Re: [RFC Patch v2 2/4] mm/mempolicy: unify the preprocessing for mbind and set_mempolicy
From: Feng Tang <hidden>
Date: 2021-05-24 08:32:55
Also in:
lkml
Subsystem:
memory management, memory management - memory policy and migration, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
On Mon, May 24, 2021 at 01:59:39PM +0800, Tang, Feng wrote:
On Sun, May 23, 2021 at 10:16:11PM -0700, David Rientjes wrote:quoted
On Thu, 20 May 2021, Feng Tang wrote:quoted
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 <redacted> --- 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.Yes, initially I did try it with an inline function, but as a function it has quite several input parameters and several output parameters, which made the code still big and ugly. But if community think it's the right direction to go, I can change it.
Following is a patch to unify the preprocssing by using a helper function, please review, thanks - Feng ---
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index d79fa299b70c..8e4f47f925b6 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c@@ -1460,6 +1460,20 @@ static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode, return copy_to_user(mask, nodes_addr(*nodes), copy) ? -EFAULT : 0; } +static inline int mpol_pre_process(int *mode, const unsigned long __user *nmask, unsigned long maxnode, nodemask_t *nodes, unsigned short *flags) +{ + int ret; + + *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; + ret = get_nodes(nodes, nmask, maxnode); + return ret; +} + static long kernel_mbind(unsigned long start, unsigned long len, unsigned long mode, const unsigned long __user *nmask, unsigned long maxnode, unsigned int flags)
@@ -1467,19 +1481,14 @@ static long kernel_mbind(unsigned long start, unsigned long len, nodemask_t nodes; int err; unsigned short mode_flags; + int lmode = mode; - 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); + err = mpol_pre_process(&lmode, nmask, maxnode, &nodes, &mode_flags); if (err) return err; - return do_mbind(start, len, mode, mode_flags, &nodes, flags); + + start = untagged_addr(start); + return do_mbind(start, len, lmode, mode_flags, &nodes, flags); } SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
@@ -1495,18 +1504,14 @@ static long kernel_set_mempolicy(int mode, const unsigned long __user *nmask, { int err; nodemask_t nodes; - unsigned short flags; + unsigned short mode_flags; + int lmode = mode; - 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); + err = mpol_pre_process(&lmode, nmask, maxnode, &nodes, &mode_flags); if (err) return err; - return do_set_mempolicy(mode, flags, &nodes); + + return do_set_mempolicy(lmode, mode_flags, &nodes); } SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,