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Message-Id: <20221007180107.216067-3-Jason@zx2c4.com> Date: Fri, 7 Oct 2022 12:01:03 -0600 From: "Jason A. Donenfeld" <Jason@...c4.com> To: linux-kernel@...r.kernel.org, patches@...ts.linux.dev Cc: "Jason A. Donenfeld" <Jason@...c4.com>, Andreas Noever <andreas.noever@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Borislav Petkov <bp@...en8.de>, Catalin Marinas <catalin.marinas@....com>, Christoph Böhmwalder <christoph.boehmwalder@...bit.com>, Christoph Hellwig <hch@....de>, Christophe Leroy <christophe.leroy@...roup.eu>, Daniel Borkmann <daniel@...earbox.net>, Dave Airlie <airlied@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>, "David S . Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Florian Westphal <fw@...len.de>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "H . Peter Anvin" <hpa@...or.com>, Heiko Carstens <hca@...ux.ibm.com>, Helge Deller <deller@....de>, Herbert Xu <herbert@...dor.apana.org.au>, Huacai Chen <chenhuacai@...nel.org>, Hugh Dickins <hughd@...gle.com>, Jakub Kicinski <kuba@...nel.org>, "James E . J . Bottomley" <jejb@...ux.ibm.com>, Jan Kara <jack@...e.com>, Jason Gunthorpe <jgg@...pe.ca>, Jens Axboe <axboe@...nel.dk>, Johannes Berg <johannes@...solutions.net>, Jonathan Corbet <corbet@....net>, Jozsef Kadlecsik <kadlec@...filter.org>, KP Singh <kpsingh@...nel.org>, Kees Cook <keescook@...omium.org>, Marco Elver <elver@...gle.com>, Mauro Carvalho Chehab <mchehab@...nel.org>, Michael Ellerman <mpe@...erman.id.au>, Pablo Neira Ayuso <pablo@...filter.org>, Paolo Abeni <pabeni@...hat.com>, Peter Zijlstra <peterz@...radead.org>, Richard Weinberger <richard@....at>, Russell King <linux@...linux.org.uk>, Theodore Ts'o <tytso@....edu>, Thomas Bogendoerfer <tsbogend@...ha.franken.de>, Thomas Gleixner <tglx@...utronix.de>, Thomas Graf <tgraf@...g.ch>, Ulf Hansson <ulf.hansson@...aro.org>, Vignesh Raghavendra <vigneshr@...com>, WANG Xuerui <kernel@...0n.name>, Will Deacon <will@...nel.org>, Yury Norov <yury.norov@...il.com>, dri-devel@...ts.freedesktop.org, kasan-dev@...glegroups.com, kernel-janitors@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, linux-block@...r.kernel.org, linux-crypto@...r.kernel.org, linux-doc@...r.kernel.org, linux-fsdevel@...r.kernel.org, linux-media@...r.kernel.org, linux-mips@...r.kernel.org, linux-mm@...ck.org, linux-mmc@...r.kernel.org, linux-mtd@...ts.infradead.org, linux-nvme@...ts.infradead.org, linux-parisc@...r.kernel.org, linux-rdma@...r.kernel.org, linux-s390@...r.kernel.org, linux-um@...ts.infradead.org, linux-usb@...r.kernel.org, linux-wireless@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, loongarch@...ts.linux.dev, netdev@...r.kernel.org, sparclinux@...r.kernel.org, x86@...nel.org, Jan Kara <jack@...e.cz> Subject: [PATCH v4 2/6] treewide: use prandom_u32_max() when possible 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. Reviewed-by: Kees Cook <keescook@...omium.org> Reviewed-by: KP Singh <kpsingh@...nel.org> Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@...bit.com> # for drbd Reviewed-by: Jan Kara <jack@...e.cz> # for ext2, ext4, and sbitmap Signed-off-by: Jason A. Donenfeld <Jason@...c4.com> --- arch/arm64/kernel/process.c | 2 +- arch/loongarch/kernel/process.c | 2 +- arch/loongarch/kernel/vdso.c | 2 +- arch/mips/kernel/process.c | 2 +- arch/mips/kernel/vdso.c | 2 +- arch/parisc/kernel/vdso.c | 2 +- arch/powerpc/kernel/process.c | 2 +- arch/s390/kernel/process.c | 2 +- drivers/block/drbd/drbd_receiver.c | 4 ++-- drivers/md/bcache/request.c | 2 +- drivers/mtd/tests/stresstest.c | 17 ++++------------- drivers/mtd/ubi/debug.h | 6 +++--- drivers/net/ethernet/broadcom/cnic.c | 3 +-- fs/ext2/ialloc.c | 3 +-- fs/ext4/ialloc.c | 5 ++--- fs/ubifs/lpt_commit.c | 2 +- fs/ubifs/tnc_commit.c | 2 +- fs/xfs/libxfs/xfs_alloc.c | 2 +- fs/xfs/libxfs/xfs_ialloc.c | 2 +- include/linux/nodemask.h | 2 +- lib/cmdline_kunit.c | 4 ++-- lib/kobject.c | 2 +- lib/reed_solomon/test_rslib.c | 2 +- lib/sbitmap.c | 2 +- lib/test_hexdump.c | 2 +- lib/test_vmalloc.c | 17 ++++------------- net/core/pktgen.c | 4 ++-- net/ipv4/inet_hashtables.c | 2 +- net/sunrpc/cache.c | 2 +- net/sunrpc/xprtsock.c | 2 +- 30 files changed, 42 insertions(+), 63 deletions(-) diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 92bcc1768f0b..87203429f802 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -595,7 +595,7 @@ unsigned long __get_wchan(struct task_struct *p) unsigned long arch_align_stack(unsigned long sp) { if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) - sp -= get_random_int() & ~PAGE_MASK; + sp -= prandom_u32_max(PAGE_SIZE); return sp & ~0xf; } diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/process.c index 660492f064e7..1256e3582475 100644 --- a/arch/loongarch/kernel/process.c +++ b/arch/loongarch/kernel/process.c @@ -293,7 +293,7 @@ unsigned long stack_top(void) unsigned long arch_align_stack(unsigned long sp) { if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) - sp -= get_random_int() & ~PAGE_MASK; + sp -= prandom_u32_max(PAGE_SIZE); return sp & STACK_ALIGN; } diff --git a/arch/loongarch/kernel/vdso.c b/arch/loongarch/kernel/vdso.c index f32c38abd791..8c9826062652 100644 --- a/arch/loongarch/kernel/vdso.c +++ b/arch/loongarch/kernel/vdso.c @@ -78,7 +78,7 @@ static unsigned long vdso_base(void) unsigned long base = STACK_TOP; if (current->flags & PF_RANDOMIZE) { - base += get_random_int() & (VDSO_RANDOMIZE_SIZE - 1); + base += prandom_u32_max(VDSO_RANDOMIZE_SIZE); base = PAGE_ALIGN(base); } diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index 35b912bce429..bbe9ce471791 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -711,7 +711,7 @@ unsigned long mips_stack_top(void) unsigned long arch_align_stack(unsigned long sp) { if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) - sp -= get_random_int() & ~PAGE_MASK; + sp -= prandom_u32_max(PAGE_SIZE); return sp & ALMASK; } diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c index b2cc2c2dd4bf..5fd9bf1d596c 100644 --- a/arch/mips/kernel/vdso.c +++ b/arch/mips/kernel/vdso.c @@ -79,7 +79,7 @@ static unsigned long vdso_base(void) } if (current->flags & PF_RANDOMIZE) { - base += get_random_int() & (VDSO_RANDOMIZE_SIZE - 1); + base += prandom_u32_max(VDSO_RANDOMIZE_SIZE); base = PAGE_ALIGN(base); } diff --git a/arch/parisc/kernel/vdso.c b/arch/parisc/kernel/vdso.c index 63dc44c4c246..47e5960a2f96 100644 --- a/arch/parisc/kernel/vdso.c +++ b/arch/parisc/kernel/vdso.c @@ -75,7 +75,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, map_base = mm->mmap_base; if (current->flags & PF_RANDOMIZE) - map_base -= (get_random_int() & 0x1f) * PAGE_SIZE; + map_base -= prandom_u32_max(0x20) * PAGE_SIZE; vdso_text_start = get_unmapped_area(NULL, map_base, vdso_text_len, 0, 0); diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 0fbda89cd1bb..ff920f4d4317 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -2308,6 +2308,6 @@ void notrace __ppc64_runlatch_off(void) unsigned long arch_align_stack(unsigned long sp) { if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) - sp -= get_random_int() & ~PAGE_MASK; + sp -= prandom_u32_max(PAGE_SIZE); return sp & ~0xf; } diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c index d5119e039d85..5ec78555dd2e 100644 --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -224,7 +224,7 @@ unsigned long __get_wchan(struct task_struct *p) unsigned long arch_align_stack(unsigned long sp) { if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) - sp -= get_random_int() & ~PAGE_MASK; + sp -= prandom_u32_max(PAGE_SIZE); return sp & ~0xf; } diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c index af4c7d65490b..d8b1417dc503 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 @@ static int conn_connect(struct drbd_connection *connection) 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/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/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 @@ static int rand_eb(void) 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.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/fs/ext2/ialloc.c b/fs/ext2/ialloc.c index 998dd2ac8008..f4944c4dee60 100644 --- a/fs/ext2/ialloc.c +++ b/fs/ext2/ialloc.c @@ -277,8 +277,7 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent) int best_ndir = inodes_per_group; int best_group = -1; - group = prandom_u32(); - parent_group = (unsigned)group % ngroups; + parent_group = prandom_u32_max(ngroups); for (i = 0; i < ngroups; i++) { group = (parent_group + i) % ngroups; desc = ext2_get_group_desc (sb, group, NULL); diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c index f73e5eb43eae..36d5bc595cc2 100644 --- a/fs/ext4/ialloc.c +++ b/fs/ext4/ialloc.c @@ -463,10 +463,9 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent, hinfo.hash_version = DX_HASH_HALF_MD4; hinfo.seed = sbi->s_hash_seed; ext4fs_dirhash(parent, qstr->name, qstr->len, &hinfo); - grp = hinfo.hash; + parent_group = hinfo.hash % ngroups; } else - grp = prandom_u32(); - parent_group = (unsigned)grp % ngroups; + parent_group = prandom_u32_max(ngroups); for (i = 0; i < ngroups; i++) { g = (parent_group + i) % ngroups; get_orlov_stats(sb, g, flex_size, &stats); diff --git a/fs/ubifs/lpt_commit.c b/fs/ubifs/lpt_commit.c index cd4d5726a78d..cfbc31f709f4 100644 --- a/fs/ubifs/lpt_commit.c +++ b/fs/ubifs/lpt_commit.c @@ -1970,7 +1970,7 @@ static int dbg_populate_lsave(struct ubifs_info *c) if (!dbg_is_chk_gen(c)) return 0; - if (prandom_u32() & 3) + if (prandom_u32_max(4)) return 0; for (i = 0; i < c->lsave_cnt; i++) diff --git a/fs/ubifs/tnc_commit.c b/fs/ubifs/tnc_commit.c index 58c92c96ecef..01362ad5f804 100644 --- a/fs/ubifs/tnc_commit.c +++ b/fs/ubifs/tnc_commit.c @@ -700,7 +700,7 @@ static int alloc_idx_lebs(struct ubifs_info *c, int cnt) c->ilebs[c->ileb_cnt++] = lnum; dbg_cmt("LEB %d", lnum); } - if (dbg_is_chk_index(c) && !(prandom_u32() & 7)) + if (dbg_is_chk_index(c) && !prandom_u32_max(8)) return -ENOSPC; return 0; } diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c index e2bdf089c0a3..6261599bb389 100644 --- a/fs/xfs/libxfs/xfs_alloc.c +++ b/fs/xfs/libxfs/xfs_alloc.c @@ -1520,7 +1520,7 @@ xfs_alloc_ag_vextent_lastblock( #ifdef DEBUG /* Randomly don't execute the first algorithm. */ - if (prandom_u32() & 1) + if (prandom_u32_max(2)) return 0; #endif diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c index 6cdfd64bc56b..7838b31126e2 100644 --- a/fs/xfs/libxfs/xfs_ialloc.c +++ b/fs/xfs/libxfs/xfs_ialloc.c @@ -636,7 +636,7 @@ xfs_ialloc_ag_alloc( /* randomly do sparse inode allocations */ if (xfs_has_sparseinodes(tp->t_mountp) && igeo->ialloc_min_blks < igeo->ialloc_blks) - do_sparse = prandom_u32() & 1; + do_sparse = prandom_u32_max(2); #endif /* diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h index 4b71a96190a8..66ee9b4b7925 100644 --- a/include/linux/nodemask.h +++ b/include/linux/nodemask.h @@ -509,7 +509,7 @@ static inline int node_random(const nodemask_t *maskp) w = nodes_weight(*maskp); if (w) bit = bitmap_ord_to_pos(maskp->bits, - get_random_int() % w, MAX_NUMNODES); + prandom_u32_max(w), MAX_NUMNODES); return bit; #else return 0; diff --git a/lib/cmdline_kunit.c b/lib/cmdline_kunit.c index e6a31c927b06..a72a2c16066e 100644 --- a/lib/cmdline_kunit.c +++ b/lib/cmdline_kunit.c @@ -76,7 +76,7 @@ static void cmdline_test_lead_int(struct kunit *test) int rc = cmdline_test_values[i]; int offset; - sprintf(in, "%u%s", prandom_u32_max(256), str); + sprintf(in, "%u%s", get_random_int() % 256, str); /* Only first '-' after the number will advance the pointer */ offset = strlen(in) - strlen(str) + !!(rc == 2); cmdline_do_one_test(test, in, rc, offset); @@ -94,7 +94,7 @@ static void cmdline_test_tail_int(struct kunit *test) int rc = strcmp(str, "") ? (strcmp(str, "-") ? 0 : 1) : 1; int offset; - sprintf(in, "%s%u", str, prandom_u32_max(256)); + sprintf(in, "%s%u", str, get_random_int() % 256); /* * Only first and leading '-' not followed by integer * will advance the pointer. diff --git a/lib/kobject.c b/lib/kobject.c index 5f0e71ab292c..a0b2dbfcfa23 100644 --- a/lib/kobject.c +++ b/lib/kobject.c @@ -694,7 +694,7 @@ static void kobject_release(struct kref *kref) { struct kobject *kobj = container_of(kref, struct kobject, kref); #ifdef CONFIG_DEBUG_KOBJECT_RELEASE - unsigned long delay = HZ + HZ * (get_random_int() & 0x3); + unsigned long delay = HZ + HZ * prandom_u32_max(4); pr_info("kobject: '%s' (%p): %s, parent %p (delayed %ld)\n", kobject_name(kobj), kobj, __func__, kobj->parent, delay); INIT_DELAYED_WORK(&kobj->release, kobject_delayed_cleanup); diff --git a/lib/reed_solomon/test_rslib.c b/lib/reed_solomon/test_rslib.c index 6faf9c9a6215..4d241bdc88aa 100644 --- a/lib/reed_solomon/test_rslib.c +++ b/lib/reed_solomon/test_rslib.c @@ -199,7 +199,7 @@ static int get_rcw_we(struct rs_control *rs, struct wspace *ws, derrlocs[i] = errloc; - if (ewsc && (prandom_u32() & 1)) { + if (ewsc && prandom_u32_max(2)) { /* Erasure with the symbol intact */ errlocs[errloc] = 2; } else { diff --git a/lib/sbitmap.c b/lib/sbitmap.c index c4f04edf3ee9..ef0661504561 100644 --- a/lib/sbitmap.c +++ b/lib/sbitmap.c @@ -21,7 +21,7 @@ static int init_alloc_hint(struct sbitmap *sb, gfp_t flags) int i; for_each_possible_cpu(i) - *per_cpu_ptr(sb->alloc_hint, i) = prandom_u32() % depth; + *per_cpu_ptr(sb->alloc_hint, i) = prandom_u32_max(depth); } return 0; } diff --git a/lib/test_hexdump.c b/lib/test_hexdump.c index 0927f44cd478..41a0321f641a 100644 --- a/lib/test_hexdump.c +++ b/lib/test_hexdump.c @@ -208,7 +208,7 @@ static void __init test_hexdump_overflow(size_t buflen, size_t len, static void __init test_hexdump_overflow_set(size_t buflen, bool ascii) { unsigned int i = 0; - int rs = (prandom_u32_max(2) + 1) * 16; + int rs = prandom_u32_max(2) + 1 * 16; do { int gs = 1 << i; diff --git a/lib/test_vmalloc.c b/lib/test_vmalloc.c index 4f2f2d1bac56..56ffaa8dd3f6 100644 --- a/lib/test_vmalloc.c +++ b/lib/test_vmalloc.c @@ -151,9 +151,7 @@ static int random_size_alloc_test(void) int i; for (i = 0; i < test_loop_count; i++) { - n = prandom_u32(); - n = (n % 100) + 1; - + n = prandom_u32_max(n % 100) + 1; p = vmalloc(n * PAGE_SIZE); if (!p) @@ -293,16 +291,12 @@ pcpu_alloc_test(void) return -1; for (i = 0; i < 35000; i++) { - unsigned int r; - - r = prandom_u32(); - size = (r % (PAGE_SIZE / 4)) + 1; + size = prandom_u32_max(PAGE_SIZE / 4) + 1; /* * Maximum PAGE_SIZE */ - r = prandom_u32(); - align = 1 << ((r % 11) + 1); + align = 1 << (prandom_u32_max(11) + 1); pcpu[i] = __alloc_percpu(size, align); if (!pcpu[i]) @@ -393,14 +387,11 @@ static struct test_driver { static void shuffle_array(int *arr, int n) { - unsigned int rnd; int i, j; for (i = n - 1; i > 0; i--) { - rnd = prandom_u32(); - /* Cut the range. */ - j = rnd % i; + j = prandom_u32_max(i); /* Swap indexes. */ swap(arr[i], arr[j]); diff --git a/net/core/pktgen.c b/net/core/pktgen.c index a13ee452429e..5ca4f953034c 100644 --- a/net/core/pktgen.c +++ b/net/core/pktgen.c @@ -2469,11 +2469,11 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev) } if ((pkt_dev->flags & F_VID_RND) && (pkt_dev->vlan_id != 0xffff)) { - pkt_dev->vlan_id = prandom_u32() & (4096 - 1); + pkt_dev->vlan_id = prandom_u32_max(4096); } if ((pkt_dev->flags & F_SVID_RND) && (pkt_dev->svlan_id != 0xffff)) { - pkt_dev->svlan_id = prandom_u32() & (4096 - 1); + pkt_dev->svlan_id = prandom_u32_max(4096); } if (pkt_dev->udp_src_min < pkt_dev->udp_src_max) { diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index b9d995b5ce24..9dc070f2018e 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -794,7 +794,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, * on low contention the randomness is maximal and on high contention * it may be inexistent. */ - i = max_t(int, i, (prandom_u32() & 7) * 2); + i = max_t(int, i, prandom_u32_max(8) * 2); WRITE_ONCE(table_perturb[index], READ_ONCE(table_perturb[index]) + i + 2); /* Head lock still held and bh's disabled */ diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index c3c693b51c94..f075a9fb5ccc 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -677,7 +677,7 @@ static void cache_limit_defers(void) /* Consider removing either the first or the last */ if (cache_defer_cnt > DFR_MAX) { - if (prandom_u32() & 1) + if (prandom_u32_max(2)) discard = list_entry(cache_defer_list.next, struct cache_deferred_req, recent); else diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index e976007f4fd0..c2caee703d2c 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -1619,7 +1619,7 @@ static int xs_get_random_port(void) if (max < min) return -EADDRINUSE; range = max - min + 1; - rand = (unsigned short) prandom_u32() % range; + rand = (unsigned short) prandom_u32_max(range); return rand + min; } -- 2.37.3
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