From: Chunqiu Wang <cqwang@xxxxxxxxxxxx>
Current OMAP resource fwk uses a global res_mutex
for resource_request and resource_release calls
for all the available resources.It may cause dead
lock if resource_request/resource_release is called
recursively.
For current OMAP3 VDD1/VDD2 resource, the change_level
implementation is mach-omap2/resource34xx.c/set_opp(),
when using resource_release to remove vdd1 constraint,
this function may call resource_release again to release
Vdd2 constrait if target vdd1 level is less than OPP3.
in this scenario, the global res_mutex down operation
will be called again, this will cause the second
down operation hang there.
To fix the problem, per-resource mutex is added
to avoid hangup when resource_request/resource_release
is called recursively.
Signed-off-by: Chunqiu Wang <cqwang@xxxxxxxxxxxx>
Signed-off-by: Mike Chan <mike@xxxxxxxxxxx>
---
arch/arm/plat-omap/include/plat/resource.h | 2 ++
arch/arm/plat-omap/resource.c | 21 ++++++++++-----------
2 files changed, 12 insertions(+), 11 deletions(-)
diff --git a/arch/arm/plat-omap/include/plat/resource.h b/arch/arm/plat-omap/include/plat/resource.h
index 9acebcc..b5aff1f 100644
--- a/arch/arm/plat-omap/include/plat/resource.h
+++ b/arch/arm/plat-omap/include/plat/resource.h
@@ -54,6 +54,8 @@ struct shared_resource {
/* Shared resource operations */
struct shared_resource_ops *ops;
struct list_head node;
+ /* Protect each resource */
+ struct mutex resource_mutex;
};
struct shared_resource_ops {
diff --git a/arch/arm/plat-omap/resource.c b/arch/arm/plat-omap/resource.c
index f1cdecf..0a7b79b 100644
--- a/arch/arm/plat-omap/resource.c
+++ b/arch/arm/plat-omap/resource.c
@@ -277,6 +277,7 @@ int resource_register(struct shared_resource *resp)
}
INIT_LIST_HEAD(&resp->users_list);
+ mutex_init(&resp->resource_mutex);
/* Add the resource to the resource list */
list_add(&resp->node, &res_list);
@@ -339,14 +340,13 @@ int resource_request(const char *name, struct device *dev,
struct users_list *user;
int found = 0, ret = 0;
- down(&res_mutex);
- resp = _resource_lookup(name);
+ resp = resource_lookup(name);
if (!resp) {
printk(KERN_ERR "resource_request: Invalid resource name\n");
- ret = -EINVAL;
- goto res_unlock;
+ return -EINVAL;
}
+ mutex_lock(&resp->resource_mutex);
/* Call the resource specific validate function */
if (resp->ops->validate_level) {
ret = resp->ops->validate_level(resp, level);
@@ -375,7 +375,7 @@ int resource_request(const char *name, struct device *dev,
user->level = level;
res_unlock:
- up(&res_mutex);
+ mutex_unlock(&resp->resource_mutex);
/*
* Recompute and set the current level for the resource.
* NOTE: update_resource level moved out of spin_lock, as it may call
@@ -406,14 +406,13 @@ int resource_release(const char *name, struct device *dev)
struct users_list *user;
int found = 0, ret = 0;
- down(&res_mutex);
- resp = _resource_lookup(name);
+ resp = resource_lookup(name);
if (!resp) {
printk(KERN_ERR "resource_release: Invalid resource name\n");
- ret = -EINVAL;
- goto res_unlock;
+ return -EINVAL;
}
+ mutex_lock(&resp->resource_mutex);
list_for_each_entry(user, &resp->users_list, node) {
if (user->dev == dev) {
found = 1;
@@ -434,7 +433,7 @@ int resource_release(const char *name, struct device *dev)
/* Recompute and set the current level for the resource */
ret = update_resource_level(resp);
res_unlock:
- up(&res_mutex);
+ mutex_unlock(&resp->resource_mutex);
return ret;
}
EXPORT_SYMBOL(resource_release);
@@ -458,7 +457,7 @@ int resource_get_level(const char *name)
up(&res_mutex);
return -EINVAL;
}
- ret = resp->curr_level;
+ ret = resp->curr_level;
up(&res_mutex);
return ret;
}
--
1.6.6.2
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