From ee1de406ba6eb1e01f143fe3351e70cc772cc63e Mon Sep 17 00:00:00 2001 From: Greg Price Date: Fri, 29 Nov 2013 15:56:16 -0500 Subject: random: simplify accounting logic This logic is exactly equivalent to the old logic, but it should be easier to see what it's doing. The equivalence depends on one fact from outside this function: when 'r->limit' is false, 'reserved' is zero. (Well, two facts; the other is that 'reserved' is never negative.) Cc: Jiri Kosina Cc: "H. Peter Anvin" Signed-off-by: Greg Price Signed-off-by: "Theodore Ts'o" diff --git a/drivers/char/random.c b/drivers/char/random.c index 2c532a6..9675821 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -984,14 +984,10 @@ retry: ibytes = 0; } else { /* If limited, never pull more than available */ - if (r->limit && ibytes + reserved >= have_bytes) - ibytes = have_bytes - reserved; - - if (have_bytes >= ibytes + reserved) - entropy_count -= ibytes << (ENTROPY_SHIFT + 3); - else - entropy_count = reserved << (ENTROPY_SHIFT + 3); - + if (r->limit) + ibytes = min_t(size_t, ibytes, have_bytes - reserved); + entropy_count = max_t(int, 0, + entropy_count - (ibytes << (ENTROPY_SHIFT + 3))); if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) goto retry; -- cgit v0.10.2