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Patch series "tools: testing: Use existing atomic.h for vma/maple tests", v2. De-duplicating this lets us delete a bit of code. Ulterior motive: I'm working on a new set of the userspace-based unit tests, which will need the atomics API too. That would involve even more duplication, so while the win in this patchset alone is very minimal, it looks a lot more significant with my other WIP patchset. I've tested these commands: make -C tools/testing/vma -j tools/testing/vma/vma make -C tools/testing/radix-tree -j tools/testing/radix-tree/maple Note the EXTRA_CFLAGS patch is actually orthogonal, let me know if you'd prefer I send it separately. This patch (of 4): The VMA tests need an operation equivalent to atomic_inc_unless_negative() to implement a fake mapping_map_writable(). Adding it will enable them to switch to the shared atomic headers and simplify that fake implementation. In order to add that, also add atomic_try_cmpxchg() which can be used to implement it. This is copied from Documentation/atomic_t.txt. Then, implement atomic_inc_unless_negative() itself based on the raw_atomic_dec_unless_positive() in include/linux/atomic/atomic-arch-fallback.h. There's no present need for a highly-optimised version of this (nor any reason to think this implementation is sub-optimal on x86) so just implement this with generic C, no x86-specifics. Link: https://lkml.kernel.org/r/20250828-b4-vma-no-atomic-h-v2-0-02d146a58ed2@google.com Link: https://lkml.kernel.org/r/20250828-b4-vma-no-atomic-h-v2-1-02d146a58ed2@google.com Signed-off-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Pedro Falcato <pfalcato@suse.de> Cc: Jann Horn <jannh@google.com> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
38 lines
801 B
C
38 lines
801 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __TOOLS_LINUX_ATOMIC_H
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#define __TOOLS_LINUX_ATOMIC_H
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#include <asm/atomic.h>
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void atomic_long_set(atomic_long_t *v, long i);
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/* atomic_cmpxchg_relaxed */
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#ifndef atomic_cmpxchg_relaxed
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#define atomic_cmpxchg_relaxed atomic_cmpxchg
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#define atomic_cmpxchg_release atomic_cmpxchg
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#endif /* atomic_cmpxchg_relaxed */
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static inline bool atomic_try_cmpxchg(atomic_t *ptr, int *oldp, int new)
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{
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int ret, old = *oldp;
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ret = atomic_cmpxchg(ptr, old, new);
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if (ret != old)
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*oldp = ret;
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return ret == old;
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}
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static inline bool atomic_inc_unless_negative(atomic_t *v)
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{
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int c = atomic_read(v);
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do {
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if (unlikely(c < 0))
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return false;
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} while (!atomic_try_cmpxchg(v, &c, c + 1));
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return true;
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}
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#endif /* __TOOLS_LINUX_ATOMIC_H */
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