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From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
To:     linux-kernel@vger.kernel.org, patches@lists.linux.dev
Cc:     "Jason A. Donenfeld" <Jason@zx2c4.com>,
        Kees Cook <keescook@chromium.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jakub Kicinski <kuba@kernel.org>,
        Russell King <linux@armlinux.org.uk>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Heiko Carstens <hca@linux.ibm.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        =?UTF-8?q?Christoph=20B=C3=B6hmwalder?= 
        <christoph.boehmwalder@linbit.com>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        "Martin K . Petersen" <martin.petersen@oracle.com>,
        Theodore Ts'o <tytso@mit.edu>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Jaegeuk Kim <jaegeuk@kernel.org>,
        Richard Weinberger <richard@nod.at>,
        "Darrick J . Wong" <djwong@kernel.org>,
        SeongJae Park <sj@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Helge Deller <deller@gmx.de>, netdev@vger.kernel.org,
        linux-crypto@vger.kernel.org, linux-block@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-media@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev,
        linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-mmc@vger.kernel.org, linux-parisc@vger.kernel.org
Subject: [PATCH v2 2/3] treewide: use get_random_u32_{above,below}() instead of manual loop
Date:   Mon, 14 Nov 2022 17:45:57 +0100
Message-Id: <20221114164558.1180362-3-Jason@zx2c4.com>
In-Reply-To: <20221114164558.1180362-1-Jason@zx2c4.com>
References: <20221114164558.1180362-1-Jason@zx2c4.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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