This is a note to let you know that I've just added the patch titled
minmax: add a few more MIN_T/MAX_T users
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
minmax-add-a-few-more-min_t-max_t-users.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <sta...@vger.kernel.org> know about it.
>From prvs=353d6d59a=farb...@amazon.com Mon Sep 22 12:34:49 2025
From: Eliav Farber <farb...@amazon.com>
Date: Mon, 22 Sep 2025 10:32:29 +0000
Subject: minmax: add a few more MIN_T/MAX_T users
To: <rich...@nod.at>, <anton.iva...@cambridgegreys.com>,
<johan...@sipsolutions.net>, <dave.han...@linux.intel.com>, <l...@kernel.org>,
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Cc: Linus Torvalds <torva...@linux-foundation.org>, David Laight
<david.lai...@aculab.com>, Lorenzo Stoakes <lorenzo.stoa...@oracle.com>
Message-ID: <20250922103241.16213-4-farb...@amazon.com>
From: Linus Torvalds <torva...@linux-foundation.org>
[ Upstream commit 4477b39c32fdc03363affef4b11d48391e6dc9ff ]
Commit 3a7e02c040b1 ("minmax: avoid overly complicated constant
expressions in VM code") added the simpler MIN_T/MAX_T macros in order
to avoid some excessive expansion from the rather complicated regular
min/max macros.
The complexity of those macros stems from two issues:
(a) trying to use them in situations that require a C constant
expression (in static initializers and for array sizes)
(b) the type sanity checking
and MIN_T/MAX_T avoids both of these issues.
Now, in the whole (long) discussion about all this, it was pointed out
that the whole type sanity checking is entirely unnecessary for
min_t/max_t which get a fixed type that the comparison is done in.
But that still leaves min_t/max_t unnecessarily complicated due to
worries about the C constant expression case.
However, it turns out that there really aren't very many cases that use
min_t/max_t for this, and we can just force-convert those.
This does exactly that.
Which in turn will then allow for much simpler implementations of
min_t()/max_t(). All the usual "macros in all upper case will evaluate
the arguments multiple times" rules apply.
We should do all the same things for the regular min/max() vs MIN/MAX()
cases, but that has the added complexity of various drivers defining
their own local versions of MIN/MAX, so that needs another level of
fixes first.
Link:
https://lore.kernel.org/all/b47fad1d0cf8449886ad148f8c013...@acums.aculab.com/
Cc: David Laight <david.lai...@aculab.com>
Cc: Lorenzo Stoakes <lorenzo.stoa...@oracle.com>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Eliav Farber <farb...@amazon.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/x86/mm/pgtable.c | 2 +-
drivers/edac/sb_edac.c | 4 ++--
drivers/gpu/drm/drm_color_mgmt.c | 2 +-
drivers/md/dm-integrity.c | 6 +++---
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 +-
net/ipv4/proc.c | 2 +-
net/ipv6/proc.c | 2 +-
7 files changed, 10 insertions(+), 10 deletions(-)
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -107,7 +107,7 @@ static inline void pgd_list_del(pgd_t *p
#define UNSHARED_PTRS_PER_PGD \
(SHARED_KERNEL_PMD ? KERNEL_PGD_BOUNDARY : PTRS_PER_PGD)
#define MAX_UNSHARED_PTRS_PER_PGD \
- max_t(size_t, KERNEL_PGD_BOUNDARY, PTRS_PER_PGD)
+ MAX_T(size_t, KERNEL_PGD_BOUNDARY, PTRS_PER_PGD)
static void pgd_set_mm(pgd_t *pgd, struct mm_struct *mm)
--- a/drivers/edac/sb_edac.c
+++ b/drivers/edac/sb_edac.c
@@ -109,8 +109,8 @@ static const u32 knl_interleave_list[] =
0x104, 0x10c, 0x114, 0x11c, /* 20-23 */
};
#define MAX_INTERLEAVE \
- (max_t(unsigned int, ARRAY_SIZE(sbridge_interleave_list), \
- max_t(unsigned int, ARRAY_SIZE(ibridge_interleave_list), \
+ (MAX_T(unsigned int, ARRAY_SIZE(sbridge_interleave_list), \
+ MAX_T(unsigned int, ARRAY_SIZE(ibridge_interleave_list), \
ARRAY_SIZE(knl_interleave_list))))
struct interleave_pkg {
--- a/drivers/gpu/drm/drm_color_mgmt.c
+++ b/drivers/gpu/drm/drm_color_mgmt.c
@@ -532,7 +532,7 @@ int drm_plane_create_color_properties(st
{
struct drm_device *dev = plane->dev;
struct drm_property *prop;
- struct drm_prop_enum_list enum_list[max_t(int, DRM_COLOR_ENCODING_MAX,
+ struct drm_prop_enum_list enum_list[MAX_T(int, DRM_COLOR_ENCODING_MAX,
DRM_COLOR_RANGE_MAX)];
int i, len;
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -1794,7 +1794,7 @@ static void integrity_metadata(struct wo
struct bio *bio = dm_bio_from_per_bio_data(dio, sizeof(struct
dm_integrity_io));
char *checksums;
unsigned int extra_space = unlikely(digest_size > ic->tag_size)
? digest_size - ic->tag_size : 0;
- char checksums_onstack[max_t(size_t, HASH_MAX_DIGESTSIZE,
MAX_TAG_SIZE)];
+ char checksums_onstack[MAX_T(size_t, HASH_MAX_DIGESTSIZE,
MAX_TAG_SIZE)];
sector_t sector;
unsigned int sectors_to_process;
@@ -2073,7 +2073,7 @@ retry_kmap:
} while (++s < ic->sectors_per_block);
#ifdef INTERNAL_VERIFY
if (ic->internal_hash) {
- char checksums_onstack[max_t(size_t,
HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];
+ char checksums_onstack[MAX_T(size_t,
HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];
integrity_sector_checksum(ic,
logical_sector, mem + bv.bv_offset, checksums_onstack);
if (unlikely(memcmp(checksums_onstack,
journal_entry_tag(ic, je), ic->tag_size))) {
@@ -2638,7 +2638,7 @@ static void do_journal_write(struct dm_i
unlikely(from_replay) &&
#endif
ic->internal_hash) {
- char test_tag[max_t(size_t,
HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];
+ char test_tag[MAX_T(size_t,
HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];
integrity_sector_checksum(ic, sec + ((l
- j) << ic->sb->log2_sectors_per_block),
(char
*)access_journal_data(ic, i, l), test_tag);
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2841,7 +2841,7 @@ static void stmmac_dma_interrupt(struct
u32 channels_to_check = tx_channel_count > rx_channel_count ?
tx_channel_count : rx_channel_count;
u32 chan;
- int status[max_t(u32, MTL_MAX_TX_QUEUES, MTL_MAX_RX_QUEUES)];
+ int status[MAX_T(u32, MTL_MAX_TX_QUEUES, MTL_MAX_RX_QUEUES)];
/* Make sure we never check beyond our status buffer. */
if (WARN_ON_ONCE(channels_to_check > ARRAY_SIZE(status)))
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -43,7 +43,7 @@
#include <net/sock.h>
#include <net/raw.h>
-#define TCPUDP_MIB_MAX max_t(u32, UDP_MIB_MAX, TCP_MIB_MAX)
+#define TCPUDP_MIB_MAX MAX_T(u32, UDP_MIB_MAX, TCP_MIB_MAX)
/*
* Report socket allocation statistics [m...@utu.fi]
--- a/net/ipv6/proc.c
+++ b/net/ipv6/proc.c
@@ -27,7 +27,7 @@
#include <net/ipv6.h>
#define MAX4(a, b, c, d) \
- max_t(u32, max_t(u32, a, b), max_t(u32, c, d))
+ MAX_T(u32, MAX_T(u32, a, b), MAX_T(u32, c, d))
#define SNMP_MIB_MAX MAX4(UDP_MIB_MAX, TCP_MIB_MAX, \
IPSTATS_MIB_MAX, ICMP_MIB_MAX)
Patches currently in stable-queue which might be from farb...@amazon.com are
queue-6.6/minmax-don-t-use-max-in-situations-that-want-a-c-constant-expression.patch
queue-6.6/minmax-make-generic-min-and-max-macros-available-everywhere.patch
queue-6.6/minmax-fix-up-min3-and-max3-too.patch
queue-6.6/minmax-add-a-few-more-min_t-max_t-users.patch
queue-6.6/minmax-improve-macro-expansion-and-type-checking.patch
queue-6.6/minmax-avoid-overly-complicated-constant-expressions-in-vm-code.patch
queue-6.6/minmax-simplify-min-max-clamp-implementation.patch
queue-6.6/minmax-simplify-and-clarify-min_t-max_t-implementation.patch
