On Thursday, August 12, 2021, David Hildenbrand <david@xxxxxxxxxx> wrote:
On 11.08.21 22:47, Andy Shevchenko wrote:
On Wednesday, August 11, 2021, David Hildenbrand <david@xxxxxxxxxx <mailto:david@xxxxxxxxxx>> wrote:
Let's clean it up a bit, removing the unnecessary usage of r_next() by
next_resource(), and use next_range_resource() in case we are not
interested in a certain subtree.
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx
<mailto:david@xxxxxxxxxx>>
---
kernel/resource.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/kernel/resource.c b/kernel/resource.c
index 2938cf520ca3..ea853a075a83 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1754,9 +1754,8 @@ static int strict_iomem_checks;
*/
bool iomem_is_exclusive(u64 addr)
{
- struct resource *p = &iomem_resource;
+ struct resource *p;
bool err = false;
- loff_t l;
int size = PAGE_SIZE;
if (!strict_iomem_checks)
@@ -1765,27 +1764,31 @@ bool iomem_is_exclusive(u64 addr)
addr = addr & PAGE_MASK;
read_lock(&resource_lock);
- for (p = p->child; p ; p = r_next(NULL, p, &l)) {
+ for (p = iomem_resource.child; p ;) {
Hi Andy,
I consider the ordinal part of p initialization is slightly better and done outside of read lock.
Something like
p= &iomem_res...;
read lock
for (p = p->child; ...) {
Why should we care about doing that outside of the lock? That smells like a micro-optimization the compiler will most probably overwrite either way as the address of iomem_resource is just constant?
Also, for me it's much more readable and compact if we perform a single initialization instead of two separate ones in this case.
We're using the pattern I use in, find_next_iomem_res() and __region_intersects(), while we use the old pattern in iomem_map_sanity_check(), where we also use the same unnecessary r_next() call.
I might just cleanup iomem_map_sanity_check() in a similar way.
Yes, it’s like micro optimization. If you want your way I suggest then to add a macro
#define for_each_iomem_resource_child() \
for (iomem_resource...)
Thanks,
David / dhildenb
--
With Best Regards,
Andy Shevchenko
