Merge tag 'erofs-for-5.8-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs (8be3a53e) · Commits · 戴 / test

Pull erofs fix from Gao Xiang: "Fix a regression which uses potential uninitialized high 32-bit value unexpectedly recently observed with specific compiler options" * tag 'erofs-for-5.8-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs: erofs: fix partially uninitialized misuse in z_erofs_onlinepage_fixup

fs/erofs/zdata.h

+10 −10

Original line number	Diff line number	Diff line
		@@ -144,22 +144,22 @@ static inline void z_erofs_onlinepage_init(struct page *page)
		static inline void z_erofs_onlinepage_fixup(struct page *page,
		uintptr_t index, bool down)
		{
		unsigned long *p, o, v, id;
		repeat:
		p = &page_private(page);
		o = READ_ONCE(*p);
		union z_erofs_onlinepage_converter u = { .v = &page_private(page) };
		int orig, orig_index, val;

		id = o >> Z_EROFS_ONLINEPAGE_INDEX_SHIFT;
		if (id) {
		repeat:
		orig = atomic_read(u.o);
		orig_index = orig >> Z_EROFS_ONLINEPAGE_INDEX_SHIFT;
		if (orig_index) {
		if (!index)
		return;

		DBG_BUGON(id != index);
		DBG_BUGON(orig_index != index);
		}

		v = (index << Z_EROFS_ONLINEPAGE_INDEX_SHIFT) \|
		((o & Z_EROFS_ONLINEPAGE_COUNT_MASK) + (unsigned int)down);
		if (cmpxchg(p, o, v) != o)
		val = (index << Z_EROFS_ONLINEPAGE_INDEX_SHIFT) \|
		((orig & Z_EROFS_ONLINEPAGE_COUNT_MASK) + (unsigned int)down);
		if (atomic_cmpxchg(u.o, orig, val) != orig)
		goto repeat;
		}

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