kernel/linux.git/include/linux/minmax.h, branch v6.19.11

include/linux: change "__auto_type" to "auto"

2025-12-08T23:32:14+00:00

Replace instances of "__auto_type" with "auto" in include/linux. Signed-off-by: H. Peter Anvin (Intel)

minmax.h: remove some #defines that are only expanded once

2025-01-25T06:47:27+00:00

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 Cc: Andy Shevchenko Cc: Arnd Bergmann Cc: Christoph Hellwig Cc: Dan Carpenter Cc: Jason A. Donenfeld Cc: Jens Axboe Cc: Lorenzo Stoakes Cc: Mateusz Guzik Cc: Matthew Wilcox Cc: Pedro Falcato Signed-off-by: Andrew Morton

minmax.h: simplify the variants of clamp()

2025-01-25T06:47:26+00:00

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 Cc: Andy Shevchenko Cc: Arnd Bergmann Cc: Christoph Hellwig Cc: Dan Carpenter Cc: Jason A. Donenfeld Cc: Jens Axboe Cc: Lorenzo Stoakes Cc: Mateusz Guzik Cc: Matthew Wilcox Cc: Pedro Falcato Signed-off-by: Andrew Morton

minmax.h: move all the clamp() definitions after the min/max() ones

2025-01-25T06:47:26+00:00

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 Cc: Andy Shevchenko Cc: Arnd Bergmann Cc: Christoph Hellwig Cc: Dan Carpenter Cc: Jason A. Donenfeld Cc: Jens Axboe Cc: Lorenzo Stoakes Cc: Mateusz Guzik Cc: Matthew Wilcox Cc: Pedro Falcato Signed-off-by: Andrew Morton

minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp()

2025-01-25T06:47:26+00:00

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 Cc: Andy Shevchenko Cc: Arnd Bergmann Cc: Christoph Hellwig Cc: Dan Carpenter Cc: Jason A. Donenfeld Cc: Jens Axboe Cc: Lorenzo Stoakes Cc: Mateusz Guzik Cc: Matthew Wilcox Cc: Pedro Falcato Signed-off-by: Andrew Morton

minmax.h: reduce the #define expansion of min(), max() and clamp()

2025-01-25T06:47:26+00:00

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 Cc: Andy Shevchenko Cc: Arnd Bergmann Cc: Christoph Hellwig Cc: Dan Carpenter Cc: Jason A. Donenfeld Cc: Jens Axboe Cc: Lorenzo Stoakes Cc: Mateusz Guzik Cc: Matthew Wilcox Cc: Pedro Falcato Signed-off-by: Andrew Morton

minmax.h: update some comments

2025-01-25T06:47:26+00:00

- 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 Cc: Andy Shevchenko Cc: Arnd Bergmann Cc: Christoph Hellwig Cc: Dan Carpenter Cc: Jason A. Donenfeld Cc: Jens Axboe Cc: Lorenzo Stoakes Cc: Mateusz Guzik Cc: Matthew Wilcox Cc: Pedro Falcato Signed-off-by: Andrew Morton

minmax.h: add whitespace around operators and after commas

2025-01-25T06:47:26+00:00

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 Cc: Andy Shevchenko Cc: Arnd Bergmann Cc: Christoph Hellwig Cc: Dan Carpenter Cc: Jason A. Donenfeld Cc: Jens Axboe Cc: Lorenzo Stoakes Cc: Mateusz Guzik Cc: Matthew Wilcox Cc: Pedro Falcato Signed-off-by: Andrew Morton

minmax: fix up min3() and max3() too

2024-07-31T16:57:18+00:00

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 Acked-by: Arnd Bergmann Signed-off-by: Linus Torvalds

minmax: improve macro expansion and type checking

2024-07-30T17:36:47+00:00

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 Cc: David Laight Cc: Lorenzo Stoakes Signed-off-by: Linus Torvalds