[PATCH v2 00/12 6.6.y] Backport minmax.h updates from v6.17-rc7

[PATCH v2 00/12 6.6.y] Backport minmax.h updates from v6.17-rc7

[Eliav Farber]

This series backports 15 patches to update minmax.h in the 6.6.y branch,
aligning it with v6.17-rc7.

The ultimate goal is to synchronize all longterm branches so that they
include the full set of minmax.h changes.

The key motivation is to bring in commit d03eba99f5bf ("minmax: allow
min()/max()/clamp() if the arguments have the same signedness"), which
is missing in older kernels.

In mainline, this change enables min()/max()/clamp() to accept mixed
argument types, provided both have the same signedness. Without it,
backported patches that use these forms may trigger compiler warnings,
which escalate to build failures when -Werror is enabled.

Changes between v1 and v2:
- v1 included 15 patches:
  https://lore.kernel.org/stable/20250922103241.16213-1-farbere@amazon.com/T/#t
- First 3 were pushed to the stable-tree.
- 4th cauded amd driver's build to fail.
- This change fixes it.
- Modified files:
   drivers/gpu/drm/amd/amdgpu/amdgpu.h
   drivers/gpu/drm/amd/pm/swsmu/smu11/sienna_cichlid_ppt.c
   drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_0_ppt.c
   drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c

David Laight (7):
  minmax.h: add whitespace around operators and after commas
  minmax.h: update some comments
  minmax.h: reduce the #define expansion of min(), max() and clamp()
  minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp()
  minmax.h: move all the clamp() definitions after the min/max() ones
  minmax.h: simplify the variants of clamp()
  minmax.h: remove some #defines that are only expanded once

Linus Torvalds (5):
  minmax: make generic MIN() and MAX() macros available everywhere
  minmax: simplify min()/max()/clamp() implementation
  minmax: don't use max() in situations that want a C constant
    expression
  minmax: improve macro expansion and type checking
  minmax: fix up min3() and max3() too

 arch/um/drivers/mconsole_user.c               |   2 +
 drivers/edac/skx_common.h                     |   1 -
 drivers/gpu/drm/amd/amdgpu/amdgpu.h           |   2 +
 .../drm/amd/display/modules/hdcp/hdcp_ddc.c   |   2 +
 .../drm/amd/pm/powerplay/hwmgr/ppevvmath.h    |  14 +-
 .../amd/pm/swsmu/smu11/sienna_cichlid_ppt.c   |   2 +
 .../drm/amd/pm/swsmu/smu13/smu_v13_0_0_ppt.c  |   3 +
 .../drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c  |   3 +
 drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c        |   2 +-
 drivers/gpu/drm/radeon/evergreen_cs.c         |   2 +
 drivers/hwmon/adt7475.c                       |  24 +-
 drivers/input/touchscreen/cyttsp4_core.c      |   2 +-
 drivers/irqchip/irq-sun6i-r.c                 |   2 +-
 drivers/media/dvb-frontends/stv0367_priv.h    |   3 +
 .../net/can/usb/etas_es58x/es58x_devlink.c    |   2 +-
 drivers/net/fjes/fjes_main.c                  |   4 +-
 drivers/nfc/pn544/i2c.c                       |   2 -
 drivers/platform/x86/sony-laptop.c            |   1 -
 drivers/scsi/isci/init.c                      |   6 +-
 .../pci/hive_isp_css_include/math_support.h   |   5 -
 fs/btrfs/tree-checker.c                       |   2 +-
 include/linux/compiler.h                      |   9 +
 include/linux/minmax.h                        | 220 ++++++++++--------
 kernel/trace/preemptirq_delay_test.c          |   2 -
 lib/btree.c                                   |   1 -
 lib/decompress_unlzma.c                       |   2 +
 lib/vsprintf.c                                |   2 +-
 mm/zsmalloc.c                                 |   2 -
 tools/testing/selftests/mm/mremap_test.c      |   2 +
 tools/testing/selftests/seccomp/seccomp_bpf.c |   2 +
 30 files changed, 192 insertions(+), 136 deletions(-)

-- 
2.47.3

[PATCH v2 01/12 6.6.y] minmax: make generic MIN() and MAX() macros available everywhere

[Eliav Farber]

From: Linus Torvalds <torvalds@linux-foundation.org>

[ Upstream commit 1a251f52cfdc417c84411a056bc142cbd77baef4 ]

This just standardizes the use of MIN() and MAX() macros, with the very
traditional semantics.  The goal is to use these for C constant
expressions and for top-level / static initializers, and so be able to
simplify the min()/max() macros.

These macro names were used by various kernel code - they are very
traditional, after all - and all such users have been fixed up, with a
few different approaches:

 - trivial duplicated macro definitions have been removed

   Note that 'trivial' here means that it's obviously kernel code that
   already included all the major kernel headers, and thus gets the new
   generic MIN/MAX macros automatically.

 - non-trivial duplicated macro definitions are guarded with #ifndef

   This is the "yes, they define their own versions, but no, the include
   situation is not entirely obvious, and maybe they don't get the
   generic version automatically" case.

 - strange use case #1

   A couple of drivers decided that the way they want to describe their
   versioning is with

	#define MAJ 1
	#define MIN 2
	#define DRV_VERSION __stringify(MAJ) "." __stringify(MIN)

   which adds zero value and I just did my Alexander the Great
   impersonation, and rewrote that pointless Gordian knot as

	#define DRV_VERSION "1.2"

   instead.

 - strange use case #2

   A couple of drivers thought that it's a good idea to have a random
   'MIN' or 'MAX' define for a value or index into a table, rather than
   the traditional macro that takes arguments.

   These values were re-written as C enum's instead. The new
   function-line macros only expand when followed by an open
   parenthesis, and thus don't clash with enum use.

Happily, there weren't really all that many of these cases, and a lot of
users already had the pattern of using '#ifndef' guarding (or in one
case just using '#undef MIN') before defining their own private version
that does the same thing. I left such cases alone.

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>
---
v2:
  - Add missing #ifndef guards around MIN/MAX macro definitions
    to avoid redefinition errors in:
      * drivers/gpu/drm/amd/amdgpu/amdgpu.h
      * drivers/gpu/drm/amd/pm/swsmu/smu11/sienna_cichlid_ppt.c
      * drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_0_ppt.c
      * drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c

 arch/um/drivers/mconsole_user.c               |  2 ++
 drivers/edac/skx_common.h                     |  1 -
 drivers/gpu/drm/amd/amdgpu/amdgpu.h           |  2 ++
 .../drm/amd/display/modules/hdcp/hdcp_ddc.c   |  2 ++
 .../drm/amd/pm/powerplay/hwmgr/ppevvmath.h    | 14 +++++++----
 .../amd/pm/swsmu/smu11/sienna_cichlid_ppt.c   |  2 ++
 .../drm/amd/pm/swsmu/smu13/smu_v13_0_0_ppt.c  |  3 +++
 .../drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c  |  3 +++
 drivers/gpu/drm/radeon/evergreen_cs.c         |  2 ++
 drivers/hwmon/adt7475.c                       | 24 +++++++++----------
 drivers/media/dvb-frontends/stv0367_priv.h    |  3 +++
 drivers/net/fjes/fjes_main.c                  |  4 +---
 drivers/nfc/pn544/i2c.c                       |  2 --
 drivers/platform/x86/sony-laptop.c            |  1 -
 drivers/scsi/isci/init.c                      |  6 +----
 .../pci/hive_isp_css_include/math_support.h   |  5 ----
 include/linux/minmax.h                        |  2 ++
 kernel/trace/preemptirq_delay_test.c          |  2 --
 lib/btree.c                                   |  1 -
 lib/decompress_unlzma.c                       |  2 ++
 mm/zsmalloc.c                                 |  2 --
 tools/testing/selftests/mm/mremap_test.c      |  2 ++
 tools/testing/selftests/seccomp/seccomp_bpf.c |  2 ++
 23 files changed, 51 insertions(+), 38 deletions(-)

diff --git a/arch/um/drivers/mconsole_user.c b/arch/um/drivers/mconsole_user.c
index e24298a734be..a04cd13c6315 100644
--- a/arch/um/drivers/mconsole_user.c
+++ b/arch/um/drivers/mconsole_user.c
@@ -71,7 +71,9 @@ static struct mconsole_command *mconsole_parse(struct mc_request *req)
 	return NULL;
 }
 
+#ifndef MIN
 #define MIN(a,b) ((a)<(b) ? (a):(b))
+#endif
 
 #define STRINGX(x) #x
 #define STRING(x) STRINGX(x)
diff --git a/drivers/edac/skx_common.h b/drivers/edac/skx_common.h
index 2ea4d1d1fbef..1fa31a6fdfcd 100644
--- a/drivers/edac/skx_common.h
+++ b/drivers/edac/skx_common.h
@@ -45,7 +45,6 @@
 #define I10NM_NUM_CHANNELS	MAX(I10NM_NUM_DDR_CHANNELS, I10NM_NUM_HBM_CHANNELS)
 #define I10NM_NUM_DIMMS		MAX(I10NM_NUM_DDR_DIMMS, I10NM_NUM_HBM_DIMMS)
 
-#define MAX(a, b)	((a) > (b) ? (a) : (b))
 #define NUM_IMC		MAX(SKX_NUM_IMC, I10NM_NUM_IMC)
 #define NUM_CHANNELS	MAX(SKX_NUM_CHANNELS, I10NM_NUM_CHANNELS)
 #define NUM_DIMMS	MAX(SKX_NUM_DIMMS, I10NM_NUM_DIMMS)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index c5d706a4c7b4..78426f8c5420 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1285,7 +1285,9 @@ int emu_soc_asic_init(struct amdgpu_device *adev);
 	for (i = ffs(inst_mask); i-- != 0; \
 	     i = ffs(inst_mask & BIT_MASK_UPPER(i + 1)))
 
+#ifndef MIN
 #define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
+#endif
 
 /* Common functions */
 bool amdgpu_device_has_job_running(struct amdgpu_device *adev);
diff --git a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c
index 1b2df97226a3..40286e8dd4e1 100644
--- a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c
+++ b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c
@@ -25,7 +25,9 @@
 
 #include "hdcp.h"
 
+#ifndef MIN
 #define MIN(a, b) ((a) < (b) ? (a) : (b))
+#endif
 #define HDCP_I2C_ADDR 0x3a	/* 0x74 >> 1*/
 #define KSV_READ_SIZE 0xf	/* 0x6803b - 0x6802c */
 #define HDCP_MAX_AUX_TRANSACTION_SIZE 16
diff --git a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/ppevvmath.h b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/ppevvmath.h
index 6f54c410c2f9..409aeec6baa9 100644
--- a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/ppevvmath.h
+++ b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/ppevvmath.h
@@ -22,12 +22,18 @@
  */
 #include <asm/div64.h>
 
-#define SHIFT_AMOUNT 16 /* We multiply all original integers with 2^SHIFT_AMOUNT to get the fInt representation */
+enum ppevvmath_constants {
+	/* We multiply all original integers with 2^SHIFT_AMOUNT to get the fInt representation */
+	SHIFT_AMOUNT	= 16,
 
-#define PRECISION 5 /* Change this value to change the number of decimal places in the final output - 5 is a good default */
+	/* Change this value to change the number of decimal places in the final output - 5 is a good default */
+	PRECISION	=  5,
 
-#define SHIFTED_2 (2 << SHIFT_AMOUNT)
-#define MAX (1 << (SHIFT_AMOUNT - 1)) - 1 /* 32767 - Might change in the future */
+	SHIFTED_2	= (2 << SHIFT_AMOUNT),
+
+	/* 32767 - Might change in the future */
+	MAX		= (1 << (SHIFT_AMOUNT - 1)) - 1,
+};
 
 /* -------------------------------------------------------------------------------
  * NEW TYPE - fINT
diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu11/sienna_cichlid_ppt.c b/drivers/gpu/drm/amd/pm/swsmu/smu11/sienna_cichlid_ppt.c
index a7f4f82d23b4..2fdb982e70ef 100644
--- a/drivers/gpu/drm/amd/pm/swsmu/smu11/sienna_cichlid_ppt.c
+++ b/drivers/gpu/drm/amd/pm/swsmu/smu11/sienna_cichlid_ppt.c
@@ -2082,7 +2082,9 @@ static int sienna_cichlid_display_disable_memory_clock_switch(struct smu_context
 	return ret;
 }
 
+#ifndef MAX
 #define MAX(a, b)	((a) > (b) ? (a) : (b))
+#endif
 
 static int sienna_cichlid_update_pcie_parameters(struct smu_context *smu,
 						 uint8_t pcie_gen_cap,
diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_0_ppt.c b/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_0_ppt.c
index 4022dd44ebb2..fe6c42a736d0 100644
--- a/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_0_ppt.c
+++ b/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_0_ppt.c
@@ -1696,7 +1696,10 @@ static int smu_v13_0_0_get_thermal_temperature_range(struct smu_context *smu,
 	return 0;
 }
 
+#ifndef MAX
 #define MAX(a, b)	((a) > (b) ? (a) : (b))
+#endif
+
 static ssize_t smu_v13_0_0_get_gpu_metrics(struct smu_context *smu,
 					   void **table)
 {
diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c b/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c
index e1521d3a5e0c..df99d185cf8e 100644
--- a/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c
+++ b/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c
@@ -1674,7 +1674,10 @@ static int smu_v13_0_7_get_thermal_temperature_range(struct smu_context *smu,
 	return 0;
 }
 
+#ifndef MAX
 #define MAX(a, b)	((a) > (b) ? (a) : (b))
+#endif
+
 static ssize_t smu_v13_0_7_get_gpu_metrics(struct smu_context *smu,
 					   void **table)
 {
diff --git a/drivers/gpu/drm/radeon/evergreen_cs.c b/drivers/gpu/drm/radeon/evergreen_cs.c
index 820c2c3641d3..1311f10fad66 100644
--- a/drivers/gpu/drm/radeon/evergreen_cs.c
+++ b/drivers/gpu/drm/radeon/evergreen_cs.c
@@ -33,8 +33,10 @@
 #include "evergreen_reg_safe.h"
 #include "cayman_reg_safe.h"
 
+#ifndef MIN
 #define MAX(a,b)                   (((a)>(b))?(a):(b))
 #define MIN(a,b)                   (((a)<(b))?(a):(b))
+#endif
 
 #define REG_SAFE_BM_SIZE ARRAY_SIZE(evergreen_reg_safe_bm)
 
diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c
index 14b2547adae8..ce0ab4e4e41a 100644
--- a/drivers/hwmon/adt7475.c
+++ b/drivers/hwmon/adt7475.c
@@ -22,23 +22,23 @@
 #include <linux/util_macros.h>
 
 /* Indexes for the sysfs hooks */
-
-#define INPUT		0
-#define MIN		1
-#define MAX		2
-#define CONTROL		3
-#define OFFSET		3
-#define AUTOMIN		4
-#define THERM		5
-#define HYSTERSIS	6
-
+enum adt_sysfs_id {
+	INPUT		= 0,
+	MIN		= 1,
+	MAX		= 2,
+	CONTROL		= 3,
+	OFFSET		= 3,	// Dup
+	AUTOMIN		= 4,
+	THERM		= 5,
+	HYSTERSIS	= 6,
 /*
  * These are unique identifiers for the sysfs functions - unlike the
  * numbers above, these are not also indexes into an array
  */
+	ALARM		= 9,
+	FAULT		= 10,
+};
 
-#define ALARM		9
-#define FAULT		10
 
 /* 7475 Common Registers */
 
diff --git a/drivers/media/dvb-frontends/stv0367_priv.h b/drivers/media/dvb-frontends/stv0367_priv.h
index 617f605947b2..7f056d1cce82 100644
--- a/drivers/media/dvb-frontends/stv0367_priv.h
+++ b/drivers/media/dvb-frontends/stv0367_priv.h
@@ -25,8 +25,11 @@
 #endif
 
 /* MACRO definitions */
+#ifndef MIN
 #define MAX(X, Y) ((X) >= (Y) ? (X) : (Y))
 #define MIN(X, Y) ((X) <= (Y) ? (X) : (Y))
+#endif
+
 #define INRANGE(X, Y, Z) \
 	((((X) <= (Y)) && ((Y) <= (Z))) || \
 	(((Z) <= (Y)) && ((Y) <= (X))) ? 1 : 0)
diff --git a/drivers/net/fjes/fjes_main.c b/drivers/net/fjes/fjes_main.c
index 2513be6d4e11..cfcf0f7d9d90 100644
--- a/drivers/net/fjes/fjes_main.c
+++ b/drivers/net/fjes/fjes_main.c
@@ -14,9 +14,7 @@
 #include "fjes.h"
 #include "fjes_trace.h"
 
-#define MAJ 1
-#define MIN 2
-#define DRV_VERSION __stringify(MAJ) "." __stringify(MIN)
+#define DRV_VERSION "1.2"
 #define DRV_NAME	"fjes"
 char fjes_driver_name[] = DRV_NAME;
 char fjes_driver_version[] = DRV_VERSION;
diff --git a/drivers/nfc/pn544/i2c.c b/drivers/nfc/pn544/i2c.c
index 3f6d74832bac..be566ca7bae9 100644
--- a/drivers/nfc/pn544/i2c.c
+++ b/drivers/nfc/pn544/i2c.c
@@ -126,8 +126,6 @@ struct pn544_i2c_fw_secure_blob {
 #define PN544_FW_CMD_RESULT_COMMAND_REJECTED 0xE0
 #define PN544_FW_CMD_RESULT_CHUNK_ERROR 0xE6
 
-#define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
-
 #define PN544_FW_WRITE_BUFFER_MAX_LEN 0x9f7
 #define PN544_FW_I2C_MAX_PAYLOAD PN544_HCI_I2C_LLC_MAX_SIZE
 #define PN544_FW_I2C_WRITE_FRAME_HEADER_LEN 8
diff --git a/drivers/platform/x86/sony-laptop.c b/drivers/platform/x86/sony-laptop.c
index 9569f11dec8c..bd7323cf9a97 100644
--- a/drivers/platform/x86/sony-laptop.c
+++ b/drivers/platform/x86/sony-laptop.c
@@ -757,7 +757,6 @@ static union acpi_object *__call_snc_method(acpi_handle handle, char *method,
 	return result;
 }
 
-#define MIN(a, b)	(a > b ? b : a)
 static int sony_nc_buffer_call(acpi_handle handle, char *name, u64 *value,
 		void *buffer, size_t buflen)
 {
diff --git a/drivers/scsi/isci/init.c b/drivers/scsi/isci/init.c
index 6277162a028b..6eefa7e5f4cf 100644
--- a/drivers/scsi/isci/init.c
+++ b/drivers/scsi/isci/init.c
@@ -65,11 +65,7 @@
 #include "task.h"
 #include "probe_roms.h"
 
-#define MAJ 1
-#define MIN 2
-#define BUILD 0
-#define DRV_VERSION __stringify(MAJ) "." __stringify(MIN) "." \
-	__stringify(BUILD)
+#define DRV_VERSION "1.2.0"
 
 MODULE_VERSION(DRV_VERSION);
 
diff --git a/drivers/staging/media/atomisp/pci/hive_isp_css_include/math_support.h b/drivers/staging/media/atomisp/pci/hive_isp_css_include/math_support.h
index a444ec14ff9d..1c17a87a8572 100644
--- a/drivers/staging/media/atomisp/pci/hive_isp_css_include/math_support.h
+++ b/drivers/staging/media/atomisp/pci/hive_isp_css_include/math_support.h
@@ -31,11 +31,6 @@
 /* A => B */
 #define IMPLIES(a, b)        (!(a) || (b))
 
-/* for preprocessor and array sizing use MIN and MAX
-   otherwise use min and max */
-#define MAX(a, b)            (((a) > (b)) ? (a) : (b))
-#define MIN(a, b)            (((a) < (b)) ? (a) : (b))
-
 #define ROUND_DIV(a, b)      (((b) != 0) ? ((a) + ((b) >> 1)) / (b) : 0)
 #define CEIL_DIV(a, b)       (((b) != 0) ? ((a) + (b) - 1) / (b) : 0)
 #define CEIL_MUL(a, b)       (CEIL_DIV(a, b) * (b))
diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 9c2848abc804..fc384714da45 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -277,6 +277,8 @@ static inline bool in_range32(u32 val, u32 start, u32 len)
  * Use these carefully: no type checking, and uses the arguments
  * multiple times. Use for obvious constants only.
  */
+#define MIN(a,b) __cmp(min,a,b)
+#define MAX(a,b) __cmp(max,a,b)
 #define MIN_T(type,a,b) __cmp(min,(type)(a),(type)(b))
 #define MAX_T(type,a,b) __cmp(max,(type)(a),(type)(b))
 
diff --git a/kernel/trace/preemptirq_delay_test.c b/kernel/trace/preemptirq_delay_test.c
index 8af92dbe98f0..acb0c971a408 100644
--- a/kernel/trace/preemptirq_delay_test.c
+++ b/kernel/trace/preemptirq_delay_test.c
@@ -34,8 +34,6 @@ MODULE_PARM_DESC(cpu_affinity, "Cpu num test is running on");
 
 static struct completion done;
 
-#define MIN(x, y) ((x) < (y) ? (x) : (y))
-
 static void busy_wait(ulong time)
 {
 	u64 start, end;
diff --git a/lib/btree.c b/lib/btree.c
index 49420cae3a83..bb81d3393ac5 100644
--- a/lib/btree.c
+++ b/lib/btree.c
@@ -43,7 +43,6 @@
 #include <linux/slab.h>
 #include <linux/module.h>
 
-#define MAX(a, b) ((a) > (b) ? (a) : (b))
 #define NODESIZE MAX(L1_CACHE_BYTES, 128)
 
 struct btree_geo {
diff --git a/lib/decompress_unlzma.c b/lib/decompress_unlzma.c
index 20a858031f12..9d34d35908da 100644
--- a/lib/decompress_unlzma.c
+++ b/lib/decompress_unlzma.c
@@ -37,7 +37,9 @@
 
 #include <linux/decompress/mm.h>
 
+#ifndef MIN
 #define	MIN(a, b) (((a) < (b)) ? (a) : (b))
+#endif
 
 static long long INIT read_int(unsigned char *ptr, int size)
 {
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index c82070167d8a..14327fc34aa7 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -119,8 +119,6 @@
 #define ISOLATED_BITS	5
 #define MAGIC_VAL_BITS	8
 
-#define MAX(a, b) ((a) >= (b) ? (a) : (b))
-
 #define ZS_MAX_PAGES_PER_ZSPAGE	(_AC(CONFIG_ZSMALLOC_CHAIN_SIZE, UL))
 
 /* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
diff --git a/tools/testing/selftests/mm/mremap_test.c b/tools/testing/selftests/mm/mremap_test.c
index 5c3773de9f0f..944645f9d2b3 100644
--- a/tools/testing/selftests/mm/mremap_test.c
+++ b/tools/testing/selftests/mm/mremap_test.c
@@ -22,7 +22,9 @@
 #define VALIDATION_DEFAULT_THRESHOLD 4	/* 4MB */
 #define VALIDATION_NO_THRESHOLD 0	/* Verify the entire region */
 
+#ifndef MIN
 #define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
+#endif
 
 struct config {
 	unsigned long long src_alignment;
diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index 15325ca35f1e..4390965c84c4 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -60,7 +60,9 @@
 #define SKIP(s, ...)	XFAIL(s, ##__VA_ARGS__)
 #endif
 
+#ifndef MIN
 #define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
+#endif
 
 #ifndef PR_SET_PTRACER
 # define PR_SET_PTRACER 0x59616d61
-- 
2.47.3

[PATCH v2 02/12 6.6.y] minmax: simplify min()/max()/clamp() implementation

[Eliav Farber]

From: Linus Torvalds <torvalds@linux-foundation.org>

[ Upstream commit dc1c8034e31b14a2e5e212104ec508aec44ce1b9 ]

Now that we no longer have any C constant expression contexts (ie array
size declarations or static initializers) that use min() or max(), we
can simpify the implementation by not having to worry about the result
staying as a C constant expression.

So now we can unconditionally just use temporary variables of the right
type, and get rid of the excessive expansion that used to come from the
use of

   __builtin_choose_expr(__is_constexpr(...), ..

to pick the specialized code for constant expressions.

Another expansion simplification is to pass the temporary variables (in
addition to the original expression) to our __types_ok() macro.  That
may superficially look like it complicates the macro, but when we only
want the type of the expression, expanding the temporary variable names
is much simpler and smaller than expanding the potentially complicated
original expression.

As a result, on my machine, doing a

  $ time make drivers/staging/media/atomisp/pci/isp/kernels/ynr/ynr_1.0/ia_css_ynr.host.i

goes from

	real	0m16.621s
	user	0m15.360s
	sys	0m1.221s

to

	real	0m2.532s
	user	0m2.091s
	sys	0m0.452s

because the token expansion goes down dramatically.

In particular, the longest line expansion (which was line 71 of that
'ia_css_ynr.host.c' file) shrinks from 23,338kB (yes, 23MB for one
single line) to "just" 1,444kB (now "only" 1.4MB).

And yes, that line is still the line from hell, because it's doing
multiple levels of "min()/max()" expansion thanks to some of them being
hidden inside the uDIGIT_FITTING() macro.

Lorenzo has a nice cleanup patch that makes that driver use inline
functions instead of macros for sDIGIT_FITTING() and uDIGIT_FITTING(),
which will fix that line once and for all, but the 16-fold reduction in
this case does show why we need to simplify these helpers.

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>
---
 include/linux/minmax.h | 43 ++++++++++++++++++++----------------------
 1 file changed, 20 insertions(+), 23 deletions(-)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index fc384714da45..e3e4353df983 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -35,10 +35,10 @@
 #define __is_noneg_int(x)	\
 	(__builtin_choose_expr(__is_constexpr(x) && __is_signed(x), x, -1) >= 0)
 
-#define __types_ok(x, y) 					\
-	(__is_signed(x) == __is_signed(y) ||			\
-		__is_signed((x) + 0) == __is_signed((y) + 0) ||	\
-		__is_noneg_int(x) || __is_noneg_int(y))
+#define __types_ok(x, y, ux, uy) 				\
+	(__is_signed(ux) == __is_signed(uy) ||			\
+	 __is_signed((ux) + 0) == __is_signed((uy) + 0) ||	\
+	 __is_noneg_int(x) || __is_noneg_int(y))
 
 #define __cmp_op_min <
 #define __cmp_op_max >
@@ -51,34 +51,31 @@
 #define __cmp_once(op, type, x, y) \
 	__cmp_once_unique(op, type, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
 
-#define __careful_cmp_once(op, x, y) ({			\
-	static_assert(__types_ok(x, y),			\
+#define __careful_cmp_once(op, x, y, ux, uy) ({		\
+	__auto_type ux = (x); __auto_type uy = (y);	\
+	static_assert(__types_ok(x, y, ux, uy),		\
 		#op "(" #x ", " #y ") signedness error, fix types or consider u" #op "() before " #op "_t()"); \
-	__cmp_once(op, __auto_type, x, y); })
+	__cmp(op, ux, uy); })
 
-#define __careful_cmp(op, x, y)					\
-	__builtin_choose_expr(__is_constexpr((x) - (y)),	\
-		__cmp(op, x, y), __careful_cmp_once(op, x, y))
+#define __careful_cmp(op, x, y) \
+	__careful_cmp_once(op, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
 
 #define __clamp(val, lo, hi)	\
 	((val) >= (hi) ? (hi) : ((val) <= (lo) ? (lo) : (val)))
 
-#define __clamp_once(val, lo, hi, unique_val, unique_lo, unique_hi) ({		\
-	typeof(val) unique_val = (val);						\
-	typeof(lo) unique_lo = (lo);						\
-	typeof(hi) unique_hi = (hi);						\
+#define __clamp_once(val, lo, hi, uval, ulo, uhi) ({				\
+	__auto_type uval = (val);						\
+	__auto_type ulo = (lo);							\
+	__auto_type uhi = (hi);							\
 	static_assert(__builtin_choose_expr(__is_constexpr((lo) > (hi)), 	\
 			(lo) <= (hi), true),					\
 		"clamp() low limit " #lo " greater than high limit " #hi);	\
-	static_assert(__types_ok(val, lo), "clamp() 'lo' signedness error");	\
-	static_assert(__types_ok(val, hi), "clamp() 'hi' signedness error");	\
-	__clamp(unique_val, unique_lo, unique_hi); })
-
-#define __careful_clamp(val, lo, hi) ({					\
-	__builtin_choose_expr(__is_constexpr((val) - (lo) + (hi)),	\
-		__clamp(val, lo, hi),					\
-		__clamp_once(val, lo, hi, __UNIQUE_ID(__val),		\
-			     __UNIQUE_ID(__lo), __UNIQUE_ID(__hi))); })
+	static_assert(__types_ok(uval, lo, uval, ulo), "clamp() 'lo' signedness error");	\
+	static_assert(__types_ok(uval, hi, uval, uhi), "clamp() 'hi' signedness error");	\
+	__clamp(uval, ulo, uhi); })
+
+#define __careful_clamp(val, lo, hi) \
+	__clamp_once(val, lo, hi, __UNIQUE_ID(v_), __UNIQUE_ID(l_), __UNIQUE_ID(h_))
 
 /**
  * min - return minimum of two values of the same or compatible types
-- 
2.47.3

[PATCH v2 03/12 6.6.y] minmax: don't use max() in situations that want a C constant expression

[Eliav Farber]

From: Linus Torvalds <torvalds@linux-foundation.org>

[ Upstream commit cb04e8b1d2f24c4c2c92f7b7529031fc35a16fed ]

We only had a couple of array[] declarations, and changing them to just
use 'MAX()' instead of 'max()' fixes the issue.

This will allow us to simplify our min/max macros enormously, since they
can now unconditionally use temporary variables to avoid using the
argument values multiple times.

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>
---
 drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c         | 2 +-
 drivers/input/touchscreen/cyttsp4_core.c       | 2 +-
 drivers/irqchip/irq-sun6i-r.c                  | 2 +-
 drivers/net/can/usb/etas_es58x/es58x_devlink.c | 2 +-
 fs/btrfs/tree-checker.c                        | 2 +-
 lib/vsprintf.c                                 | 2 +-
 6 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c b/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
index 12618a583e97..c1962f1974c6 100644
--- a/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
+++ b/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
@@ -708,7 +708,7 @@ static const char *smu_get_feature_name(struct smu_context *smu,
 size_t smu_cmn_get_pp_feature_mask(struct smu_context *smu,
 				   char *buf)
 {
-	int8_t sort_feature[max(SMU_FEATURE_COUNT, SMU_FEATURE_MAX)];
+	int8_t sort_feature[MAX(SMU_FEATURE_COUNT, SMU_FEATURE_MAX)];
 	uint64_t feature_mask;
 	int i, feature_index;
 	uint32_t count = 0;
diff --git a/drivers/input/touchscreen/cyttsp4_core.c b/drivers/input/touchscreen/cyttsp4_core.c
index 7cb26929dc73..9dc25eb2be44 100644
--- a/drivers/input/touchscreen/cyttsp4_core.c
+++ b/drivers/input/touchscreen/cyttsp4_core.c
@@ -871,7 +871,7 @@ static void cyttsp4_get_mt_touches(struct cyttsp4_mt_data *md, int num_cur_tch)
 	struct cyttsp4_touch tch;
 	int sig;
 	int i, j, t = 0;
-	int ids[max(CY_TMA1036_MAX_TCH, CY_TMA4XX_MAX_TCH)];
+	int ids[MAX(CY_TMA1036_MAX_TCH, CY_TMA4XX_MAX_TCH)];
 
 	memset(ids, 0, si->si_ofs.tch_abs[CY_TCH_T].max * sizeof(int));
 	for (i = 0; i < num_cur_tch; i++) {
diff --git a/drivers/irqchip/irq-sun6i-r.c b/drivers/irqchip/irq-sun6i-r.c
index a01e44049415..99958d470d62 100644
--- a/drivers/irqchip/irq-sun6i-r.c
+++ b/drivers/irqchip/irq-sun6i-r.c
@@ -270,7 +270,7 @@ static const struct irq_domain_ops sun6i_r_intc_domain_ops = {
 
 static int sun6i_r_intc_suspend(void)
 {
-	u32 buf[BITS_TO_U32(max(SUN6I_NR_TOP_LEVEL_IRQS, SUN6I_NR_MUX_BITS))];
+	u32 buf[BITS_TO_U32(MAX(SUN6I_NR_TOP_LEVEL_IRQS, SUN6I_NR_MUX_BITS))];
 	int i;
 
 	/* Wake IRQs are enabled during system sleep and shutdown. */
diff --git a/drivers/net/can/usb/etas_es58x/es58x_devlink.c b/drivers/net/can/usb/etas_es58x/es58x_devlink.c
index e763a9904bed..0d155eb1b9e9 100644
--- a/drivers/net/can/usb/etas_es58x/es58x_devlink.c
+++ b/drivers/net/can/usb/etas_es58x/es58x_devlink.c
@@ -215,7 +215,7 @@ static int es58x_devlink_info_get(struct devlink *devlink,
 	struct es58x_sw_version *fw_ver = &es58x_dev->firmware_version;
 	struct es58x_sw_version *bl_ver = &es58x_dev->bootloader_version;
 	struct es58x_hw_revision *hw_rev = &es58x_dev->hardware_revision;
-	char buf[max(sizeof("xx.xx.xx"), sizeof("axxx/xxx"))];
+	char buf[MAX(sizeof("xx.xx.xx"), sizeof("axxx/xxx"))];
 	int ret = 0;
 
 	if (es58x_sw_version_is_valid(fw_ver)) {
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 6d16506bbdc0..6f4c42e66519 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -614,7 +614,7 @@ static int check_dir_item(struct extent_buffer *leaf,
 		 */
 		if (key->type == BTRFS_DIR_ITEM_KEY ||
 		    key->type == BTRFS_XATTR_ITEM_KEY) {
-			char namebuf[max(BTRFS_NAME_LEN, XATTR_NAME_MAX)];
+			char namebuf[MAX(BTRFS_NAME_LEN, XATTR_NAME_MAX)];
 
 			read_extent_buffer(leaf, namebuf,
 					(unsigned long)(di + 1), name_len);
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 2aa408441cd3..f4ab2750cfc1 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1079,7 +1079,7 @@ char *resource_string(char *buf, char *end, struct resource *res,
 #define FLAG_BUF_SIZE		(2 * sizeof(res->flags))
 #define DECODED_BUF_SIZE	sizeof("[mem - 64bit pref window disabled]")
 #define RAW_BUF_SIZE		sizeof("[mem - flags 0x]")
-	char sym[max(2*RSRC_BUF_SIZE + DECODED_BUF_SIZE,
+	char sym[MAX(2*RSRC_BUF_SIZE + DECODED_BUF_SIZE,
 		     2*RSRC_BUF_SIZE + FLAG_BUF_SIZE + RAW_BUF_SIZE)];
 
 	char *p = sym, *pend = sym + sizeof(sym);
-- 
2.47.3

[PATCH v2 04/12 6.6.y] minmax: improve macro expansion and type checking

[Eliav Farber]

From: Linus Torvalds <torvalds@linux-foundation.org>

[ Upstream commit 22f5468731491e53356ba7c028f0fdea20b18e2c ]

This clarifies the rules for min()/max()/clamp() type checking and makes
them a much more efficient macro expansion.

In particular, we now look at the type and range of the inputs to see
whether they work together, generating a mask of acceptable comparisons,
and then just verifying that the inputs have a shared case:

 - an expression with a signed type can be used for
    (1) signed comparisons
    (2) unsigned comparisons if it is statically known to have a
        non-negative value

 - an expression with an unsigned type can be used for
    (3) unsigned comparison
    (4) signed comparisons if the type is smaller than 'int' and thus
        the C integer promotion rules will make it signed anyway

Here rule (1) and (3) are obvious, and rule (2) is important in order to
allow obvious trivial constants to be used together with unsigned
values.

Rule (4) is not necessarily a good idea, but matches what we used to do,
and we have extant cases of this situation in the kernel.  Notably with
bcachefs having an expression like

	min(bch2_bucket_sectors_dirty(a), ca->mi.bucket_size)

where bch2_bucket_sectors_dirty() returns an 's64', and
'ca->mi.bucket_size' is of type 'u16'.

Technically that bcachefs comparison is clearly sensible on a C type
level, because the 'u16' will go through the normal C integer promotion,
and become 'int', and then we're comparing two signed values and
everything looks sane.

However, it's not entirely clear that a 'min(s64,u16)' operation makes a
lot of conceptual sense, and it's possible that we will remove rule (4).
After all, the _reason_ we have these complicated type checks is exactly
that the C type promotion rules are not very intuitive.

But at least for now the rule is in place for backwards compatibility.

Also note that rule (2) existed before, but is hugely relaxed by this
commit.  It used to be true only for the simplest compile-time
non-negative integer constants.  The new macro model will allow cases
where the compiler can trivially see that an expression is non-negative
even if it isn't necessarily a constant.

For example, the amdgpu driver does

	min_t(size_t, sizeof(fru_info->serial), pia[addr] & 0x3F));

because our old 'min()' macro would see that 'pia[addr] & 0x3F' is of
type 'int' and clearly not a C constant expression, so doing a 'min()'
with a 'size_t' is a signedness violation.

Our new 'min()' macro still sees that 'pia[addr] & 0x3F' is of type
'int', but is smart enough to also see that it is clearly non-negative,
and thus would allow that case without any complaints.

Cc: Arnd Bergmann <arnd@kernel.org>
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>
---
 include/linux/compiler.h |  9 +++++
 include/linux/minmax.h   | 74 ++++++++++++++++++++++++++++++++--------
 2 files changed, 68 insertions(+), 15 deletions(-)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index e84ed3a43f1f..1d4f23ea3105 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -244,6 +244,15 @@ static inline void *offset_to_ptr(const int *off)
 #define is_signed_type(type) (((type)(-1)) < (__force type)1)
 #define is_unsigned_type(type) (!is_signed_type(type))
 
+/*
+ * Useful shorthand for "is this condition known at compile-time?"
+ *
+ * Note that the condition may involve non-constant values,
+ * but the compiler may know enough about the details of the
+ * values to determine that the condition is statically true.
+ */
+#define statically_true(x) (__builtin_constant_p(x) && (x))
+
 /*
  * This is needed in functions which generate the stack canary, see
  * arch/x86/kernel/smpboot.c::start_secondary() for an example.
diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index e3e4353df983..41da6f85a407 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -26,19 +26,63 @@
 #define __typecheck(x, y) \
 	(!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
 
-/* is_signed_type() isn't a constexpr for pointer types */
-#define __is_signed(x) 								\
-	__builtin_choose_expr(__is_constexpr(is_signed_type(typeof(x))),	\
-		is_signed_type(typeof(x)), 0)
+/*
+ * __sign_use for integer expressions:
+ *   bit #0 set if ok for unsigned comparisons
+ *   bit #1 set if ok for signed comparisons
+ *
+ * In particular, statically non-negative signed integer
+ * expressions are ok for both.
+ *
+ * NOTE! Unsigned types smaller than 'int' are implicitly
+ * converted to 'int' in expressions, and are accepted for
+ * signed conversions for now. This is debatable.
+ *
+ * Note that 'x' is the original expression, and 'ux' is
+ * the unique variable that contains the value.
+ *
+ * We use 'ux' for pure type checking, and 'x' for when
+ * we need to look at the value (but without evaluating
+ * it for side effects! Careful to only ever evaluate it
+ * with sizeof() or __builtin_constant_p() etc).
+ *
+ * Pointers end up being checked by the normal C type
+ * rules at the actual comparison, and these expressions
+ * only need to be careful to not cause warnings for
+ * pointer use.
+ */
+#define __signed_type_use(x,ux) (2+__is_nonneg(x,ux))
+#define __unsigned_type_use(x,ux) (1+2*(sizeof(ux)<4))
+#define __sign_use(x,ux) (is_signed_type(typeof(ux))? \
+	__signed_type_use(x,ux):__unsigned_type_use(x,ux))
+
+/*
+ * To avoid warnings about casting pointers to integers
+ * of different sizes, we need that special sign type.
+ *
+ * On 64-bit we can just always use 'long', since any
+ * integer or pointer type can just be cast to that.
+ *
+ * This does not work for 128-bit signed integers since
+ * the cast would truncate them, but we do not use s128
+ * types in the kernel (we do use 'u128', but they will
+ * be handled by the !is_signed_type() case).
+ *
+ * NOTE! The cast is there only to avoid any warnings
+ * from when values that aren't signed integer types.
+ */
+#ifdef CONFIG_64BIT
+  #define __signed_type(ux) long
+#else
+  #define __signed_type(ux) typeof(__builtin_choose_expr(sizeof(ux)>4,1LL,1L))
+#endif
+#define __is_nonneg(x,ux) statically_true((__signed_type(ux))(x)>=0)
 
-/* True for a non-negative signed int constant */
-#define __is_noneg_int(x)	\
-	(__builtin_choose_expr(__is_constexpr(x) && __is_signed(x), x, -1) >= 0)
+#define __types_ok(x,y,ux,uy) \
+	(__sign_use(x,ux) & __sign_use(y,uy))
 
-#define __types_ok(x, y, ux, uy) 				\
-	(__is_signed(ux) == __is_signed(uy) ||			\
-	 __is_signed((ux) + 0) == __is_signed((uy) + 0) ||	\
-	 __is_noneg_int(x) || __is_noneg_int(y))
+#define __types_ok3(x,y,z,ux,uy,uz) \
+	(__sign_use(x,ux) & __sign_use(y,uy) & __sign_use(z,uz))
 
 #define __cmp_op_min <
 #define __cmp_op_max >
@@ -53,8 +97,8 @@
 
 #define __careful_cmp_once(op, x, y, ux, uy) ({		\
 	__auto_type ux = (x); __auto_type uy = (y);	\
-	static_assert(__types_ok(x, y, ux, uy),		\
-		#op "(" #x ", " #y ") signedness error, fix types or consider u" #op "() before " #op "_t()"); \
+	BUILD_BUG_ON_MSG(!__types_ok(x,y,ux,uy),	\
+		#op"("#x", "#y") signedness error");	\
 	__cmp(op, ux, uy); })
 
 #define __careful_cmp(op, x, y) \
@@ -70,8 +114,8 @@
 	static_assert(__builtin_choose_expr(__is_constexpr((lo) > (hi)), 	\
 			(lo) <= (hi), true),					\
 		"clamp() low limit " #lo " greater than high limit " #hi);	\
-	static_assert(__types_ok(uval, lo, uval, ulo), "clamp() 'lo' signedness error");	\
-	static_assert(__types_ok(uval, hi, uval, uhi), "clamp() 'hi' signedness error");	\
+	BUILD_BUG_ON_MSG(!__types_ok3(val,lo,hi,uval,ulo,uhi),			\
+		"clamp("#val", "#lo", "#hi") signedness error");		\
 	__clamp(uval, ulo, uhi); })
 
 #define __careful_clamp(val, lo, hi) \
-- 
2.47.3

[PATCH v2 05/12 6.6.y] minmax: fix up min3() and max3() too

[Eliav Farber]

From: Linus Torvalds <torvalds@linux-foundation.org>

[ Upstream commit 21b136cc63d2a9ddd60d4699552b69c214b32964 ]

David Laight pointed out that we should deal with the min3() and max3()
mess too, which still does excessive expansion.

And our current macros are actually rather broken.

In particular, the macros did this:

  #define min3(x, y, z) min((typeof(x))min(x, y), z)
  #define max3(x, y, z) max((typeof(x))max(x, y), z)

and that not only is a nested expansion of possibly very complex
arguments with all that involves, the typing with that "typeof()" cast
is completely wrong.

For example, imagine what happens in max3() if 'x' happens to be a
'unsigned char', but 'y' and 'z' are 'unsigned long'.  The types are
compatible, and there's no warning - but the result is just random
garbage.

No, I don't think we've ever hit that issue in practice, but since we
now have sane infrastructure for doing this right, let's just use it.
It fixes any excessive expansion, and also avoids these kinds of broken
type issues.

Requested-by: David Laight <David.Laight@aculab.com>
Acked-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 include/linux/minmax.h | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 41da6f85a407..98008dd92153 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -152,13 +152,20 @@
 #define umax(x, y)	\
 	__careful_cmp(max, (x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull)
 
+#define __careful_op3(op, x, y, z, ux, uy, uz) ({			\
+	__auto_type ux = (x); __auto_type uy = (y);__auto_type uz = (z);\
+	BUILD_BUG_ON_MSG(!__types_ok3(x,y,z,ux,uy,uz),			\
+		#op"3("#x", "#y", "#z") signedness error");		\
+	__cmp(op, ux, __cmp(op, uy, uz)); })
+
 /**
  * min3 - return minimum of three values
  * @x: first value
  * @y: second value
  * @z: third value
  */
-#define min3(x, y, z) min((typeof(x))min(x, y), z)
+#define min3(x, y, z) \
+	__careful_op3(min, x, y, z, __UNIQUE_ID(x_), __UNIQUE_ID(y_), __UNIQUE_ID(z_))
 
 /**
  * max3 - return maximum of three values
@@ -166,7 +173,8 @@
  * @y: second value
  * @z: third value
  */
-#define max3(x, y, z) max((typeof(x))max(x, y), z)
+#define max3(x, y, z) \
+	__careful_op3(max, x, y, z, __UNIQUE_ID(x_), __UNIQUE_ID(y_), __UNIQUE_ID(z_))
 
 /**
  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
-- 
2.47.3

[PATCH v2 06/12 6.6.y] minmax.h: add whitespace around operators and after commas

[Eliav Farber]

From: David Laight <David.Laight@ACULAB.COM>

[ Upstream commit 71ee9b16251ea4bf7c1fe222517c82bdb3220acc ]

Patch series "minmax.h: Cleanups and minor optimisations".

Some tidyups and minor changes to minmax.h.

This patch (of 7):

Link: https://lkml.kernel.org/r/c50365d214e04f9ba256d417c8bebbc0@AcuMS.aculab.com
Link: https://lkml.kernel.org/r/f04b2e1310244f62826267346fde0553@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 include/linux/minmax.h | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 98008dd92153..51b0d988e322 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -51,10 +51,10 @@
  * only need to be careful to not cause warnings for
  * pointer use.
  */
-#define __signed_type_use(x,ux) (2+__is_nonneg(x,ux))
-#define __unsigned_type_use(x,ux) (1+2*(sizeof(ux)<4))
-#define __sign_use(x,ux) (is_signed_type(typeof(ux))? \
-	__signed_type_use(x,ux):__unsigned_type_use(x,ux))
+#define __signed_type_use(x, ux) (2 + __is_nonneg(x, ux))
+#define __unsigned_type_use(x, ux) (1 + 2 * (sizeof(ux) < 4))
+#define __sign_use(x, ux) (is_signed_type(typeof(ux)) ? \
+	__signed_type_use(x, ux) : __unsigned_type_use(x, ux))
 
 /*
  * To avoid warnings about casting pointers to integers
@@ -74,15 +74,15 @@
 #ifdef CONFIG_64BIT
   #define __signed_type(ux) long
 #else
-  #define __signed_type(ux) typeof(__builtin_choose_expr(sizeof(ux)>4,1LL,1L))
+  #define __signed_type(ux) typeof(__builtin_choose_expr(sizeof(ux) > 4, 1LL, 1L))
 #endif
-#define __is_nonneg(x,ux) statically_true((__signed_type(ux))(x)>=0)
+#define __is_nonneg(x, ux) statically_true((__signed_type(ux))(x) >= 0)
 
-#define __types_ok(x,y,ux,uy) \
-	(__sign_use(x,ux) & __sign_use(y,uy))
+#define __types_ok(x, y, ux, uy) \
+	(__sign_use(x, ux) & __sign_use(y, uy))
 
-#define __types_ok3(x,y,z,ux,uy,uz) \
-	(__sign_use(x,ux) & __sign_use(y,uy) & __sign_use(z,uz))
+#define __types_ok3(x, y, z, ux, uy, uz) \
+	(__sign_use(x, ux) & __sign_use(y, uy) & __sign_use(z, uz))
 
 #define __cmp_op_min <
 #define __cmp_op_max >
@@ -97,7 +97,7 @@
 
 #define __careful_cmp_once(op, x, y, ux, uy) ({		\
 	__auto_type ux = (x); __auto_type uy = (y);	\
-	BUILD_BUG_ON_MSG(!__types_ok(x,y,ux,uy),	\
+	BUILD_BUG_ON_MSG(!__types_ok(x, y, ux, uy),	\
 		#op"("#x", "#y") signedness error");	\
 	__cmp(op, ux, uy); })
 
@@ -114,7 +114,7 @@
 	static_assert(__builtin_choose_expr(__is_constexpr((lo) > (hi)), 	\
 			(lo) <= (hi), true),					\
 		"clamp() low limit " #lo " greater than high limit " #hi);	\
-	BUILD_BUG_ON_MSG(!__types_ok3(val,lo,hi,uval,ulo,uhi),			\
+	BUILD_BUG_ON_MSG(!__types_ok3(val, lo, hi, uval, ulo, uhi),		\
 		"clamp("#val", "#lo", "#hi") signedness error");		\
 	__clamp(uval, ulo, uhi); })
 
@@ -154,7 +154,7 @@
 
 #define __careful_op3(op, x, y, z, ux, uy, uz) ({			\
 	__auto_type ux = (x); __auto_type uy = (y);__auto_type uz = (z);\
-	BUILD_BUG_ON_MSG(!__types_ok3(x,y,z,ux,uy,uz),			\
+	BUILD_BUG_ON_MSG(!__types_ok3(x, y, z, ux, uy, uz),		\
 		#op"3("#x", "#y", "#z") signedness error");		\
 	__cmp(op, ux, __cmp(op, uy, uz)); })
 
@@ -326,9 +326,9 @@ static inline bool in_range32(u32 val, u32 start, u32 len)
  * Use these carefully: no type checking, and uses the arguments
  * multiple times. Use for obvious constants only.
  */
-#define MIN(a,b) __cmp(min,a,b)
-#define MAX(a,b) __cmp(max,a,b)
-#define MIN_T(type,a,b) __cmp(min,(type)(a),(type)(b))
-#define MAX_T(type,a,b) __cmp(max,(type)(a),(type)(b))
+#define MIN(a, b) __cmp(min, a, b)
+#define MAX(a, b) __cmp(max, a, b)
+#define MIN_T(type, a, b) __cmp(min, (type)(a), (type)(b))
+#define MAX_T(type, a, b) __cmp(max, (type)(a), (type)(b))
 
 #endif	/* _LINUX_MINMAX_H */
-- 
2.47.3

[PATCH v2 07/12 6.6.y] minmax.h: update some comments

[Eliav Farber]

From: David Laight <David.Laight@ACULAB.COM>

[ Upstream commit 10666e99204818ef45c702469488353b5bb09ec7 ]

- Change three to several.
- Remove the comment about retaining constant expressions, no longer true.
- Realign to nearer 80 columns and break on major punctiation.
- Add a leading comment to the block before __signed_type() and __is_nonneg()
  Otherwise the block explaining the cast is a bit 'floating'.
  Reword the rest of that comment to improve readability.

Link: https://lkml.kernel.org/r/85b050c81c1d4076aeb91a6cded45fee@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 include/linux/minmax.h | 53 +++++++++++++++++++-----------------------
 1 file changed, 24 insertions(+), 29 deletions(-)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 51b0d988e322..24e4b372649a 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -8,13 +8,10 @@
 #include <linux/types.h>
 
 /*
- * min()/max()/clamp() macros must accomplish three things:
+ * min()/max()/clamp() macros must accomplish several things:
  *
  * - Avoid multiple evaluations of the arguments (so side-effects like
  *   "x++" happen only once) when non-constant.
- * - Retain result as a constant expressions when called with only
- *   constant expressions (to avoid tripping VLA warnings in stack
- *   allocation usage).
  * - Perform signed v unsigned type-checking (to generate compile
  *   errors instead of nasty runtime surprises).
  * - Unsigned char/short are always promoted to signed int and can be
@@ -31,25 +28,23 @@
  *   bit #0 set if ok for unsigned comparisons
  *   bit #1 set if ok for signed comparisons
  *
- * In particular, statically non-negative signed integer
- * expressions are ok for both.
+ * In particular, statically non-negative signed integer expressions
+ * are ok for both.
  *
- * NOTE! Unsigned types smaller than 'int' are implicitly
- * converted to 'int' in expressions, and are accepted for
- * signed conversions for now. This is debatable.
+ * NOTE! Unsigned types smaller than 'int' are implicitly converted to 'int'
+ * in expressions, and are accepted for signed conversions for now.
+ * This is debatable.
  *
- * Note that 'x' is the original expression, and 'ux' is
- * the unique variable that contains the value.
+ * Note that 'x' is the original expression, and 'ux' is the unique variable
+ * that contains the value.
  *
- * We use 'ux' for pure type checking, and 'x' for when
- * we need to look at the value (but without evaluating
- * it for side effects! Careful to only ever evaluate it
- * with sizeof() or __builtin_constant_p() etc).
+ * We use 'ux' for pure type checking, and 'x' for when we need to look at the
+ * value (but without evaluating it for side effects!
+ * Careful to only ever evaluate it with sizeof() or __builtin_constant_p() etc).
  *
- * Pointers end up being checked by the normal C type
- * rules at the actual comparison, and these expressions
- * only need to be careful to not cause warnings for
- * pointer use.
+ * Pointers end up being checked by the normal C type rules at the actual
+ * comparison, and these expressions only need to be careful to not cause
+ * warnings for pointer use.
  */
 #define __signed_type_use(x, ux) (2 + __is_nonneg(x, ux))
 #define __unsigned_type_use(x, ux) (1 + 2 * (sizeof(ux) < 4))
@@ -57,19 +52,19 @@
 	__signed_type_use(x, ux) : __unsigned_type_use(x, ux))
 
 /*
- * To avoid warnings about casting pointers to integers
- * of different sizes, we need that special sign type.
+ * Check whether a signed value is always non-negative.
  *
- * On 64-bit we can just always use 'long', since any
- * integer or pointer type can just be cast to that.
+ * A cast is needed to avoid any warnings from values that aren't signed
+ * integer types (in which case the result doesn't matter).
  *
- * This does not work for 128-bit signed integers since
- * the cast would truncate them, but we do not use s128
- * types in the kernel (we do use 'u128', but they will
- * be handled by the !is_signed_type() case).
+ * On 64-bit any integer or pointer type can safely be cast to 'long'.
+ * But on 32-bit we need to avoid warnings about casting pointers to integers
+ * of different sizes without truncating 64-bit values so 'long' or 'long long'
+ * must be used depending on the size of the value.
  *
- * NOTE! The cast is there only to avoid any warnings
- * from when values that aren't signed integer types.
+ * This does not work for 128-bit signed integers since the cast would truncate
+ * them, but we do not use s128 types in the kernel (we do use 'u128',
+ * but they are handled by the !is_signed_type() case).
  */
 #ifdef CONFIG_64BIT
   #define __signed_type(ux) long
-- 
2.47.3

[PATCH v2 08/12 6.6.y] minmax.h: reduce the #define expansion of min(), max() and clamp()

[Eliav Farber]

From: David Laight <David.Laight@ACULAB.COM>

[ Upstream commit b280bb27a9f7c91ddab730e1ad91a9c18a051f41 ]

Since the test for signed values being non-negative only relies on
__builtion_constant_p() (not is_constexpr()) it can use the 'ux' variable
instead of the caller supplied expression.  This means that the #define
parameters are only expanded twice.  Once in the code and once quoted in
the error message.

Link: https://lkml.kernel.org/r/051afc171806425da991908ed8688a98@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 include/linux/minmax.h | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 24e4b372649a..6f7ea669d305 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -46,10 +46,10 @@
  * comparison, and these expressions only need to be careful to not cause
  * warnings for pointer use.
  */
-#define __signed_type_use(x, ux) (2 + __is_nonneg(x, ux))
-#define __unsigned_type_use(x, ux) (1 + 2 * (sizeof(ux) < 4))
-#define __sign_use(x, ux) (is_signed_type(typeof(ux)) ? \
-	__signed_type_use(x, ux) : __unsigned_type_use(x, ux))
+#define __signed_type_use(ux) (2 + __is_nonneg(ux))
+#define __unsigned_type_use(ux) (1 + 2 * (sizeof(ux) < 4))
+#define __sign_use(ux) (is_signed_type(typeof(ux)) ? \
+	__signed_type_use(ux) : __unsigned_type_use(ux))
 
 /*
  * Check whether a signed value is always non-negative.
@@ -71,13 +71,13 @@
 #else
   #define __signed_type(ux) typeof(__builtin_choose_expr(sizeof(ux) > 4, 1LL, 1L))
 #endif
-#define __is_nonneg(x, ux) statically_true((__signed_type(ux))(x) >= 0)
+#define __is_nonneg(ux) statically_true((__signed_type(ux))(ux) >= 0)
 
-#define __types_ok(x, y, ux, uy) \
-	(__sign_use(x, ux) & __sign_use(y, uy))
+#define __types_ok(ux, uy) \
+	(__sign_use(ux) & __sign_use(uy))
 
-#define __types_ok3(x, y, z, ux, uy, uz) \
-	(__sign_use(x, ux) & __sign_use(y, uy) & __sign_use(z, uz))
+#define __types_ok3(ux, uy, uz) \
+	(__sign_use(ux) & __sign_use(uy) & __sign_use(uz))
 
 #define __cmp_op_min <
 #define __cmp_op_max >
@@ -92,7 +92,7 @@
 
 #define __careful_cmp_once(op, x, y, ux, uy) ({		\
 	__auto_type ux = (x); __auto_type uy = (y);	\
-	BUILD_BUG_ON_MSG(!__types_ok(x, y, ux, uy),	\
+	BUILD_BUG_ON_MSG(!__types_ok(ux, uy),		\
 		#op"("#x", "#y") signedness error");	\
 	__cmp(op, ux, uy); })
 
@@ -109,7 +109,7 @@
 	static_assert(__builtin_choose_expr(__is_constexpr((lo) > (hi)), 	\
 			(lo) <= (hi), true),					\
 		"clamp() low limit " #lo " greater than high limit " #hi);	\
-	BUILD_BUG_ON_MSG(!__types_ok3(val, lo, hi, uval, ulo, uhi),		\
+	BUILD_BUG_ON_MSG(!__types_ok3(uval, ulo, uhi),				\
 		"clamp("#val", "#lo", "#hi") signedness error");		\
 	__clamp(uval, ulo, uhi); })
 
@@ -149,7 +149,7 @@
 
 #define __careful_op3(op, x, y, z, ux, uy, uz) ({			\
 	__auto_type ux = (x); __auto_type uy = (y);__auto_type uz = (z);\
-	BUILD_BUG_ON_MSG(!__types_ok3(x, y, z, ux, uy, uz),		\
+	BUILD_BUG_ON_MSG(!__types_ok3(ux, uy, uz),			\
 		#op"3("#x", "#y", "#z") signedness error");		\
 	__cmp(op, ux, __cmp(op, uy, uz)); })
 
-- 
2.47.3

[PATCH v2 09/12 6.6.y] minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp()

[Eliav Farber]

From: David Laight <David.Laight@ACULAB.COM>

[ Upstream commit a5743f32baec4728711bbc01d6ac2b33d4c67040 ]

Use BUILD_BUG_ON_MSG(statically_true(ulo > uhi), ...) for the sanity check
of the bounds in clamp().  Gives better error coverage and one less
expansion of the arguments.

Link: https://lkml.kernel.org/r/34d53778977747f19cce2abb287bb3e6@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 include/linux/minmax.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 6f7ea669d305..91aa1b90c1bb 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -106,8 +106,7 @@
 	__auto_type uval = (val);						\
 	__auto_type ulo = (lo);							\
 	__auto_type uhi = (hi);							\
-	static_assert(__builtin_choose_expr(__is_constexpr((lo) > (hi)), 	\
-			(lo) <= (hi), true),					\
+	BUILD_BUG_ON_MSG(statically_true(ulo > uhi),				\
 		"clamp() low limit " #lo " greater than high limit " #hi);	\
 	BUILD_BUG_ON_MSG(!__types_ok3(uval, ulo, uhi),				\
 		"clamp("#val", "#lo", "#hi") signedness error");		\
-- 
2.47.3

[PATCH v2 10/12 6.6.y] minmax.h: move all the clamp() definitions after the min/max() ones

[Eliav Farber]

From: David Laight <David.Laight@ACULAB.COM>

[ Upstream commit c3939872ee4a6b8bdcd0e813c66823b31e6e26f7 ]

At some point the definitions for clamp() got added in the middle of the
ones for min() and max().  Re-order the definitions so they are more
sensibly grouped.

Link: https://lkml.kernel.org/r/8bb285818e4846469121c8abc3dfb6e2@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 include/linux/minmax.h | 109 +++++++++++++++++++----------------------
 1 file changed, 51 insertions(+), 58 deletions(-)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 91aa1b90c1bb..75fb7a6ad4c6 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -99,22 +99,6 @@
 #define __careful_cmp(op, x, y) \
 	__careful_cmp_once(op, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
 
-#define __clamp(val, lo, hi)	\
-	((val) >= (hi) ? (hi) : ((val) <= (lo) ? (lo) : (val)))
-
-#define __clamp_once(val, lo, hi, uval, ulo, uhi) ({				\
-	__auto_type uval = (val);						\
-	__auto_type ulo = (lo);							\
-	__auto_type uhi = (hi);							\
-	BUILD_BUG_ON_MSG(statically_true(ulo > uhi),				\
-		"clamp() low limit " #lo " greater than high limit " #hi);	\
-	BUILD_BUG_ON_MSG(!__types_ok3(uval, ulo, uhi),				\
-		"clamp("#val", "#lo", "#hi") signedness error");		\
-	__clamp(uval, ulo, uhi); })
-
-#define __careful_clamp(val, lo, hi) \
-	__clamp_once(val, lo, hi, __UNIQUE_ID(v_), __UNIQUE_ID(l_), __UNIQUE_ID(h_))
-
 /**
  * min - return minimum of two values of the same or compatible types
  * @x: first value
@@ -170,6 +154,22 @@
 #define max3(x, y, z) \
 	__careful_op3(max, x, y, z, __UNIQUE_ID(x_), __UNIQUE_ID(y_), __UNIQUE_ID(z_))
 
+/**
+ * min_t - return minimum of two values, using the specified type
+ * @type: data type to use
+ * @x: first value
+ * @y: second value
+ */
+#define min_t(type, x, y) __cmp_once(min, type, x, y)
+
+/**
+ * max_t - return maximum of two values, using the specified type
+ * @type: data type to use
+ * @x: first value
+ * @y: second value
+ */
+#define max_t(type, x, y) __cmp_once(max, type, x, y)
+
 /**
  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
  * @x: value1
@@ -180,6 +180,22 @@
 	typeof(y) __y = (y);			\
 	__x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
 
+#define __clamp(val, lo, hi)	\
+	((val) >= (hi) ? (hi) : ((val) <= (lo) ? (lo) : (val)))
+
+#define __clamp_once(val, lo, hi, uval, ulo, uhi) ({				\
+	__auto_type uval = (val);						\
+	__auto_type ulo = (lo);							\
+	__auto_type uhi = (hi);							\
+	BUILD_BUG_ON_MSG(statically_true(ulo > uhi),				\
+		"clamp() low limit " #lo " greater than high limit " #hi);	\
+	BUILD_BUG_ON_MSG(!__types_ok3(uval, ulo, uhi),				\
+		"clamp("#val", "#lo", "#hi") signedness error");		\
+	__clamp(uval, ulo, uhi); })
+
+#define __careful_clamp(val, lo, hi) \
+	__clamp_once(val, lo, hi, __UNIQUE_ID(v_), __UNIQUE_ID(l_), __UNIQUE_ID(h_))
+
 /**
  * clamp - return a value clamped to a given range with strict typechecking
  * @val: current value
@@ -191,28 +207,30 @@
  */
 #define clamp(val, lo, hi) __careful_clamp(val, lo, hi)
 
-/*
- * ..and if you can't take the strict
- * types, you can specify one yourself.
- *
- * Or not use min/max/clamp at all, of course.
- */
-
 /**
- * min_t - return minimum of two values, using the specified type
- * @type: data type to use
- * @x: first value
- * @y: second value
+ * clamp_t - return a value clamped to a given range using a given type
+ * @type: the type of variable to use
+ * @val: current value
+ * @lo: minimum allowable value
+ * @hi: maximum allowable value
+ *
+ * This macro does no typechecking and uses temporary variables of type
+ * @type to make all the comparisons.
  */
-#define min_t(type, x, y) __cmp_once(min, type, x, y)
+#define clamp_t(type, val, lo, hi) __careful_clamp((type)(val), (type)(lo), (type)(hi))
 
 /**
- * max_t - return maximum of two values, using the specified type
- * @type: data type to use
- * @x: first value
- * @y: second value
+ * clamp_val - return a value clamped to a given range using val's type
+ * @val: current value
+ * @lo: minimum allowable value
+ * @hi: maximum allowable value
+ *
+ * This macro does no typechecking and uses temporary variables of whatever
+ * type the input argument @val is.  This is useful when @val is an unsigned
+ * type and @lo and @hi are literals that will otherwise be assigned a signed
+ * integer type.
  */
-#define max_t(type, x, y) __cmp_once(max, type, x, y)
+#define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
 
 /*
  * Do not check the array parameter using __must_be_array().
@@ -257,31 +275,6 @@
  */
 #define max_array(array, len) __minmax_array(max, array, len)
 
-/**
- * clamp_t - return a value clamped to a given range using a given type
- * @type: the type of variable to use
- * @val: current value
- * @lo: minimum allowable value
- * @hi: maximum allowable value
- *
- * This macro does no typechecking and uses temporary variables of type
- * @type to make all the comparisons.
- */
-#define clamp_t(type, val, lo, hi) __careful_clamp((type)(val), (type)(lo), (type)(hi))
-
-/**
- * clamp_val - return a value clamped to a given range using val's type
- * @val: current value
- * @lo: minimum allowable value
- * @hi: maximum allowable value
- *
- * This macro does no typechecking and uses temporary variables of whatever
- * type the input argument @val is.  This is useful when @val is an unsigned
- * type and @lo and @hi are literals that will otherwise be assigned a signed
- * integer type.
- */
-#define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
-
 static inline bool in_range64(u64 val, u64 start, u64 len)
 {
 	return (val - start) < len;
-- 
2.47.3

[PATCH v2 11/12 6.6.y] minmax.h: simplify the variants of clamp()

[Eliav Farber]

From: David Laight <David.Laight@ACULAB.COM>

[ Upstream commit 495bba17cdf95e9703af1b8ef773c55ef0dfe703 ]

Always pass a 'type' through to __clamp_once(), pass '__auto_type' from
clamp() itself.

The expansion of __types_ok3() is reasonable so it isn't worth the added
complexity of avoiding it when a fixed type is used for all three values.

Link: https://lkml.kernel.org/r/8f69f4deac014f558bab186444bac2e8@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 include/linux/minmax.h | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 75fb7a6ad4c6..2bbdd5b5e07e 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -183,29 +183,29 @@
 #define __clamp(val, lo, hi)	\
 	((val) >= (hi) ? (hi) : ((val) <= (lo) ? (lo) : (val)))
 
-#define __clamp_once(val, lo, hi, uval, ulo, uhi) ({				\
-	__auto_type uval = (val);						\
-	__auto_type ulo = (lo);							\
-	__auto_type uhi = (hi);							\
+#define __clamp_once(type, val, lo, hi, uval, ulo, uhi) ({			\
+	type uval = (val);							\
+	type ulo = (lo);							\
+	type uhi = (hi);							\
 	BUILD_BUG_ON_MSG(statically_true(ulo > uhi),				\
 		"clamp() low limit " #lo " greater than high limit " #hi);	\
 	BUILD_BUG_ON_MSG(!__types_ok3(uval, ulo, uhi),				\
 		"clamp("#val", "#lo", "#hi") signedness error");		\
 	__clamp(uval, ulo, uhi); })
 
-#define __careful_clamp(val, lo, hi) \
-	__clamp_once(val, lo, hi, __UNIQUE_ID(v_), __UNIQUE_ID(l_), __UNIQUE_ID(h_))
+#define __careful_clamp(type, val, lo, hi) \
+	__clamp_once(type, val, lo, hi, __UNIQUE_ID(v_), __UNIQUE_ID(l_), __UNIQUE_ID(h_))
 
 /**
- * clamp - return a value clamped to a given range with strict typechecking
+ * clamp - return a value clamped to a given range with typechecking
  * @val: current value
  * @lo: lowest allowable value
  * @hi: highest allowable value
  *
- * This macro does strict typechecking of @lo/@hi to make sure they are of the
- * same type as @val.  See the unnecessary pointer comparisons.
+ * This macro checks @val/@lo/@hi to make sure they have compatible
+ * signedness.
  */
-#define clamp(val, lo, hi) __careful_clamp(val, lo, hi)
+#define clamp(val, lo, hi) __careful_clamp(__auto_type, val, lo, hi)
 
 /**
  * clamp_t - return a value clamped to a given range using a given type
@@ -217,7 +217,7 @@
  * This macro does no typechecking and uses temporary variables of type
  * @type to make all the comparisons.
  */
-#define clamp_t(type, val, lo, hi) __careful_clamp((type)(val), (type)(lo), (type)(hi))
+#define clamp_t(type, val, lo, hi) __careful_clamp(type, val, lo, hi)
 
 /**
  * clamp_val - return a value clamped to a given range using val's type
@@ -230,7 +230,7 @@
  * type and @lo and @hi are literals that will otherwise be assigned a signed
  * integer type.
  */
-#define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
+#define clamp_val(val, lo, hi) __careful_clamp(typeof(val), val, lo, hi)
 
 /*
  * Do not check the array parameter using __must_be_array().
-- 
2.47.3

[PATCH v2 12/12 6.6.y] minmax.h: remove some #defines that are only expanded once

[Eliav Farber]

From: David Laight <David.Laight@ACULAB.COM>

[ Upstream commit 2b97aaf74ed534fb838d09867d09a3ca5d795208 ]

The bodies of __signed_type_use() and __unsigned_type_use() are much the
same size as their names - so put the bodies in the only line that expands
them.

Similarly __signed_type() is defined separately for 64bit and then used
exactly once just below.

Change the test for __signed_type from CONFIG_64BIT to one based on gcc
defined macros so that the code is valid if it gets used outside of a
kernel build.

Link: https://lkml.kernel.org/r/9386d1ebb8974fbabbed2635160c3975@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 include/linux/minmax.h | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 2bbdd5b5e07e..eaaf5c008e4d 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -46,10 +46,8 @@
  * comparison, and these expressions only need to be careful to not cause
  * warnings for pointer use.
  */
-#define __signed_type_use(ux) (2 + __is_nonneg(ux))
-#define __unsigned_type_use(ux) (1 + 2 * (sizeof(ux) < 4))
 #define __sign_use(ux) (is_signed_type(typeof(ux)) ? \
-	__signed_type_use(ux) : __unsigned_type_use(ux))
+	(2 + __is_nonneg(ux)) : (1 + 2 * (sizeof(ux) < 4)))
 
 /*
  * Check whether a signed value is always non-negative.
@@ -57,7 +55,7 @@
  * A cast is needed to avoid any warnings from values that aren't signed
  * integer types (in which case the result doesn't matter).
  *
- * On 64-bit any integer or pointer type can safely be cast to 'long'.
+ * On 64-bit any integer or pointer type can safely be cast to 'long long'.
  * But on 32-bit we need to avoid warnings about casting pointers to integers
  * of different sizes without truncating 64-bit values so 'long' or 'long long'
  * must be used depending on the size of the value.
@@ -66,12 +64,12 @@
  * them, but we do not use s128 types in the kernel (we do use 'u128',
  * but they are handled by the !is_signed_type() case).
  */
-#ifdef CONFIG_64BIT
-  #define __signed_type(ux) long
+#if __SIZEOF_POINTER__ == __SIZEOF_LONG_LONG__
+#define __is_nonneg(ux) statically_true((long long)(ux) >= 0)
 #else
-  #define __signed_type(ux) typeof(__builtin_choose_expr(sizeof(ux) > 4, 1LL, 1L))
+#define __is_nonneg(ux) statically_true( \
+	(typeof(__builtin_choose_expr(sizeof(ux) > 4, 1LL, 1L)))(ux) >= 0)
 #endif
-#define __is_nonneg(ux) statically_true((__signed_type(ux))(ux) >= 0)
 
 #define __types_ok(ux, uy) \
 	(__sign_use(ux) & __sign_use(uy))
-- 
2.47.3

Re: [PATCH v2 00/12 6.6.y] Backport minmax.h updates from v6.17-rc7

[Greg KH]

On Mon, Sep 29, 2025 at 05:17:21PM +0000, Eliav Farber wrote:
> This series backports 15 patches to update minmax.h in the 6.6.y branch,
> aligning it with v6.17-rc7.
> 
> The ultimate goal is to synchronize all longterm branches so that they
> include the full set of minmax.h changes.
> 
> The key motivation is to bring in commit d03eba99f5bf ("minmax: allow
> min()/max()/clamp() if the arguments have the same signedness"), which
> is missing in older kernels.
> 
> In mainline, this change enables min()/max()/clamp() to accept mixed
> argument types, provided both have the same signedness. Without it,
> backported patches that use these forms may trigger compiler warnings,
> which escalate to build failures when -Werror is enabled.

All now queued up, thanks!

greg k-h