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

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 f6ea15821cea..a6a7be83fae6 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)

+/* + * 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) \

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 */

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)); })

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;

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))