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From: Eliav Farber <farbere@amazon.com>
To: <gregkh@linuxfoundation.org>, <sashal@kernel.org>,
	<mario.limonciello@amd.com>, <lijo.lazar@amd.com>,
	<David.Laight@ACULAB.COM>, <arnd@kernel.org>,
	<linux-kernel@vger.kernel.org>, <stable@vger.kernel.org>,
	<farbere@amazon.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	David Laight <David.Laight@aculab.com>,
	Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Subject: [PATCH v2 02/13 6.1.y] minmax: add a few more MIN_T/MAX_T users
Date: Mon, 29 Sep 2025 18:33:47 +0000	[thread overview]
Message-ID: <20250929183358.18982-3-farbere@amazon.com> (raw)
In-Reply-To: <20250929183358.18982-1-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                         | 2 +-
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 +-
 net/ipv4/proc.c                                   | 2 +-
 net/ipv6/proc.c                                   | 2 +-
 7 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 77ee0012f849..a84d3d82824a 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 8e39370fdb5c..f0de7b18a53f 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 efd0732a8c10..a201019babe4 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -2618,7 +2618,7 @@ 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 948e35c405a8..be84aed47160 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2827,7 +2827,7 @@ 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 1f52c5f2d347..234b2e56be4f 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 e20b3705c2d2..5e01863be039 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


  parent reply	other threads:[~2025-09-29 18:34 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-29 18:33 [PATCH v2 00/13 6.1.y] Backport minmax.h updates from v6.17-rc7 Eliav Farber
2025-09-29 18:33 ` [PATCH v2 01/13 6.1.y] minmax: make generic MIN() and MAX() macros available everywhere Eliav Farber
2025-09-29 18:33 ` Eliav Farber [this message]
2025-09-29 18:33 ` [PATCH v2 03/13 6.1.y] minmax: simplify min()/max()/clamp() implementation Eliav Farber
2025-09-30 14:25   ` Greg KH
2025-09-30 14:49     ` Farber, Eliav
2025-09-29 18:33 ` [PATCH v2 04/13 6.1.y] minmax: don't use max() in situations that want a C constant expression Eliav Farber
2025-09-29 18:33 ` [PATCH v2 05/13 6.1.y] minmax: improve macro expansion and type checking Eliav Farber
2025-09-29 18:33 ` [PATCH v2 06/13 6.1.y] minmax: fix up min3() and max3() too Eliav Farber
2025-09-29 18:33 ` [PATCH v2 07/13 6.1.y] minmax.h: add whitespace around operators and after commas Eliav Farber
2025-09-29 18:33 ` [PATCH v2 08/13 6.1.y] minmax.h: update some comments Eliav Farber
2025-09-29 18:33 ` [PATCH v2 09/13 6.1.y] minmax.h: reduce the #define expansion of min(), max() and clamp() Eliav Farber
2025-09-29 18:33 ` [PATCH v2 10/13 6.1.y] minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp() Eliav Farber
2025-09-29 18:33 ` [PATCH v2 11/13 6.1.y] minmax.h: move all the clamp() definitions after the min/max() ones Eliav Farber
2025-09-29 18:33 ` [PATCH v2 12/13 6.1.y] minmax.h: simplify the variants of clamp() Eliav Farber
2025-09-29 18:33 ` [PATCH v2 13/13 6.1.y] minmax.h: remove some #defines that are only expanded once Eliav Farber

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