_fill);
if (current_quality > 0 && !hwrng_fill)
start_khwrngd();