David Hildenbrand
2021-Aug-11 20:36 UTC
[PATCH v1 3/3] kernel/resource: cleanup and optimize iomem_is_exclusive()
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 at redhat.com>
---
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 ;) {
/*
* We can probably skip the resources without
* IORESOURCE_IO attribute?
*/
if (p->start >= addr + size)
break;
- if (p->end < addr)
+ if (p->end < addr) {
+ /* No need to consider children */
+ p = next_resource_skip_children(p);
continue;
+ }
+
/*
* A resource is exclusive if IORESOURCE_EXCLUSIVE is set
* or CONFIG_IO_STRICT_DEVMEM is enabled and the
* resource is busy.
*/
- if ((p->flags & IORESOURCE_BUSY) == 0)
- continue;
- if (IS_ENABLED(CONFIG_IO_STRICT_DEVMEM)
- || p->flags & IORESOURCE_EXCLUSIVE) {
+ if (p->flags & IORESOURCE_BUSY &&
+ (IS_ENABLED(CONFIG_IO_STRICT_DEVMEM) ||
+ p->flags & IORESOURCE_EXCLUSIVE)) {
err = true;
break;
}
+ p = next_resource(p);
}
read_unlock(&resource_lock);
--
2.31.1
Andy Shevchenko
2021-Aug-11 20:47 UTC
[PATCH v1 3/3] kernel/resource: cleanup and optimize iomem_is_exclusive()
On Wednesday, August 11, 2021, David Hildenbrand <david at redhat.com> 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 at redhat.com> > --- > 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 ;) {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; ...) {> /* > * We can probably skip the resources without > * IORESOURCE_IO attribute? > */ > if (p->start >= addr + size) > break; > - if (p->end < addr) > + if (p->end < addr) { > + /* No need to consider children */ > + p = next_resource_skip_children(p); > continue; > + } > + > /* > * A resource is exclusive if IORESOURCE_EXCLUSIVE is set > * or CONFIG_IO_STRICT_DEVMEM is enabled and the > * resource is busy. > */ > - if ((p->flags & IORESOURCE_BUSY) == 0) > - continue; > - if (IS_ENABLED(CONFIG_IO_STRICT_DEVMEM) > - || p->flags & IORESOURCE_EXCLUSIVE) { > + if (p->flags & IORESOURCE_BUSY && > + (IS_ENABLED(CONFIG_IO_STRICT_DEVMEM) || > + p->flags & IORESOURCE_EXCLUSIVE)) { > err = true; > break; > } > + p = next_resource(p); > } > read_unlock(&resource_lock); > > -- > 2.31.1 > >-- With Best Regards, Andy Shevchenko -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.linuxfoundation.org/pipermail/virtualization/attachments/20210811/0adb078d/attachment.html>