On Thu, 20 May 2021, Feng Tang wrote:
> Currently the kernel_mbind() and kernel_set_mempolicy() do almost
> the same operation for parameter sanity check and preprocessing.
>
> Add a macro to unify the code to reduce the redundancy, and make
> it easier for changing the pre-processing code in future.
>
> Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
> ---
> mm/mempolicy.c | 46 +++++++++++++++++++---------------------------
> 1 file changed, 19 insertions(+), 27 deletions(-)
>
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 1964cca..0f5bf60 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1460,25 +1460,29 @@ static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode,
> return copy_to_user(mask, nodes_addr(*nodes), copy) ? -EFAULT : 0;
> }
>
> +#define MPOL_PRE_PROCESS() \
This should be extracted to helper function returning bool, not a macro.
> + \
> + nodemask_t nodes; \
> + int err; \
> + unsigned short mode_flags; \
> + mode_flags = mode & MPOL_MODE_FLAGS; \
> + mode &= ~MPOL_MODE_FLAGS; \
> + if (mode >= MPOL_MAX) \
> + return -EINVAL; \
> + if ((mode_flags & MPOL_F_STATIC_NODES) && \
> + (mode_flags & MPOL_F_RELATIVE_NODES)) \
> + return -EINVAL; \
> + err = get_nodes(&nodes, nmask, maxnode); \
> + if (err) \
> + return err;
> +
> static long kernel_mbind(unsigned long start, unsigned long len,
> unsigned long mode, const unsigned long __user *nmask,
> unsigned long maxnode, unsigned int flags)
> {
> - nodemask_t nodes;
> - int err;
> - unsigned short mode_flags;
> + MPOL_PRE_PROCESS();
>
> start = untagged_addr(start);
> - mode_flags = mode & MPOL_MODE_FLAGS;
> - mode &= ~MPOL_MODE_FLAGS;
> - if (mode >= MPOL_MAX)
> - return -EINVAL;
> - if ((mode_flags & MPOL_F_STATIC_NODES) &&
> - (mode_flags & MPOL_F_RELATIVE_NODES))
> - return -EINVAL;
> - err = get_nodes(&nodes, nmask, maxnode);
> - if (err)
> - return err;
> return do_mbind(start, len, mode, mode_flags, &nodes, flags);
> }
>
> @@ -1493,20 +1497,8 @@ SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
> static long kernel_set_mempolicy(int mode, const unsigned long __user *nmask,
> unsigned long maxnode)
> {
> - int err;
> - nodemask_t nodes;
> - unsigned short flags;
> -
> - flags = mode & MPOL_MODE_FLAGS;
> - mode &= ~MPOL_MODE_FLAGS;
> - if ((unsigned int)mode >= MPOL_MAX)
> - return -EINVAL;
> - if ((flags & MPOL_F_STATIC_NODES) && (flags & MPOL_F_RELATIVE_NODES))
> - return -EINVAL;
> - err = get_nodes(&nodes, nmask, maxnode);
> - if (err)
> - return err;
> - return do_set_mempolicy(mode, flags, &nodes);
> + MPOL_PRE_PROCESS();
> + return do_set_mempolicy(mode, mode_flags, &nodes);
> }
>
> SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
> --
> 2.7.4
>
>
