[PATCH] powerpc: fix __get_user_pages_fast() irq handling

[Heiko Carstens]

__get_user_pages_fast() may be called with interrupts disabled (see e.g.
get_futex_key() in kernel/futex.c) and therefore should use local_irq_save()
and local_irq_restore() instead of local_irq_disable()/enable().

Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
---

Please note that this patch is completely untested; not even compile
tested. I just realized that there seems to be a bug when looking at
the powerpc code ;)

 arch/powerpc/mm/gup.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/gup.c b/arch/powerpc/mm/gup.c
index 6936547..c5f734e 100644
--- a/arch/powerpc/mm/gup.c
+++ b/arch/powerpc/mm/gup.c
@@ -123,6 +123,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	struct mm_struct *mm = current->mm;
 	unsigned long addr, len, end;
 	unsigned long next;
+	unsigned long flags;
 	pgd_t *pgdp;
 	int nr = 0;
 
@@ -156,7 +157,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	 * So long as we atomically load page table pointers versus teardown,
 	 * we can follow the address down to the the page and take a ref on it.
 	 */
-	local_irq_disable();
+	local_irq_save(flags);
 
 	pgdp = pgd_offset(mm, addr);
 	do {
@@ -179,7 +180,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 			break;
 	} while (pgdp++, addr = next, addr != end);
 
-	local_irq_enable();
+	local_irq_restore(flags);
 
 	return nr;
 }
-- 
1.8.3.4

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