From: Eliav Farber <farbere@amazon.com>
To: <richard@nod.at>, <anton.ivanov@cambridgegreys.com>,
<johannes@sipsolutions.net>, <dave.hansen@linux.intel.com>,
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Cc: Linus Torvalds <torvalds@linux-foundation.org>,
David Laight <David.Laight@aculab.com>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Subject: [PATCH 03/15 6.6.y] minmax: add a few more MIN_T/MAX_T users
Date: Mon, 22 Sep 2025 10:32:29 +0000 [thread overview]
Message-ID: <20250922103241.16213-4-farbere@amazon.com> (raw)
In-Reply-To: <20250922103241.16213-1-farbere@amazon.com>
From: Linus Torvalds <torvalds@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/b47fad1d0cf8449886ad148f8c013dae@AcuMS.aculab.com/
Cc: David Laight <David.Laight@aculab.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Eliav Farber <farbere@amazon.com>
---
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(-)
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index b18f5a71e679..98aa303ad054 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -107,7 +107,7 @@ static inline void pgd_list_del(pgd_t *pgd)
#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)
diff --git a/drivers/edac/sb_edac.c b/drivers/edac/sb_edac.c
index 0c779a0326b6..6c3a40e6f4c6 100644
--- 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 {
diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c
index d021497841b8..3969dc548cff 100644
--- 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(struct drm_plane *plane,
{
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;
diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 1e27a5bce2d9..0bd76f8d4dc6 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -1794,7 +1794,7 @@ static void integrity_metadata(struct work_struct *w)
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 @@ static bool __journal_read_write(struct dm_integrity_io *dio, struct bio *bio,
} 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_integrity_c *ic, unsigned int write_start
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);
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index ff5389a8efc3..f3155d69a013 100644
--- 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 stmmac_priv *priv)
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)))
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index a85b0aba3646..b444767b15a5 100644
--- 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 [mea@utu.fi]
diff --git a/net/ipv6/proc.c b/net/ipv6/proc.c
index 6d1d9221649d..752327b10dde 100644
--- 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)
--
2.47.3
next prev parent reply other threads:[~2025-09-22 10:34 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-22 10:32 [PATCH 00/15 v6.6.y] Backport minmax.h updates from v6.17-rc7 Eliav Farber
2025-09-22 10:32 ` [PATCH 01/15 6.6.y] minmax: avoid overly complicated constant expressions in VM code Eliav Farber
2025-09-22 10:32 ` [PATCH 02/15 6.6.y] minmax: simplify and clarify min_t()/max_t() implementation Eliav Farber
2025-09-22 10:32 ` Eliav Farber [this message]
2025-09-22 10:32 ` [PATCH 04/15 6.6.y] minmax: make generic MIN() and MAX() macros available everywhere Eliav Farber
2025-09-22 10:32 ` [PATCH 05/15 6.6.y] minmax: simplify min()/max()/clamp() implementation Eliav Farber
2025-09-22 10:32 ` [PATCH 06/15 6.6.y] minmax: don't use max() in situations that want a C constant expression Eliav Farber
2025-09-22 10:32 ` [PATCH 07/15 6.6.y] minmax: improve macro expansion and type checking Eliav Farber
2025-09-22 10:32 ` [PATCH 08/15 6.6.y] minmax: fix up min3() and max3() too Eliav Farber
2025-09-22 10:32 ` [PATCH 09/15 6.6.y] minmax.h: add whitespace around operators and after commas Eliav Farber
2025-09-22 10:32 ` [PATCH 10/15 6.6.y] minmax.h: update some comments Eliav Farber
2025-09-22 10:32 ` [PATCH 11/15 6.6.y] minmax.h: reduce the #define expansion of min(), max() and clamp() Eliav Farber
2025-09-22 10:32 ` [PATCH 12/15 6.6.y] minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp() Eliav Farber
2025-09-22 10:32 ` [PATCH 13/15 6.6.y] minmax.h: move all the clamp() definitions after the min/max() ones Eliav Farber
2025-09-22 10:32 ` [PATCH 14/15 6.6.y] minmax.h: simplify the variants of clamp() Eliav Farber
2025-09-22 10:32 ` [PATCH 15/15 6.6.y] minmax.h: remove some #defines that are only expanded once Eliav Farber
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