fault_in_readable() and fault_in_writeable() perform __get_user()
and __put_user() in a loop, implying multiple user access
locking/unlocking.
To avoid that, use user access blocks.
Cc: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
mm/gup.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index 2c51e9748a6a..be2a41feec7d 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1672,21 +1672,22 @@ size_t fault_in_writeable(char __user *uaddr, size_t size)
if (unlikely(size == 0))
return 0;
+ if (!user_write_access_begin(uaddr, size))
+ return size;
if (!PAGE_ALIGNED(uaddr)) {
- if (unlikely(__put_user(0, uaddr) != 0))
- return size;
+ unsafe_put_user(0, uaddr, out);
uaddr = (char __user *)PAGE_ALIGN((unsigned long)uaddr);
}
end = (char __user *)PAGE_ALIGN((unsigned long)start + size);
if (unlikely(end < start))
end = NULL;
while (uaddr != end) {
- if (unlikely(__put_user(0, uaddr) != 0))
- goto out;
+ unsafe_put_user(0, uaddr, out);
uaddr += PAGE_SIZE;
}
out:
+ user_write_access_end();
if (size > uaddr - start)
return size - (uaddr - start);
return 0;
@@ -1771,21 +1772,22 @@ size_t fault_in_readable(const char __user *uaddr, size_t size)
if (unlikely(size == 0))
return 0;
+ if (!user_read_access_begin(uaddr, size))
+ return size;
if (!PAGE_ALIGNED(uaddr)) {
- if (unlikely(__get_user(c, uaddr) != 0))
- return size;
+ unsafe_get_user(c, uaddr, out);
uaddr = (const char __user *)PAGE_ALIGN((unsigned long)uaddr);
}
end = (const char __user *)PAGE_ALIGN((unsigned long)start + size);
if (unlikely(end < start))
end = NULL;
while (uaddr != end) {
- if (unlikely(__get_user(c, uaddr) != 0))
- goto out;
+ unsafe_get_user(c, uaddr, out);
uaddr += PAGE_SIZE;
}
out:
+ user_read_access_end();
(void)c;
if (size > uaddr - start)
return size - (uaddr - start);
--
2.31.1
