From 7f2b47f22b825c16d9843e6e78bbb2370d2c31a0 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Sat, 19 Nov 2022 01:34:45 +0000 Subject: tools: Take @bit as an "unsigned long" in {clear,set}_bit() helpers Take @bit as an unsigned long instead of a signed int in clear_bit() and set_bit() so that they match the double-underscore versions, __clear_bit() and __set_bit(). This will allow converting users that really don't want atomic operations to the double-underscores without introducing a functional change, which will in turn allow making {clear,set}_bit() atomic (as advertised). Practically speaking, this _should_ have no functional impact. KVM's selftests usage is either hardcoded (Hyper-V tests) or is artificially limited (arch_timer test and dirty_log test). In KVM, dirty_log test is the only mildly interesting case as it's use indirectly restricted to unsigned 32-bit values, but in theory it could generate a negative value when cast to a signed int. But in that case, taking an "unsigned long" is actually a bug fix. Perf's usage is more difficult to audit, but any code that is affected by the switch is likely already broken. perf_header__{set,clear}_feat() and perf_file_header__read() effectively use only hardcoded enums with small, positive values, atom_new() passes an unsigned long, but its value is capped at 128 via NR_ATOM_PER_PAGE, etc... The only real potential for breakage is in the perf flows that take a "cpu", but it's unlikely perf is subtly relying on a negative index into bitmaps, e.g. "cpu" can be "-1", but only as "not valid" placeholder. Note, tools/testing/nvdimm/ makes heavy use of set_bit(), but that code builds into a kernel module of sorts, i.e. pulls in all of the kernel's header and so is getting the kernel's atomic set_bit(). The NVDIMM test usage of atomics is likely unnecessary, e.g. ndtest_dimm_register() sets bits in a local variable, but that's neither here nor there as far as this change is concerned. Signed-off-by: Sean Christopherson Message-Id: <20221119013450.2643007-5-seanjc@google.com> Signed-off-by: Paolo Bonzini --- tools/include/asm-generic/bitops/atomic.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'tools/include') diff --git a/tools/include/asm-generic/bitops/atomic.h b/tools/include/asm-generic/bitops/atomic.h index 2f6ea28764a7..f64b049d236c 100644 --- a/tools/include/asm-generic/bitops/atomic.h +++ b/tools/include/asm-generic/bitops/atomic.h @@ -5,12 +5,12 @@ #include #include -static inline void set_bit(int nr, unsigned long *addr) +static inline void set_bit(unsigned long nr, unsigned long *addr) { addr[nr / __BITS_PER_LONG] |= 1UL << (nr % __BITS_PER_LONG); } -static inline void clear_bit(int nr, unsigned long *addr) +static inline void clear_bit(unsigned long nr, unsigned long *addr) { addr[nr / __BITS_PER_LONG] &= ~(1UL << (nr % __BITS_PER_LONG)); } -- cgit v1.2.3