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From: david.laight.linux@gmail.com
To: linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
	netdev@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Jakub Sitnicki <jakub@cloudflare.com>,
	John Fastabend <john.fastabend@gmail.com>,
	Paolo Abeni <pabeni@redhat.com>,
	David Laight <david.laight.linux@gmail.com>
Subject: [PATCH 41/44] net/core: Change loop conditions so min() can be used
Date: Wed, 19 Nov 2025 22:41:37 +0000	[thread overview]
Message-ID: <20251119224140.8616-42-david.laight.linux@gmail.com> (raw)
In-Reply-To: <20251119224140.8616-1-david.laight.linux@gmail.com>

From: David Laight <david.laight.linux@gmail.com>

Loops like:
	int copied = ...;
	...
	while (copied) {
		use = min_t(type, copied, PAGE_SIZE - offset);
		...
		copied -= 0;
	}
can be converted to a plain min() if the comparison is changed to:
	while (copied > 0) {
This removes any chance of high bits being discded by min_t().
(In the case above PAGE_SIZE is 64bits so the 'int' cast is safe,
but there are plenty of cases where the check shows up bugs.)

Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
 net/core/datagram.c | 6 +++---
 net/core/skmsg.c    | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/core/datagram.c b/net/core/datagram.c
index c285c6465923..555f38b89729 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -664,8 +664,8 @@ int zerocopy_fill_skb_from_iter(struct sk_buff *skb,
 		head = compound_head(pages[n]);
 		order = compound_order(head);
 
-		for (refs = 0; copied != 0; start = 0) {
-			int size = min_t(int, copied, PAGE_SIZE - start);
+		for (refs = 0; copied > 0; start = 0) {
+			int size = min(copied, PAGE_SIZE - start);
 
 			if (pages[n] - head > (1UL << order) - 1) {
 				head = compound_head(pages[n]);
@@ -783,7 +783,7 @@ EXPORT_SYMBOL(__zerocopy_sg_from_iter);
  */
 int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from)
 {
-	int copy = min_t(int, skb_headlen(skb), iov_iter_count(from));
+	int copy = min(skb_headlen(skb), iov_iter_count(from));
 
 	/* copy up to skb headlen */
 	if (skb_copy_datagram_from_iter(skb, 0, from, copy))
diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index 2ac7731e1e0a..b58e319f4e2e 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -335,8 +335,8 @@ int sk_msg_zerocopy_from_iter(struct sock *sk, struct iov_iter *from,
 		bytes -= copied;
 		msg->sg.size += copied;
 
-		while (copied) {
-			use = min_t(int, copied, PAGE_SIZE - offset);
+		while (copied > 0) {
+			use = min(copied, PAGE_SIZE - offset);
 			sg_set_page(&msg->sg.data[msg->sg.end],
 				    pages[i], use, offset);
 			sg_unmark_end(&msg->sg.data[msg->sg.end]);
-- 
2.39.5


  parent reply	other threads:[~2025-11-19 22:42 UTC|newest]

Thread overview: 109+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-11-19 22:40 [PATCH 00/44] Change a lot of min_t() that might mask high bits david.laight.linux
2025-11-19 22:40 ` [PATCH 01/44] x86/asm/bitops: Change the return type of variable__ffs() to unsigned int david.laight.linux
2025-11-20 15:54   ` Yury Norov
2025-11-20 18:29     ` David Laight
2025-11-20 18:33       ` Yury Norov
2025-11-20 21:18         ` David Laight
2025-11-24 14:58           ` Yury Norov
2025-11-24 18:18             ` David Laight
2025-11-19 22:40 ` [PATCH 02/44] ext4: Fix saturation of 64bit inode times for old filesystems david.laight.linux
2025-11-19 22:40 ` [PATCH 03/44] perf: Fix branch stack callchain limit david.laight.linux
2025-11-26  5:25   ` Mi, Dapeng
2025-11-19 22:41 ` [PATCH 04/44] io_uring/net: Change some dubious min_t() david.laight.linux
2025-11-20 14:48   ` Jens Axboe
2025-11-20 15:48     ` David Laight
2025-11-20 15:53       ` Jens Axboe
2025-11-22 11:31         ` David Laight
2025-11-19 22:41 ` [PATCH 05/44] ipc/msg: Fix saturation of percpu counts in msgctl_info() david.laight.linux
2025-11-19 22:41 ` [PATCH 06/44] bpf: Verifier, remove some unusual uses of min_t() and max_t() david.laight.linux
2025-11-21 21:40   ` Alexei Starovoitov
2025-11-21 22:21     ` David Laight
2025-11-23 16:39       ` Alexei Starovoitov
2025-11-23 18:07         ` David Laight
2025-11-23 19:20           ` Alexei Starovoitov
2025-11-23 23:03             ` David Laight
2025-11-19 22:41 ` [PATCH 07/44] net/core/flow_dissector: Fix cap of __skb_flow_dissect() return value david.laight.linux
2025-11-19 22:41 ` [PATCH 08/44] net: ethtool: Use min3() instead of nested min_t(u16,...) david.laight.linux
2025-11-19 22:41 ` [PATCH 09/44] ipv6: __ip6_append_data() don't abuse max_t() casts david.laight.linux
2025-11-20  0:32   ` bot+bpf-ci
2025-11-20 11:16     ` David Laight
2025-11-20 13:50       ` Chris Mason
2025-11-19 22:41 ` [PATCH 10/44] x86/crypto: ctr_crypt() use min() instead of min_t() david.laight.linux
2025-11-19 22:41 ` [PATCH 11/44] arch/x96/kvm: " david.laight.linux
2025-11-19 22:41 ` [PATCH 12/44] block: " david.laight.linux
2025-11-20 14:44   ` Jens Axboe
2025-11-19 22:41 ` [PATCH 13/44] drivers/acpi: " david.laight.linux
2025-11-24 19:48   ` Rafael J. Wysocki
2025-11-19 22:41 ` [PATCH 14/44] drivers/char/hw_random: use min3() instead of nested min_t() david.laight.linux
2025-11-19 22:41 ` [PATCH 15/44] drivers/char/tpm: use min() instead of min_t() david.laight.linux
2025-11-21 20:11   ` Jarkko Sakkinen
2025-11-19 22:41 ` [PATCH 16/44] drivers/crypto/ccp: " david.laight.linux
2025-11-19 22:41 ` [PATCH 17/44] drivers/cxl: " david.laight.linux
2025-11-19 23:50   ` Dave Jiang
2025-11-19 22:41 ` [PATCH 18/44] drivers/gpio: " david.laight.linux
2025-11-20  8:01   ` Andy Shevchenko
2025-11-20  9:37     ` David Laight
2025-11-25  9:55       ` Andy Shevchenko
2025-11-19 22:41 ` [PATCH 19/44] drivers/gpu/drm/amd: " david.laight.linux
2025-11-19 22:41 ` [PATCH 20/44] drivers/i2c/busses: " david.laight.linux
2026-01-20 13:19   ` Andi Shyti
2025-11-19 22:41 ` [PATCH 21/44] drivers/net/ethernet/realtek: " david.laight.linux
2025-11-19 22:41 ` [PATCH 22/44] drivers/nvme: " david.laight.linux
2025-11-19 22:41 ` [PATCH 23/44] arch/x86/mm: " david.laight.linux
2025-11-19 22:41 ` [PATCH 24/44] drivers/nvmem: " david.laight.linux
2025-11-19 22:41 ` [PATCH 25/44] drivers/pci: " david.laight.linux
2025-11-24 21:04   ` Bjorn Helgaas
2025-11-24 21:42     ` David Laight
2025-11-19 22:41 ` [PATCH 26/44] drivers/scsi: " david.laight.linux
2025-11-19 23:09   ` Bart Van Assche
2025-11-20 18:44     ` David Laight
2025-11-22 21:50     ` David Laight
2025-11-19 22:41 ` [PATCH 27/44] drivers/tty/vt: use umin() instead of min_t(u16, ...) for row/col limits david.laight.linux
2025-11-20  7:23   ` Jiri Slaby
2025-11-19 22:41 ` [PATCH 28/44] drivers/usb/storage: use min() instead of min_t() david.laight.linux
2025-11-20  2:59   ` Alan Stern
2025-11-20  9:18     ` David Laight
2025-11-20 14:39       ` [usb-storage] " Alan Stern
2025-11-19 22:41 ` [PATCH 29/44] drivers/xen: " david.laight.linux
2025-11-20  8:13   ` Jürgen Groß
2025-11-19 22:41 ` [PATCH 30/44] fs: use min() or umin() " david.laight.linux
2025-11-25  9:06   ` Christian Brauner
2026-01-12 21:51   ` Brian Masney
2026-01-13  9:42     ` David Laight
2026-01-13 16:56   ` Mark Brown
2026-01-13 18:33     ` David Laight
2026-01-13 19:10       ` Mark Brown
2026-01-13 19:24       ` David Laight
2025-11-19 22:41 ` [PATCH 31/44] block: bvec.h: use min() " david.laight.linux
2025-11-19 22:41 ` [PATCH 32/44] nodemask: " david.laight.linux
2025-11-20 15:19   ` Yury Norov
2025-11-19 22:41 ` [PATCH 33/44] ipc: " david.laight.linux
2025-11-19 22:41 ` [PATCH 34/44] bpf: " david.laight.linux
2025-11-19 22:41 ` [PATCH 35/44] " david.laight.linux
2025-11-19 22:41 ` [PATCH 36/44] lib/bucket_locks: " david.laight.linux
2025-11-19 22:41 ` [PATCH 37/44] lib/crypto/mpi: " david.laight.linux
2025-11-19 22:41 ` [PATCH 38/44] lib/dynamic_queue_limits: use max() instead of max_t() david.laight.linux
2025-11-19 22:41 ` [PATCH 39/44] mm: use min() instead of min_t() david.laight.linux
2025-11-20  9:20   ` David Hildenbrand (Red Hat)
2025-11-20  9:59     ` David Laight
2025-11-20 23:45       ` Eric Biggers
2025-11-21  8:27         ` David Hildenbrand (Red Hat)
2025-11-21  9:15         ` David Laight
2025-11-20 10:36   ` Lorenzo Stoakes
2025-11-20 12:09     ` Lorenzo Stoakes
2025-11-20 12:55     ` David Laight
2025-11-20 13:42       ` David Hildenbrand (Red Hat)
2025-11-20 15:44         ` David Laight
2025-11-21  8:24           ` David Hildenbrand (Red Hat)
2025-11-19 22:41 ` [PATCH 40/44] net: Don't pass bitfields to max_t() david.laight.linux
2025-11-19 22:41 ` david.laight.linux [this message]
2025-11-19 22:41 ` [PATCH 42/44] net: use min() instead of min_t() david.laight.linux
2025-11-19 22:41 ` [PATCH 43/44] net/netlink: Use umin() to avoid min_t(int, ...) discarding high bits david.laight.linux
2025-11-19 22:41 ` [PATCH 44/44] net/mptcp: Change some dubious min_t(int, ...) to min() david.laight.linux
2025-12-18 17:33   ` Matthieu Baerts
2025-12-18 20:15     ` David Laight
2025-12-19 10:48       ` Matthieu Baerts
2025-11-20  1:47 ` [PATCH 00/44] Change a lot of min_t() that might mask high bits Jakub Kicinski
2025-11-20  9:38 ` Lorenzo Stoakes
2025-11-20 14:52 ` (subset) " Jens Axboe
2025-11-24  9:49 ` Herbert Xu

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