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author | David S. Miller <davem@davemloft.net> | 2012-06-29 00:37:00 (GMT) |
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committer | David S. Miller <davem@davemloft.net> | 2012-06-29 00:37:00 (GMT) |
commit | b26d344c6b87058ae3e8f919a18580abfc4204eb (patch) | |
tree | ff7026df8e8715e3c63d0ff4ff697a9fac6323fb /arch/x86/include/asm/pgtable-3level.h | |
parent | 82aee5d7c01fd1a398e938e496e6cb8841775f91 (diff) | |
parent | 76fbc247b9aebc30f6d2c8ec1f69edcb68eaa328 (diff) | |
download | linux-b26d344c6b87058ae3e8f919a18580abfc4204eb.tar.xz |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Conflicts:
drivers/net/caif/caif_hsi.c
drivers/net/usb/qmi_wwan.c
The qmi_wwan merge was trivial.
The caif_hsi.c, on the other hand, was not. It's a conflict between
1c385f1fdf6f9c66d982802cd74349c040980b50 ("caif-hsi: Replace platform
device with ops structure.") in the net-next tree and commit
39abbaef19cd0a30be93794aa4773c779c3eb1f3 ("caif-hsi: Postpone init of
HIS until open()") in the net tree.
I did my best with that one and will ask Sjur to check it out.
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/x86/include/asm/pgtable-3level.h')
-rw-r--r-- | arch/x86/include/asm/pgtable-3level.h | 30 |
1 files changed, 17 insertions, 13 deletions
diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h index 43876f1..cb00ccc 100644 --- a/arch/x86/include/asm/pgtable-3level.h +++ b/arch/x86/include/asm/pgtable-3level.h @@ -47,16 +47,26 @@ static inline void native_set_pte(pte_t *ptep, pte_t pte) * they can run pmd_offset_map_lock or pmd_trans_huge or other pmd * operations. * - * Without THP if the mmap_sem is hold for reading, the - * pmd can only transition from null to not null while pmd_read_atomic runs. - * So there's no need of literally reading it atomically. + * Without THP if the mmap_sem is hold for reading, the pmd can only + * transition from null to not null while pmd_read_atomic runs. So + * we can always return atomic pmd values with this function. * * With THP if the mmap_sem is hold for reading, the pmd can become - * THP or null or point to a pte (and in turn become "stable") at any - * time under pmd_read_atomic, so it's mandatory to read it atomically - * with cmpxchg8b. + * trans_huge or none or point to a pte (and in turn become "stable") + * at any time under pmd_read_atomic. We could read it really + * atomically here with a atomic64_read for the THP enabled case (and + * it would be a whole lot simpler), but to avoid using cmpxchg8b we + * only return an atomic pmdval if the low part of the pmdval is later + * found stable (i.e. pointing to a pte). And we're returning a none + * pmdval if the low part of the pmd is none. In some cases the high + * and low part of the pmdval returned may not be consistent if THP is + * enabled (the low part may point to previously mapped hugepage, + * while the high part may point to a more recently mapped hugepage), + * but pmd_none_or_trans_huge_or_clear_bad() only needs the low part + * of the pmd to be read atomically to decide if the pmd is unstable + * or not, with the only exception of when the low part of the pmd is + * zero in which case we return a none pmd. */ -#ifndef CONFIG_TRANSPARENT_HUGEPAGE static inline pmd_t pmd_read_atomic(pmd_t *pmdp) { pmdval_t ret; @@ -74,12 +84,6 @@ static inline pmd_t pmd_read_atomic(pmd_t *pmdp) return (pmd_t) { ret }; } -#else /* CONFIG_TRANSPARENT_HUGEPAGE */ -static inline pmd_t pmd_read_atomic(pmd_t *pmdp) -{ - return (pmd_t) { atomic64_read((atomic64_t *)pmdp) }; -} -#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ static inline void native_set_pte_atomic(pte_t *ptep, pte_t pte) { |