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authorJosh Triplett <josht@us.ibm.com>2006-10-04 02:17:12 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-10-04 07:55:31 -0700
commit75cfef32f26d03f5d0a0833572d52f94ad858a36 (patch)
tree2440ee021888c4d743cf403a75d859060127479b
parent2860aaba4dc87fa43c08724434b87a8650f3bff5 (diff)
downloadop-kernel-dev-75cfef32f26d03f5d0a0833572d52f94ad858a36.zip
op-kernel-dev-75cfef32f26d03f5d0a0833572d52f94ad858a36.tar.gz
[PATCH] rcu: Fix sign bug making rcu_random always return the same sequence
rcu_random uses a counter rrs_count to occasionally mix data from get_random_bytes into the state of its pseudorandom generator. However, the rrs_counter gets declared as an unsigned long, and rcu_random checks for --rrs_count < 0, so this code will never mix any real random data into the state, and will thus always return the same sequence of random numbers. Also, change the return value of rcu_random from long to unsigned long, to avoid potential issues caused by the use of the % operator, which can return negative values for negative left operands. Signed-off-by: Josh Triplett <josh@freedesktop.org> Acked-by: Paul E. McKenney <paulmck@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--kernel/rcutorture.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 42e7f01..43d6d4f 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -147,7 +147,7 @@ rcu_torture_free(struct rcu_torture *p)
struct rcu_random_state {
unsigned long rrs_state;
- unsigned long rrs_count;
+ long rrs_count;
};
#define RCU_RANDOM_MULT 39916801 /* prime */
@@ -160,7 +160,7 @@ struct rcu_random_state {
* Crude but fast random-number generator. Uses a linear congruential
* generator, with occasional help from get_random_bytes().
*/
-static long
+static unsigned long
rcu_random(struct rcu_random_state *rrsp)
{
long refresh;
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