ACCESS_ONCE does not work reliably on non-scalar types. For example gcc 4.6 and 4.7 might remove the volatile tag for such accesses during the SRA (scalar replacement of aggregates) step https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145) Let's use a barrier instead of ACCESS_ONCE to avoid that issue. Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> --- arch/mips/mm/gup.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c index 06ce17c..cb2ca51 100644 --- a/arch/mips/mm/gup.c +++ b/arch/mips/mm/gup.c @@ -17,8 +17,8 @@ static inline pte_t gup_get_pte(pte_t *ptep) { -#if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32) pte_t pte; +#if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32) retry: pte.pte_low = ptep->pte_low; @@ -30,7 +30,9 @@ retry: return pte; #else - return ACCESS_ONCE(*ptep); + pte = *ptep; + barrier(); + return pte; #endif } -- 1.9.3
