Re: [PATCH v4 4/4] mm/gup: clean up codes in fault_in_xxx() functions
From: David Hildenbrand
Date: Sun Apr 13 2025 - 16:03:13 EST
On 13.04.25 03:07, Baoquan He wrote:
On 04/11/25 at 01:41pm, David Hildenbrand wrote:
On 11.04.25 13:15, Baoquan He wrote:
On 04/11/25 at 10:54am, David Hildenbrand wrote:
On 10.04.25 05:57, Baoquan He wrote:
The code style in fault_in_readable() and fault_in_writable() is a
little inconsistent with fault_in_safe_writeable(). In fault_in_readable()
and fault_in_writable(), it uses 'uaddr' passed in as loop cursor. While
in fault_in_safe_writeable(), local variable 'start' is used as loop
cursor. This may mislead people when reading code or making change in
these codes.
Here define explicit loop cursor and use for loop to simplify codes in
these three functions. These cleanup can make them be consistent in
code style and improve readability.
Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
---
mm/gup.c | 65 +++++++++++++++++++++++---------------------------------
1 file changed, 26 insertions(+), 39 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index 77a5bc622567..a76bd7e90a71 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2113,28 +2113,24 @@ static long __get_user_pages_locked(struct mm_struct *mm, unsigned long start,
*/
size_t fault_in_writeable(char __user *uaddr, size_t size)
{
- char __user *start = uaddr, *end;
+ const unsigned long start = (unsigned long)uaddr;
+ const unsigned long end = start + size;
+ unsigned long cur = start;
I would initialize cur in the for loop header, makes the loop easier to
read.
Both is fine to me. It's to satisfy checkpatch.sh which complains about
exceeding 80 char in the line.
Did checkpatch.sh actually complain? You might be happy to learn that the
new limit is 100. :)
That's great to know. I never noticed this and always wrap via vim's
indication.
Note that coding style says:
"
The preferred limit on the length of a single line is 80 columns.
Statements longer than 80 columns should be broken into sensible chunks,
unless exceeding 80 columns significantly increases readability and does
not hide information.
"
So 80 is still recommended, but there is nothing wrong about exceeding
80 if there is good reason.
--
Cheers,
David / dhildenb