[PATCH v3 2/3] treewide: use get_random_u32_{above,below}() instead of manual loop

Jason A. Donenfeld
2022-11-17T20:30:47Z

These cases were done with this Coccinelle:

@@
expression E;
identifier I;
@@
- do {
... when != I
- I = get_random_u32();
... when != I
- } while (I > E);
+ I = get_random_u32_below(E + 1);

@@
expression E;
identifier I;
@@
- do {
... when != I
- I = get_random_u32();
... when != I
- } while (I >= E);
+ I = get_random_u32_below(E);

@@
expression E;
identifier I;
@@
- do {
... when != I
- I = get_random_u32();
... when != I
- } while (I < E);
+ I = get_random_u32_above(E - 1);

@@
expression E;
identifier I;
@@
- do {
... when != I
- I = get_random_u32();
... when != I
- } while (I <= E);
+ I = get_random_u32_above(E);

@@
identifier I;
@@
- do {
... when != I
- I = get_random_u32();
... when != I
- } while (!I);
+ I = get_random_u32_above(0);

@@
identifier I;
@@
- do {
... when != I
- I = get_random_u32();
... when != I
- } while (I == 0);
+ I = get_random_u32_above(0);

@@
expression E;
@@
- E + 1 + get_random_u32_below(U32_MAX - E)
+ get_random_u32_above(E)

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
fs/ext4/mmp.c | 8 +-------
lib/test_fprobe.c | 5 +----
lib/test_kprobes.c | 5 +----
net/ipv6/output_core.c | 8 +-------
net/vmw_vsock/af_vsock.c | 3 +--
5 files changed, 5 insertions(+), 24 deletions(-)

diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 588cb09c5291..4681fff6665f 100644
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c
@@ -262,13 +262,7 @@ void ext4_stop_mmpd(struct ext4_sb_info *sbi)
*/
static unsigned int mmp_new_seq(void)
{
- u32 new_seq;
-
- do {
- new_seq = get_random_u32();
- } while (new_seq > EXT4_MMP_SEQ_MAX);
-
- return new_seq;
+ return get_random_u32_below(EXT4_MMP_SEQ_MAX + 1);
}

/*
diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
index e0381b3ec410..1fb56cf5e5ce 100644
--- a/lib/test_fprobe.c
+++ b/lib/test_fprobe.c
@@ -144,10 +144,7 @@ static unsigned long get_ftrace_location(void *func)

static int fprobe_test_init(struct kunit *test)
{
- do {
- rand1 = get_random_u32();
- } while (rand1 <= div_factor);
-
+ rand1 = get_random_u32_above(div_factor);
target = fprobe_selftest_target;
target2 = fprobe_selftest_target2;
target_ip = get_ftrace_location(target);
diff --git a/lib/test_kprobes.c b/lib/test_kprobes.c
index eeb1d728d974..1c95e5719802 100644
--- a/lib/test_kprobes.c
+++ b/lib/test_kprobes.c
@@ -339,10 +339,7 @@ static int kprobes_test_init(struct kunit *test)
stacktrace_target = kprobe_stacktrace_target;
internal_target = kprobe_stacktrace_internal_target;
stacktrace_driver = kprobe_stacktrace_driver;
-
- do {
- rand1 = get_random_u32();
- } while (rand1 <= div_factor);
+ rand1 = get_random_u32_above(div_factor);
return 0;
}

diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
index 2685c3f15e9d..b5205311f372 100644
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -15,13 +15,7 @@ static u32 __ipv6_select_ident(struct net *net,
const struct in6_addr *dst,
const struct in6_addr *src)
{
- u32 id;
-
- do {
- id = get_random_u32();
- } while (!id);
-
- return id;
+ return get_random_u32_above(0);
}

/* This function exists only for tap drivers that must support broken
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index ff38c5a4d174..d593d5b6d4b1 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -626,8 +626,7 @@ static int __vsock_bind_connectible(struct vsock_sock *vsk,
struct sockaddr_vm new_addr;

if (!port)
- port = LAST_RESERVED_PORT + 1 +
- get_random_u32_below(U32_MAX - LAST_RESERVED_PORT);
+ port = get_random_u32_above(LAST_RESERVED_PORT);

vsock_addr_init(&new_addr, addr->svm_cid, addr->svm_port);

--
2.38.1