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 <seanjc@xxxxxxxxxx>
---
tools/include/asm-generic/bitops/atomic.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
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 <asm/types.h>
#include <asm/bitsperlong.h>
-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));
}
--
2.38.1.584.g0f3c55d4c2-goog
