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| author | Josh Triplett <josht@us.ibm.com> | 2006-10-04 02:17:12 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-04 07:55:31 -0700 |
| commit | 75cfef32f26d03f5d0a0833572d52f94ad858a36 (patch) | |
| tree | 2440ee021888c4d743cf403a75d859060127479b /kernel | |
| parent | 2860aaba4dc87fa43c08724434b87a8650f3bff5 (diff) | |
| download | linux-75cfef32f26d03f5d0a0833572d52f94ad858a36.tar.gz linux-75cfef32f26d03f5d0a0833572d52f94ad858a36.tar.bz2 linux-75cfef32f26d03f5d0a0833572d52f94ad858a36.zip | |
[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>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcutorture.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index 42e7f01e8003..43d6d4f9ef09 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; |