Re: [PATCH v1 3/3] kernel/resource: remove first_lvl / siblings_only logic

From: David Hildenbrand
Date: Tue Mar 23 2021 - 07:20:06 EST

On 23.03.21 12:11, Andy Shevchenko wrote:
On Mon, Mar 22, 2021 at 05:02:00PM +0100, David Hildenbrand wrote:
All IORESOURCE_SYSTEM_RAM and IORESOURCE_MEM now properly consider the
whole resource tree, not just the first level. Let's drop the unused
first_lvl / siblings_only logic.

All functions properly search the whole tree, so remove documentation
that indicates that some functions behave differently.


Like this clean up!
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

Although a few nit-picks below.

Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
Cc: Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Keith Busch <keith.busch@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Qian Cai <cai@xxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: Brijesh Singh <brijesh.singh@xxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: kexec@xxxxxxxxxxxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
kernel/resource.c | 45 ++++++++++++---------------------------------
1 file changed, 12 insertions(+), 33 deletions(-)

diff --git a/kernel/resource.c b/kernel/resource.c
index 16e0c7e8ed24..7e00239a023a 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -64,12 +64,8 @@ static DEFINE_RWLOCK(resource_lock);
static struct resource *bootmem_resource_free;
static DEFINE_SPINLOCK(bootmem_resource_lock);
-static struct resource *next_resource(struct resource *p, bool sibling_only)
+static struct resource *next_resource(struct resource *p)
{
- /* Caller wants to traverse through siblings only */
- if (sibling_only)
- return p->sibling;
-
if (p->child)
return p->child;
while (!p->sibling && p->parent)
@@ -81,7 +77,7 @@ static void *r_next(struct seq_file *m, void *v, loff_t *pos)
{
struct resource *p = v;
(*pos)++;
- return (void *)next_resource(p, false);
+ return (void *)next_resource(p);
}
#ifdef CONFIG_PROC_FS
@@ -330,14 +326,10 @@ EXPORT_SYMBOL(release_resource);
* of the resource that's within [@start..@end]; if none is found, returns
* -ENODEV. Returns -EINVAL for invalid parameters.
*
- * This function walks the whole tree and not just first level children
- * unless @first_lvl is true.
- *
* @start: start address of the resource searched for
* @end: end address of same resource
* @flags: flags which the resource must have
* @desc: descriptor the resource must have
- * @first_lvl: walk only the first level children, if set
* @res: return ptr, if resource found
*
* The caller must specify @start, @end, @flags, and @desc
@@ -345,9 +337,8 @@ EXPORT_SYMBOL(release_resource);
*/
static int find_next_iomem_res(resource_size_t start, resource_size_t end,
unsigned long flags, unsigned long desc,
- bool first_lvl, struct resource *res)
+ struct resource *res)
{
- bool siblings_only = true;
struct resource *p;
if (!res)
@@ -358,7 +349,7 @@ static int find_next_iomem_res(resource_size_t start, resource_size_t end,
read_lock(&resource_lock);
- for (p = iomem_resource.child; p; p = next_resource(p, siblings_only)) {
+ for (p = iomem_resource.child; p; p = next_resource(p)) {
/* If we passed the resource we are looking for, stop */
if (p->start > end) {
p = NULL;
@@ -369,13 +360,6 @@ static int find_next_iomem_res(resource_size_t start, resource_size_t end,
if (p->end < start)
continue;
- /*
- * Now that we found a range that matches what we look for,
- * check the flags and the descriptor. If we were not asked to
- * use only the first level, start looking at children as well.
- */
- siblings_only = first_lvl;
-
if ((p->flags & flags) != flags)
continue;
if ((desc != IORES_DESC_NONE) && (desc != p->desc))
@@ -402,14 +386,14 @@ static int find_next_iomem_res(resource_size_t start, resource_size_t end,
static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end,
unsigned long flags, unsigned long desc,
- bool first_lvl, void *arg,

+ void *arg,
int (*func)(struct resource *, void *))

Can it be one line?

{
struct resource res;
int ret = -EINVAL;
while (start < end &&
- !find_next_iomem_res(start, end, flags, desc, first_lvl, &res)) {
+ !find_next_iomem_res(start, end, flags, desc, &res)) {
ret = (*func)(&res, arg);
if (ret)
break;
@@ -431,7 +415,6 @@ static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end,
* @arg: function argument for the callback @func
* @func: callback function that is called for each qualifying resource area
*
- * This walks through whole tree and not just first level children.
* All the memory ranges which overlap start,end and also match flags and
* desc are valid candidates.
*
@@ -441,7 +424,7 @@ static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end,
int walk_iomem_res_desc(unsigned long desc, unsigned long flags, u64 start,
u64 end, void *arg, int (*func)(struct resource *, void *))
{
- return __walk_iomem_res_desc(start, end, flags, desc, false, arg, func);
+ return __walk_iomem_res_desc(start, end, flags, desc, arg, func);
}
EXPORT_SYMBOL_GPL(walk_iomem_res_desc);
@@ -457,8 +440,8 @@ int walk_system_ram_res(u64 start, u64 end, void *arg,
{
unsigned long flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
- return __walk_iomem_res_desc(start, end, flags, IORES_DESC_NONE, false,
- arg, func);

+ return __walk_iomem_res_desc(start, end, flags, IORES_DESC_NONE, arg,
+ func);

I guess you may do it on one line.

}
/*
@@ -470,17 +453,14 @@ int walk_mem_res(u64 start, u64 end, void *arg,
{
unsigned long flags = IORESOURCE_MEM | IORESOURCE_BUSY;
- return __walk_iomem_res_desc(start, end, flags, IORES_DESC_NONE, false,
- arg, func);
+ return __walk_iomem_res_desc(start, end, flags, IORES_DESC_NONE, arg,
+ func);

Ditto.

To all your comments:

"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"

I don't think it significantly increases readability.


--
Thanks,

David / dhildenb