[PATCH 04/13] resource: Provide new functions to walk through resources

Vivek Goyal
2014-06-03T13:08:45Z

I have added two more functions to walk through resources.
Current walk_system_ram_range() deals with pfn and /proc/iomem can contain
partial pages. By dealing in pfn, callback function loses the info that
last page of a memory range is a partial page and not the full page. So
I implemented walk_system_ram_res() which returns u64 values to callback
functions and now it properly return start and end address.

walk_system_ram_range() uses find_next_system_ram() to find the next
ram resource. This in turn only travels through siblings of top level
child and does not travers through all the nodes of the resoruce tree. I
also need another function where I can walk through all the resources,
for example figure out where "GART" aperture is. Figure out where
ACPI memory is.

So I wrote another function walk_ram_res() which walks through all
/proc/iomem resources and returns matches as asked by caller. Caller
can specify "name" of resource, start and end.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Yinghai Lu <yinghai@kernel.org>
---
include/linux/ioport.h | 6 +++
kernel/resource.c | 108 +++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 110 insertions(+), 4 deletions(-)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 5e3a906..a15f7f6 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -237,6 +237,12 @@ extern int iomem_is_exclusive(u64 addr);
extern int
walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
void *arg, int (*func)(unsigned long, unsigned long, void *));
+extern int
+walk_system_ram_res(u64 start, u64 end, void *arg,
+ int (*func)(u64, u64, void *));
+extern int
+walk_ram_res(char *name, unsigned long flags, u64 start, u64 end, void *arg,
+ int (*func)(u64, u64, void *));

/* True if any part of r1 overlaps r2 */
static inline bool resource_overlaps(struct resource *r1, struct resource *r2)
diff --git a/kernel/resource.c b/kernel/resource.c
index 8957d68..b3e3f95 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -59,10 +59,8 @@ static DEFINE_RWLOCK(resource_lock);
static struct resource *bootmem_resource_free;
static DEFINE_SPINLOCK(bootmem_resource_lock);

-static void *r_next(struct seq_file *m, void *v, loff_t *pos)
+static struct resource *next_resource(struct resource *p)
{
- struct resource *p = v;
- (*pos)++;
if (p->child)
return p->child;
while (!p->sibling && p->parent)
@@ -70,6 +68,13 @@ static void *r_next(struct seq_file *m, void *v, loff_t *pos)
return p->sibling;
}

+static void *r_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ struct resource *p = v;
+ (*pos)++;
+ return (void *)next_resource(p);
+}
+
#ifdef CONFIG_PROC_FS

enum { MAX_IORES_LEVEL = 5 };
@@ -322,7 +327,71 @@ int release_resource(struct resource *old)

EXPORT_SYMBOL(release_resource);

-#if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
+/*
+ * Finds the lowest iomem reosurce exists with-in [res->start.res->end)
+ * the caller must specify res->start, res->end, res->flags and "name".
+ * If found, returns 0, res is overwritten, if not found, returns -1.
+ * This walks through whole tree and not just first level children.
+ */
+static int find_next_iomem_res(struct resource *res, char *name)
+{
+ resource_size_t start, end;
+ struct resource *p;
+
+ BUG_ON(!res);
+
+ start = res->start;
+ end = res->end;
+ BUG_ON(start >= end);
+
+ read_lock(&resource_lock);
+ p = &iomem_resource;
+ while ((p = next_resource(p))) {
+ if (p->flags != res->flags)
+ continue;
+ if (name && strcmp(p->name, name))
+ continue;
+ if (p->start > end) {
+ p = NULL;
+ break;
+ }
+ if ((p->end >= start) && (p->start < end))
+ break;
+ }
+
+ read_unlock(&resource_lock);
+ if (!p)
+ return -1;
+ /* copy data */
+ if (res->start < p->start)
+ res->start = p->start;
+ if (res->end > p->end)
+ res->end = p->end;
+ return 0;
+}
+
+int walk_ram_res(char *name, unsigned long flags, u64 start, u64 end,
+ void *arg, int (*func)(u64, u64, void *))
+{
+ struct resource res;
+ u64 orig_end;
+ int ret = -1;
+
+ res.start = start;
+ res.end = end;
+ res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+ orig_end = res.end;
+ while ((res.start < res.end) &&
+ (find_next_iomem_res(&res, name) >= 0)) {
+ ret = (*func)(res.start, res.end, arg);
+ if (ret)
+ break;
+ res.start = res.end + 1;
+ res.end = orig_end;
+ }
+ return ret;
+}
+
/*
* Finds the lowest memory reosurce exists within [res->start.res->end)
* the caller must specify res->start, res->end, res->flags and "name".
@@ -367,6 +436,37 @@ static int find_next_system_ram(struct resource *res, char *name)
/*
* This function calls callback against all memory range of "System RAM"
* which are marked as IORESOURCE_MEM and IORESOUCE_BUSY.
+ * Now, this function is only for "System RAM". This function deals with
+ * full ranges and not pfn. If resources are not pfn aligned, dealing
+ * with pfn can truncate ranges.
+ */
+int walk_system_ram_res(u64 start, u64 end, void *arg,
+ int (*func)(u64, u64, void *))
+{
+ struct resource res;
+ u64 orig_end;
+ int ret = -1;
+
+ res.start = start;
+ res.end = end;
+ res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+ orig_end = res.end;
+ while ((res.start < res.end) &&
+ (find_next_system_ram(&res, "System RAM") >= 0)) {
+ ret = (*func)(res.start, res.end, arg);
+ if (ret)
+ break;
+ res.start = res.end + 1;
+ res.end = orig_end;
+ }
+ return ret;
+}
+
+#if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
+
+/*
+ * This function calls callback against all memory range of "System RAM"
+ * which are marked as IORESOURCE_MEM and IORESOUCE_BUSY.
* Now, this function is only for "System RAM".
*/
int walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
--
1.9.0