From 6a8b55ed4056ea5559ebe4f6a4b247f627870d4c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 26 Apr 2020 13:51:02 -0700 Subject: Linux 5.7-rc3 --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Makefile') diff --git a/Makefile b/Makefile index 49b2709ff44e..679f302a8b8b 100644 --- a/Makefile +++ b/Makefile @@ -2,7 +2,7 @@ VERSION = 5 PATCHLEVEL = 7 SUBLEVEL = 0 -EXTRAVERSION = -rc2 +EXTRAVERSION = -rc3 NAME = Kleptomaniac Octopus # *DOCUMENTATION* -- cgit v1.2.3 From 0e698dfa282211e414076f9dc7e83c1c288314fd Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 3 May 2020 14:56:04 -0700 Subject: Linux 5.7-rc4 --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Makefile') diff --git a/Makefile b/Makefile index 679f302a8b8b..3512f7b243dc 100644 --- a/Makefile +++ b/Makefile @@ -2,7 +2,7 @@ VERSION = 5 PATCHLEVEL = 7 SUBLEVEL = 0 -EXTRAVERSION = -rc3 +EXTRAVERSION = -rc4 NAME = Kleptomaniac Octopus # *DOCUMENTATION* -- cgit v1.2.3 From 78a5255ffb6a1af189a83e493d916ba1c54d8c75 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 9 May 2020 13:57:10 -0700 Subject: Stop the ad-hoc games with -Wno-maybe-initialized We have some rather random rules about when we accept the "maybe-initialized" warnings, and when we don't. For example, we consider it unreliable for gcc versions < 4.9, but also if -O3 is enabled, or if optimizing for size. And then various kernel config options disabled it, because they know that they trigger that warning by confusing gcc sufficiently (ie PROFILE_ALL_BRANCHES). And now gcc-10 seems to be introducing a lot of those warnings too, so it falls under the same heading as 4.9 did. At the same time, we have a very straightforward way to _enable_ that warning when wanted: use "W=2" to enable more warnings. So stop playing these ad-hoc games, and just disable that warning by default, with the known and straight-forward "if you want to work on the extra compiler warnings, use W=123". Would it be great to have code that is always so obvious that it never confuses the compiler whether a variable is used initialized or not? Yes, it would. In a perfect world, the compilers would be smarter, and our source code would be simpler. That's currently not the world we live in, though. Signed-off-by: Linus Torvalds --- Makefile | 7 +++---- init/Kconfig | 18 ------------------ kernel/trace/Kconfig | 1 - 3 files changed, 3 insertions(+), 23 deletions(-) (limited to 'Makefile') diff --git a/Makefile b/Makefile index 3512f7b243dc..1e94f4f15d92 100644 --- a/Makefile +++ b/Makefile @@ -729,10 +729,6 @@ else ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE KBUILD_CFLAGS += -Os endif -ifdef CONFIG_CC_DISABLE_WARN_MAYBE_UNINITIALIZED -KBUILD_CFLAGS += -Wno-maybe-uninitialized -endif - # Tell gcc to never replace conditional load with a non-conditional one KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0) KBUILD_CFLAGS += $(call cc-option,-fno-allow-store-data-races) @@ -881,6 +877,9 @@ KBUILD_CFLAGS += -Wno-pointer-sign # disable stringop warnings in gcc 8+ KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation) +# Enabled with W=2, disabled by default as noisy +KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized) + # disable invalid "can't wrap" optimizations for signed / pointers KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow) diff --git a/init/Kconfig b/init/Kconfig index 9e22ee8fbd75..9278a603d399 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -39,22 +39,6 @@ config TOOLS_SUPPORT_RELR config CC_HAS_ASM_INLINE def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) -config CC_HAS_WARN_MAYBE_UNINITIALIZED - def_bool $(cc-option,-Wmaybe-uninitialized) - help - GCC >= 4.7 supports this option. - -config CC_DISABLE_WARN_MAYBE_UNINITIALIZED - bool - depends on CC_HAS_WARN_MAYBE_UNINITIALIZED - default CC_IS_GCC && GCC_VERSION < 40900 # unreliable for GCC < 4.9 - help - GCC's -Wmaybe-uninitialized is not reliable by definition. - Lots of false positive warnings are produced in some cases. - - If this option is enabled, -Wno-maybe-uninitialzed is passed - to the compiler to suppress maybe-uninitialized warnings. - config CONSTRUCTORS bool depends on !UML @@ -1257,14 +1241,12 @@ config CC_OPTIMIZE_FOR_PERFORMANCE config CC_OPTIMIZE_FOR_PERFORMANCE_O3 bool "Optimize more for performance (-O3)" depends on ARC - imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives help Choosing this option will pass "-O3" to your compiler to optimize the kernel yet more for performance. config CC_OPTIMIZE_FOR_SIZE bool "Optimize for size (-Os)" - imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives help Choosing this option will pass "-Os" to your compiler resulting in a smaller kernel. diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 402eef84c859..743647005f64 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -466,7 +466,6 @@ config PROFILE_ANNOTATED_BRANCHES config PROFILE_ALL_BRANCHES bool "Profile all if conditionals" if !FORTIFY_SOURCE select TRACE_BRANCH_PROFILING - imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives help This tracer profiles all branch conditions. Every if () taken in the kernel is recorded whether it hit or miss. -- cgit v1.2.3 From 5c45de21a2223fe46cf9488c99a7fbcf01527670 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 9 May 2020 14:30:29 -0700 Subject: gcc-10: disable 'zero-length-bounds' warning for now This is a fine warning, but we still have a number of zero-length arrays in the kernel that come from the traditional gcc extension. Yes, they are getting converted to flexible arrays, but in the meantime the gcc-10 warning about zero-length bounds is very verbose, and is hiding other issues. I missed one actual build failure because it was hidden among hundreds of lines of warning. Thankfully I caught it on the second go before pushing things out, but it convinced me that I really need to disable the new warnings for now. We'll hopefully be all done with our conversion to flexible arrays in the not too distant future, and we can then re-enable this warning. Signed-off-by: Linus Torvalds --- Makefile | 3 +++ 1 file changed, 3 insertions(+) (limited to 'Makefile') diff --git a/Makefile b/Makefile index 1e94f4f15d92..68a781326dd7 100644 --- a/Makefile +++ b/Makefile @@ -877,6 +877,9 @@ KBUILD_CFLAGS += -Wno-pointer-sign # disable stringop warnings in gcc 8+ KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation) +# We'll want to enable this eventually, but it's not going away for 5.7 at least +KBUILD_CFLAGS += $(call cc-disable-warning, zero-length-bounds) + # Enabled with W=2, disabled by default as noisy KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized) -- cgit v1.2.3 From 44720996e2d79e47d508b0abe99b931a726a3197 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 9 May 2020 14:52:44 -0700 Subject: gcc-10: disable 'array-bounds' warning for now This is another fine warning, related to the 'zero-length-bounds' one, but hitting the same historical code in the kernel. Because C didn't historically support flexible array members, we have code that instead uses a one-sized array, the same way we have cases of zero-sized arrays. The one-sized arrays come from either not wanting to use the gcc zero-sized array extension, or from a slight convenience-feature, where particularly for strings, the size of the structure now includes the allocation for the final NUL character. So with a "char name[1];" at the end of a structure, you can do things like v = my_malloc(sizeof(struct vendor) + strlen(name)); and avoid the "+1" for the terminator. Yes, the modern way to do that is with a flexible array, and using 'offsetof()' instead of 'sizeof()', and adding the "+1" by hand. That also technically gets the size "more correct" in that it avoids any alignment (and thus padding) issues, but this is another long-term cleanup thing that will not happen for 5.7. So disable the warning for now, even though it's potentially quite useful. Having a slew of warnings that then hide more urgent new issues is not an improvement. Signed-off-by: Linus Torvalds --- Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'Makefile') diff --git a/Makefile b/Makefile index 68a781326dd7..b4c88f0eb6fe 100644 --- a/Makefile +++ b/Makefile @@ -879,6 +879,7 @@ KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation) # We'll want to enable this eventually, but it's not going away for 5.7 at least KBUILD_CFLAGS += $(call cc-disable-warning, zero-length-bounds) +KBUILD_CFLAGS += $(call cc-disable-warning, array-bounds) # Enabled with W=2, disabled by default as noisy KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized) -- cgit v1.2.3 From 5a76021c2eff7fcf2f0918a08fd8a37ce7922921 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 9 May 2020 15:40:52 -0700 Subject: gcc-10: disable 'stringop-overflow' warning for now This is the final array bounds warning removal for gcc-10 for now. Again, the warning is good, and we should re-enable all these warnings when we have converted all the legacy array declaration cases to flexible arrays. But in the meantime, it's just noise. Signed-off-by: Linus Torvalds --- Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'Makefile') diff --git a/Makefile b/Makefile index b4c88f0eb6fe..abdb355d3f46 100644 --- a/Makefile +++ b/Makefile @@ -880,6 +880,7 @@ KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation) # We'll want to enable this eventually, but it's not going away for 5.7 at least KBUILD_CFLAGS += $(call cc-disable-warning, zero-length-bounds) KBUILD_CFLAGS += $(call cc-disable-warning, array-bounds) +KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow) # Enabled with W=2, disabled by default as noisy KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized) -- cgit v1.2.3 From adc71920969870dfa54e8f40dac8616284832d02 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 9 May 2020 15:45:21 -0700 Subject: gcc-10: disable 'restrict' warning for now gcc-10 now warns about passing aliasing pointers to functions that take restricted pointers. That's actually a great warning, and if we ever start using 'restrict' in the kernel, it might be quite useful. But right now we don't, and it turns out that the only thing this warns about is an idiom where we have declared a few functions to be "printf-like" (which seems to make gcc pick up the restricted pointer thing), and then we print to the same buffer that we also use as an input. And people do that as an odd concatenation pattern, with code like this: #define sysfs_show_gen_prop(buffer, fmt, ...) \ snprintf(buffer, PAGE_SIZE, "%s"fmt, buffer, __VA_ARGS__) where we have 'buffer' as both the destination of the final result, and as the initial argument. Yes, it's a bit questionable. And outside of the kernel, people do have standard declarations like int snprintf( char *restrict buffer, size_t bufsz, const char *restrict format, ... ); where that output buffer is marked as a restrict pointer that cannot alias with any other arguments. But in the context of the kernel, that 'use snprintf() to concatenate to the end result' does work, and the pattern shows up in multiple places. And we have not marked our own version of snprintf() as taking restrict pointers, so the warning is incorrect for now, and gcc picks it up on its own. If we do start using 'restrict' in the kernel (and it might be a good idea if people find places where it matters), we'll need to figure out how to avoid this issue for snprintf and friends. But in the meantime, this warning is not useful. Signed-off-by: Linus Torvalds --- Makefile | 3 +++ 1 file changed, 3 insertions(+) (limited to 'Makefile') diff --git a/Makefile b/Makefile index abdb355d3f46..a45d8d09f354 100644 --- a/Makefile +++ b/Makefile @@ -882,6 +882,9 @@ KBUILD_CFLAGS += $(call cc-disable-warning, zero-length-bounds) KBUILD_CFLAGS += $(call cc-disable-warning, array-bounds) KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow) +# Another good warning that we'll want to enable eventually +KBUILD_CFLAGS += $(call cc-disable-warning, restrict) + # Enabled with W=2, disabled by default as noisy KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized) -- cgit v1.2.3 From 2ef96a5bb12be62ef75b5828c0aab838ebb29cb8 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 10 May 2020 15:16:58 -0700 Subject: Linux 5.7-rc5 --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Makefile') diff --git a/Makefile b/Makefile index a45d8d09f354..11fe9b1535de 100644 --- a/Makefile +++ b/Makefile @@ -2,7 +2,7 @@ VERSION = 5 PATCHLEVEL = 7 SUBLEVEL = 0 -EXTRAVERSION = -rc4 +EXTRAVERSION = -rc5 NAME = Kleptomaniac Octopus # *DOCUMENTATION* -- cgit v1.2.3 From b9bbe6ed63b2b9f2c9ee5cbd0f2c946a2723f4ce Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 17 May 2020 16:48:37 -0700 Subject: Linux 5.7-rc6 --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Makefile') diff --git a/Makefile b/Makefile index 11fe9b1535de..04f5662ae61a 100644 --- a/Makefile +++ b/Makefile @@ -2,7 +2,7 @@ VERSION = 5 PATCHLEVEL = 7 SUBLEVEL = 0 -EXTRAVERSION = -rc5 +EXTRAVERSION = -rc6 NAME = Kleptomaniac Octopus # *DOCUMENTATION* -- cgit v1.2.3