treewide: use prandom_u32_max() when possible, part 1

Rather than incurring a division or requesting too many random bytes for
the given range, use the prandom_u32_max() function, which only takes
the minimum required bytes from the RNG and avoids divisions. This was
done mechanically with this coccinelle script:

@basic@
expression E;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u64;
@@
(
- ((T)get_random_u32() % (E))
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ((E) - 1))
+ prandom_u32_max(E * XXX_MAKE_SURE_E_IS_POW2)
|
- ((u64)(E) * get_random_u32() >> 32)
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ~PAGE_MASK)
+ prandom_u32_max(PAGE_SIZE)
)

@multi_line@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
identifier RAND;
expression E;
@@

-       RAND = get_random_u32();
        ... when != RAND
-       RAND %= (E);
+       RAND = prandom_u32_max(E);

// Find a potential literal
@literal_mask@
expression LITERAL;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
position p;
@@

        ((T)get_random_u32()@p & (LITERAL))

// Add one to the literal.
@script:python add_one@
literal << literal_mask.LITERAL;
RESULT;
@@

value = None
if literal.startswith('0x'):
        value = int(literal, 16)
elif literal[0] in '123456789':
        value = int(literal, 10)
if value is None:
        print("I don't know how to handle %s" % (literal))
        cocci.include_match(False)
elif value == 2**32 - 1 or value == 2**31 - 1 or value == 2**24 - 1 or value == 2**16 - 1 or value == 2**8 - 1:
        print("Skipping 0x%x for cleanup elsewhere" % (value))
        cocci.include_match(False)
elif value & (value + 1) != 0:
        print("Skipping 0x%x because it's not a power of two minus one" % (value))
        cocci.include_match(False)
elif literal.startswith('0x'):
        coccinelle.RESULT = cocci.make_expr("0x%x" % (value + 1))
else:
        coccinelle.RESULT = cocci.make_expr("%d" % (value + 1))

// Replace the literal mask with the calculated result.
@plus_one@
expression literal_mask.LITERAL;
position literal_mask.p;
expression add_one.RESULT;
identifier FUNC;
@@

-       (FUNC()@p & (LITERAL))
+       prandom_u32_max(RESULT)

@collapse_ret@
type T;
identifier VAR;
expression E;
@@

 {
-       T VAR;
-       VAR = (E);
-       return VAR;
+       return E;
 }

@drop_var@
type T;
identifier VAR;
@@

 {
-       T VAR;
        ... when != VAR
 }

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: KP Singh <kpsingh@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz> # for ext4 and sbitmap
Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> # for drbd
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

25 files changed, 41 insertions, 53 deletions

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index c897c4572036..ee69d50ba4fd 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -781,7 +781,7 @@ static struct socket *drbd_wait_for_connect(struct drbd_connection *connection,
 
 	timeo = connect_int * HZ;
 	/* 28.5% random jitter */
-	timeo += (prandom_u32() & 1) ? timeo / 7 : -timeo / 7;
+	timeo += prandom_u32_max(2) ? timeo / 7 : -timeo / 7;
 
 	err = wait_for_completion_interruptible_timeout(&ad->door_bell, timeo);
 	if (err <= 0)
@@ -1004,7 +1004,7 @@ retry:
 				drbd_warn(connection, "Error receiving initial packet\n");
 				sock_release(s);
 randomize:
-				if (prandom_u32() & 1)
+				if (prandom_u32_max(2))
 					goto retry;
 			}
 		}
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index cd75b0ca2555..845023c14eb3 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -2424,7 +2424,7 @@ gen8_dispatch_bsd_engine(struct drm_i915_private *dev_priv,
 	/* Check whether the file_priv has already selected one ring. */
 	if ((int)file_priv->bsd_engine < 0)
 		file_priv->bsd_engine =
-			get_random_int() % num_vcs_engines(dev_priv);
+			prandom_u32_max(num_vcs_engines(dev_priv));
 
 	return file_priv->bsd_engine;
 }
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 70da57ef2eeb..cc2222b85c88 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -3807,7 +3807,7 @@ static int cma_alloc_any_port(enum rdma_ucm_port_space ps,
 
 	inet_get_local_port_range(net, &low, &high);
 	remaining = (high - low) + 1;
-	rover = prandom_u32() % remaining + low;
+	rover = prandom_u32_max(remaining) + low;
 retry:
 	if (last_used_port != rover) {
 		struct rdma_bind_list *bind_list;
diff --git a/drivers/infiniband/hw/cxgb4/id_table.c b/drivers/infiniband/hw/cxgb4/id_table.c
index f64e7e02b129..280d61466855 100644
--- a/drivers/infiniband/hw/cxgb4/id_table.c
+++ b/drivers/infiniband/hw/cxgb4/id_table.c
@@ -54,7 +54,7 @@ u32 c4iw_id_alloc(struct c4iw_id_table *alloc)
 
 	if (obj < alloc->max) {
 		if (alloc->flags & C4IW_ID_TABLE_F_RANDOM)
-			alloc->last += prandom_u32() % RANDOM_SKIP;
+			alloc->last += prandom_u32_max(RANDOM_SKIP);
 		else
 			alloc->last = obj + 1;
 		if (alloc->last >= alloc->max)
@@ -85,7 +85,7 @@ int c4iw_id_table_alloc(struct c4iw_id_table *alloc, u32 start, u32 num,
 	alloc->start = start;
 	alloc->flags = flags;
 	if (flags & C4IW_ID_TABLE_F_RANDOM)
-		alloc->last = prandom_u32() % RANDOM_SKIP;
+		alloc->last = prandom_u32_max(RANDOM_SKIP);
 	else
 		alloc->last = 0;
 	alloc->max = num;
diff --git a/drivers/infiniband/hw/hns/hns_roce_ah.c b/drivers/infiniband/hw/hns/hns_roce_ah.c
index 492b122d0521..480c062dd04f 100644
--- a/drivers/infiniband/hw/hns/hns_roce_ah.c
+++ b/drivers/infiniband/hw/hns/hns_roce_ah.c
@@ -41,9 +41,8 @@ static inline u16 get_ah_udp_sport(const struct rdma_ah_attr *ah_attr)
 	u16 sport;
 
 	if (!fl)
-		sport = get_random_u32() %
-			(IB_ROCE_UDP_ENCAP_VALID_PORT_MAX + 1 -
-			 IB_ROCE_UDP_ENCAP_VALID_PORT_MIN) +
+		sport = prandom_u32_max(IB_ROCE_UDP_ENCAP_VALID_PORT_MAX + 1 -
+					IB_ROCE_UDP_ENCAP_VALID_PORT_MIN) +
 			IB_ROCE_UDP_ENCAP_VALID_PORT_MIN;
 	else
 		sport = rdma_flow_label_to_udp_sport(fl);
diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.c b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
index 758e1d7ebc36..8546b8816524 100644
--- a/drivers/infiniband/ulp/rtrs/rtrs-clt.c
+++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
@@ -1517,8 +1517,7 @@ static void rtrs_clt_err_recovery_work(struct work_struct *work)
 	rtrs_clt_stop_and_destroy_conns(clt_path);
 	queue_delayed_work(rtrs_wq, &clt_path->reconnect_dwork,
 			   msecs_to_jiffies(delay_ms +
-					    prandom_u32() %
-					    RTRS_RECONNECT_SEED));
+					    prandom_u32_max(RTRS_RECONNECT_SEED)));
 }
 
 static struct rtrs_clt_path *alloc_path(struct rtrs_clt_sess *clt,
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index f2c5a7e06fa9..3427555b0cca 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -401,7 +401,7 @@ static bool check_should_bypass(struct cached_dev *dc, struct bio *bio)
 	}
 
 	if (bypass_torture_test(dc)) {
-		if ((get_random_int() & 3) == 3)
+		if (prandom_u32_max(4) == 3)
 			goto skip;
 		else
 			goto rescale;
diff --git a/drivers/media/test-drivers/vivid/vivid-touch-cap.c b/drivers/media/test-drivers/vivid/vivid-touch-cap.c
index 64e3e4cb30c2..792660a85bc1 100644
--- a/drivers/media/test-drivers/vivid/vivid-touch-cap.c
+++ b/drivers/media/test-drivers/vivid/vivid-touch-cap.c
@@ -221,7 +221,7 @@ static void vivid_fill_buff_noise(__s16 *tch_buf, int size)
 
 static inline int get_random_pressure(void)
 {
-	return get_random_int() % VIVID_PRESSURE_LIMIT;
+	return prandom_u32_max(VIVID_PRESSURE_LIMIT);
 }
 
 static void vivid_tch_buf_set(struct v4l2_pix_format *f,
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index ef53a2578824..95fa8fb1d45f 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -97,8 +97,8 @@ static void mmc_should_fail_request(struct mmc_host *host,
 	    !should_fail(&host->fail_mmc_request, data->blksz * data->blocks))
 		return;
 
-	data->error = data_errors[prandom_u32() % ARRAY_SIZE(data_errors)];
-	data->bytes_xfered = (prandom_u32() % (data->bytes_xfered >> 9)) << 9;
+	data->error = data_errors[prandom_u32_max(ARRAY_SIZE(data_errors))];
+	data->bytes_xfered = prandom_u32_max(data->bytes_xfered >> 9) << 9;
 }
 
 #else /* CONFIG_FAIL_MMC_REQUEST */
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 581614196a84..c78bbc22e0d1 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -1858,7 +1858,7 @@ static void dw_mci_start_fault_timer(struct dw_mci *host)
 	 * Try to inject the error at random points during the data transfer.
 	 */
 	hrtimer_start(&host->fault_timer,
-		      ms_to_ktime(prandom_u32() % 25),
+		      ms_to_ktime(prandom_u32_max(25)),
 		      HRTIMER_MODE_REL);
 }
 
diff --git a/drivers/mtd/nand/raw/nandsim.c b/drivers/mtd/nand/raw/nandsim.c
index 24beade95c7f..50bcf745e816 100644
--- a/drivers/mtd/nand/raw/nandsim.c
+++ b/drivers/mtd/nand/raw/nandsim.c
@@ -1405,9 +1405,9 @@ static void ns_do_bit_flips(struct nandsim *ns, int num)
 	if (bitflips && prandom_u32() < (1 << 22)) {
 		int flips = 1;
 		if (bitflips > 1)
-			flips = (prandom_u32() % (int) bitflips) + 1;
+			flips = prandom_u32_max(bitflips) + 1;
 		while (flips--) {
-			int pos = prandom_u32() % (num * 8);
+			int pos = prandom_u32_max(num * 8);
 			ns->buf.byte[pos / 8] ^= (1 << (pos % 8));
 			NS_WARN("read_page: flipping bit %d in page %d "
 				"reading from %d ecc: corrected=%u failed=%u\n",
diff --git a/drivers/mtd/tests/mtd_nandecctest.c b/drivers/mtd/tests/mtd_nandecctest.c
index c4f271314f52..1c7201b0f372 100644
--- a/drivers/mtd/tests/mtd_nandecctest.c
+++ b/drivers/mtd/tests/mtd_nandecctest.c
@@ -47,7 +47,7 @@ struct nand_ecc_test {
 static void single_bit_error_data(void *error_data, void *correct_data,
 				size_t size)
 {
-	unsigned int offset = prandom_u32() % (size * BITS_PER_BYTE);
+	unsigned int offset = prandom_u32_max(size * BITS_PER_BYTE);
 
 	memcpy(error_data, correct_data, size);
 	__change_bit_le(offset, error_data);
@@ -58,9 +58,9 @@ static void double_bit_error_data(void *error_data, void *correct_data,
 {
 	unsigned int offset[2];
 
-	offset[0] = prandom_u32() % (size * BITS_PER_BYTE);
+	offset[0] = prandom_u32_max(size * BITS_PER_BYTE);
 	do {
-		offset[1] = prandom_u32() % (size * BITS_PER_BYTE);
+		offset[1] = prandom_u32_max(size * BITS_PER_BYTE);
 	} while (offset[0] == offset[1]);
 
 	memcpy(error_data, correct_data, size);
@@ -71,7 +71,7 @@ static void double_bit_error_data(void *error_data, void *correct_data,
 
 static unsigned int random_ecc_bit(size_t size)
 {
-	unsigned int offset = prandom_u32() % (3 * BITS_PER_BYTE);
+	unsigned int offset = prandom_u32_max(3 * BITS_PER_BYTE);
 
 	if (size == 256) {
 		/*
@@ -79,7 +79,7 @@ static unsigned int random_ecc_bit(size_t size)
 		 * and 17th bit) in ECC code for 256 byte data block
 		 */
 		while (offset == 16 || offset == 17)
-			offset = prandom_u32() % (3 * BITS_PER_BYTE);
+			offset = prandom_u32_max(3 * BITS_PER_BYTE);
 	}
 
 	return offset;
diff --git a/drivers/mtd/tests/stresstest.c b/drivers/mtd/tests/stresstest.c
index cb29c8c1b370..d2faaca7f19d 100644
--- a/drivers/mtd/tests/stresstest.c
+++ b/drivers/mtd/tests/stresstest.c
@@ -45,9 +45,8 @@ static int rand_eb(void)
 	unsigned int eb;
 
 again:
-	eb = prandom_u32();
 	/* Read or write up 2 eraseblocks at a time - hence 'ebcnt - 1' */
-	eb %= (ebcnt - 1);
+	eb = prandom_u32_max(ebcnt - 1);
 	if (bbt[eb])
 		goto again;
 	return eb;
@@ -55,20 +54,12 @@ again:
 
 static int rand_offs(void)
 {
-	unsigned int offs;
-
-	offs = prandom_u32();
-	offs %= bufsize;
-	return offs;
+	return prandom_u32_max(bufsize);
 }
 
 static int rand_len(int offs)
 {
-	unsigned int len;
-
-	len = prandom_u32();
-	len %= (bufsize - offs);
-	return len;
+	return prandom_u32_max(bufsize - offs);
 }
 
 static int do_read(void)
@@ -127,7 +118,7 @@ static int do_write(void)
 
 static int do_operation(void)
 {
-	if (prandom_u32() & 1)
+	if (prandom_u32_max(2))
 		return do_read();
 	else
 		return do_write();
diff --git a/drivers/mtd/ubi/debug.c b/drivers/mtd/ubi/debug.c
index 31d427ee191a..908d0e088557 100644
--- a/drivers/mtd/ubi/debug.c
+++ b/drivers/mtd/ubi/debug.c
@@ -590,7 +590,7 @@ int ubi_dbg_power_cut(struct ubi_device *ubi, int caller)
 
 		if (ubi->dbg.power_cut_max > ubi->dbg.power_cut_min) {
 			range = ubi->dbg.power_cut_max - ubi->dbg.power_cut_min;
-			ubi->dbg.power_cut_counter += prandom_u32() % range;
+			ubi->dbg.power_cut_counter += prandom_u32_max(range);
 		}
 		return 0;
 	}
diff --git a/drivers/mtd/ubi/debug.h b/drivers/mtd/ubi/debug.h
index 118248a5d7d4..dc8d8f83657a 100644
--- a/drivers/mtd/ubi/debug.h
+++ b/drivers/mtd/ubi/debug.h
@@ -73,7 +73,7 @@ static inline int ubi_dbg_is_bgt_disabled(const struct ubi_device *ubi)
 static inline int ubi_dbg_is_bitflip(const struct ubi_device *ubi)
 {
 	if (ubi->dbg.emulate_bitflips)
-		return !(prandom_u32() % 200);
+		return !prandom_u32_max(200);
 	return 0;
 }
 
@@ -87,7 +87,7 @@ static inline int ubi_dbg_is_bitflip(const struct ubi_device *ubi)
 static inline int ubi_dbg_is_write_failure(const struct ubi_device *ubi)
 {
 	if (ubi->dbg.emulate_io_failures)
-		return !(prandom_u32() % 500);
+		return !prandom_u32_max(500);
 	return 0;
 }
 
@@ -101,7 +101,7 @@ static inline int ubi_dbg_is_write_failure(const struct ubi_device *ubi)
 static inline int ubi_dbg_is_erase_failure(const struct ubi_device *ubi)
 {
 	if (ubi->dbg.emulate_io_failures)
-		return !(prandom_u32() % 400);
+		return !prandom_u32_max(400);
 	return 0;
 }
 
diff --git a/drivers/net/ethernet/broadcom/cnic.c b/drivers/net/ethernet/broadcom/cnic.c
index e86503d97f32..f597b313acaa 100644
--- a/drivers/net/ethernet/broadcom/cnic.c
+++ b/drivers/net/ethernet/broadcom/cnic.c
@@ -4105,8 +4105,7 @@ static int cnic_cm_alloc_mem(struct cnic_dev *dev)
 	for (i = 0; i < MAX_CM_SK_TBL_SZ; i++)
 		atomic_set(&cp->csk_tbl[i].ref_count, 0);
 
-	port_id = prandom_u32();
-	port_id %= CNIC_LOCAL_PORT_RANGE;
+	port_id = prandom_u32_max(CNIC_LOCAL_PORT_RANGE);
 	if (cnic_init_id_tbl(&cp->csk_port_tbl, CNIC_LOCAL_PORT_RANGE,
 			     CNIC_LOCAL_PORT_MIN, port_id)) {
 		cnic_cm_free_mem(dev);
diff --git a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_io.c b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_io.c
index 539992dad8ba..a4256087ac82 100644
--- a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_io.c
+++ b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_io.c
@@ -919,8 +919,8 @@ static int csk_wait_memory(struct chtls_dev *cdev,
 	current_timeo = *timeo_p;
 	noblock = (*timeo_p ? false : true);
 	if (csk_mem_free(cdev, sk)) {
-		current_timeo = (prandom_u32() % (HZ / 5)) + 2;
-		vm_wait = (prandom_u32() % (HZ / 5)) + 2;
+		current_timeo = prandom_u32_max(HZ / 5) + 2;
+		vm_wait = prandom_u32_max(HZ / 5) + 2;
 	}
 
 	add_wait_queue(sk_sleep(sk), &wait);
diff --git a/drivers/net/hamradio/baycom_epp.c b/drivers/net/hamradio/baycom_epp.c
index 3e69079ed694..7df78a721b04 100644
--- a/drivers/net/hamradio/baycom_epp.c
+++ b/drivers/net/hamradio/baycom_epp.c
@@ -438,7 +438,7 @@ static int transmit(struct baycom_state *bc, int cnt, unsigned char stat)
 			if ((--bc->hdlctx.slotcnt) > 0)
 				return 0;
 			bc->hdlctx.slotcnt = bc->ch_params.slottime;
-			if ((prandom_u32() % 256) > bc->ch_params.ppersist)
+			if (prandom_u32_max(256) > bc->ch_params.ppersist)
 				return 0;
 		}
 	}
diff --git a/drivers/net/hamradio/hdlcdrv.c b/drivers/net/hamradio/hdlcdrv.c
index a6184d6c7b15..bef904325a0f 100644
--- a/drivers/net/hamradio/hdlcdrv.c
+++ b/drivers/net/hamradio/hdlcdrv.c
@@ -377,7 +377,7 @@ void hdlcdrv_arbitrate(struct net_device *dev, struct hdlcdrv_state *s)
 	if ((--s->hdlctx.slotcnt) > 0)
 		return;
 	s->hdlctx.slotcnt = s->ch_params.slottime;
-	if ((prandom_u32() % 256) > s->ch_params.ppersist)
+	if (prandom_u32_max(256) > s->ch_params.ppersist)
 		return;
 	start_tx(dev, s);
 }
diff --git a/drivers/net/hamradio/yam.c b/drivers/net/hamradio/yam.c
index 980f2be32f05..97a6cc5c7ae8 100644
--- a/drivers/net/hamradio/yam.c
+++ b/drivers/net/hamradio/yam.c
@@ -626,7 +626,7 @@ static void yam_arbitrate(struct net_device *dev)
 	yp->slotcnt = yp->slot / 10;
 
 	/* is random > persist ? */
-	if ((prandom_u32() % 256) > yp->pers)
+	if (prandom_u32_max(256) > yp->pers)
 		return;
 
 	yam_start_tx(dev, yp);
diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
index 9e9adde335c8..349b7b1dbbf2 100644
--- a/drivers/net/phy/at803x.c
+++ b/drivers/net/phy/at803x.c
@@ -1758,7 +1758,7 @@ static int qca808x_phy_fast_retrain_config(struct phy_device *phydev)
 
 static int qca808x_phy_ms_random_seed_set(struct phy_device *phydev)
 {
-	u16 seed_value = (prandom_u32() % QCA808X_MASTER_SLAVE_SEED_RANGE);
+	u16 seed_value = prandom_u32_max(QCA808X_MASTER_SLAVE_SEED_RANGE);
 
 	return at803x_debug_reg_mask(phydev, QCA808X_PHY_DEBUG_LOCAL_SEED,
 			QCA808X_MASTER_SLAVE_SEED_CFG,
diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
index 479041f070f9..10d9d9c63b28 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
@@ -1128,7 +1128,7 @@ static void brcmf_p2p_afx_handler(struct work_struct *work)
 	if (afx_hdl->is_listen && afx_hdl->my_listen_chan)
 		/* 100ms ~ 300ms */
 		err = brcmf_p2p_discover_listen(p2p, afx_hdl->my_listen_chan,
-						100 * (1 + prandom_u32() % 3));
+						100 * (1 + prandom_u32_max(3)));
 	else
 		err = brcmf_p2p_act_frm_search(p2p, afx_hdl->peer_listen_chan);
 
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c b/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c
index ed586e6d7d64..de0c545d50fd 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c
@@ -1099,7 +1099,7 @@ static void iwl_mvm_mac_ctxt_cmd_fill_ap(struct iwl_mvm *mvm,
 			iwl_mvm_mac_ap_iterator, &data);
 
 		if (data.beacon_device_ts) {
-			u32 rand = (prandom_u32() % (64 - 36)) + 36;
+			u32 rand = prandom_u32_max(64 - 36) + 36;
 			mvmvif->ap_beacon_time = data.beacon_device_ts +
 				ieee80211_tu_to_usec(data.beacon_int * rand /
 						     100);
diff --git a/drivers/scsi/fcoe/fcoe_ctlr.c b/drivers/scsi/fcoe/fcoe_ctlr.c
index 39e16eab47aa..ddc048069af2 100644
--- a/drivers/scsi/fcoe/fcoe_ctlr.c
+++ b/drivers/scsi/fcoe/fcoe_ctlr.c
@@ -2233,7 +2233,7 @@ static void fcoe_ctlr_vn_restart(struct fcoe_ctlr *fip)
 
 	if (fip->probe_tries < FIP_VN_RLIM_COUNT) {
 		fip->probe_tries++;
-		wait = prandom_u32() % FIP_VN_PROBE_WAIT;
+		wait = prandom_u32_max(FIP_VN_PROBE_WAIT);
 	} else
 		wait = FIP_VN_RLIM_INT;
 	mod_timer(&fip->timer, jiffies + msecs_to_jiffies(wait));
@@ -3125,7 +3125,7 @@ static void fcoe_ctlr_vn_timeout(struct fcoe_ctlr *fip)
 					  fcoe_all_vn2vn, 0);
 			fip->port_ka_time = jiffies +
 				 msecs_to_jiffies(FIP_VN_BEACON_INT +
-					(prandom_u32() % FIP_VN_BEACON_FUZZ));
+					prandom_u32_max(FIP_VN_BEACON_FUZZ));
 		}
 		if (time_before(fip->port_ka_time, next_time))
 			next_time = fip->port_ka_time;
diff --git a/drivers/scsi/qedi/qedi_main.c b/drivers/scsi/qedi/qedi_main.c
index cecfb2cb4c7b..df2fe7bd26d1 100644
--- a/drivers/scsi/qedi/qedi_main.c
+++ b/drivers/scsi/qedi/qedi_main.c
@@ -618,7 +618,7 @@ static int qedi_cm_alloc_mem(struct qedi_ctx *qedi)
 				sizeof(struct qedi_endpoint *)), GFP_KERNEL);
 	if (!qedi->ep_tbl)
 		return -ENOMEM;
-	port_id = prandom_u32() % QEDI_LOCAL_PORT_RANGE;
+	port_id = prandom_u32_max(QEDI_LOCAL_PORT_RANGE);
 	if (qedi_init_id_tbl(&qedi->lcl_port_tbl, QEDI_LOCAL_PORT_RANGE,
 			     QEDI_LOCAL_PORT_MIN, port_id)) {
 		qedi_cm_free_mem(qedi);