With per-resource mutexes, mulitple threads can call resource_request()
which can cause get_user() to concurrently allocate from the static pool.
Take the res_mutex when allocating from the static pool, which is used
in resouce_request() and resource_release() to guard against this.
Signed-off-by: Mike Chan <m...@android.com>
---
arch/arm/plat-omap/resource.c | 55 +++++++++++++++++++++++-----------------
1 files changed, 32 insertions(+), 23 deletions(-)
diff --git a/arch/arm/plat-omap/resource.c b/arch/arm/plat-omap/resource.c
index 0a7b79b..f769f7c 100644
--- a/arch/arm/plat-omap/resource.c
+++ b/arch/arm/plat-omap/resource.c
@@ -148,34 +148,39 @@ static struct users_list *get_user(void)
int ind = 0;
struct users_list *user;
+ /*
+ * When allocating from the static pool, we must lock resource mutex,
+ * to protect against concurrent get_user() calls.
+ */
+ down(&res_mutex);
/* See if something available in the static pool */
while (ind < MAX_USERS) {
- if (usr_list[ind].usage == UNUSED)
- break;
- else
- ind++;
+ if (usr_list[ind].usage == UNUSED) {
+ /* Pick from the static pool */
+ user = &usr_list[ind];
+ user->usage = STATIC_ALLOC;
+ up(&res_mutex);
+ return user;
+ }
+ ind++;
}
- if (ind < MAX_USERS) {
- /* Pick from the static pool */
- user = &usr_list[ind];
- user->usage = STATIC_ALLOC;
- } else {
- /* By this time we hope slab is initialized */
- if (slab_is_available()) {
- user = kmalloc(sizeof(struct users_list), GFP_KERNEL);
- if (!user) {
- printk(KERN_ERR "SRF:FATAL ERROR: kmalloc"
- "failed\n");
- return ERR_PTR(-ENOMEM);
- }
- user->usage = DYNAMIC_ALLOC;
- } else {
- /* Dynamic alloc not available yet */
- printk(KERN_ERR "SRF: FATAL ERROR: users_list"
- "initial POOL EMPTY before slab init\n");
+ up(&res_mutex);
+ /* By this time we hope slab is initialized */
+ if (slab_is_available()) {
+ user = kmalloc(sizeof(struct users_list), GFP_KERNEL);
+ if (!user) {
+ printk(KERN_ERR "SRF:FATAL ERROR: kmalloc"
+ "failed\n");
return ERR_PTR(-ENOMEM);
}
+ user->usage = DYNAMIC_ALLOC;
+ } else {
+ /* Dynamic alloc not available yet */
+ printk(KERN_ERR "SRF: FATAL ERROR: users_list"
+ "initial POOL EMPTY before slab init\n");
+ return ERR_PTR(-ENOMEM);
}
+
return user;
}
@@ -192,8 +197,12 @@ void free_user(struct users_list *user)
if (user->usage == DYNAMIC_ALLOC) {
kfree(user);
} else {
- user->usage = UNUSED;
+ /*
+ * It is not necesssary to lock when returning to the
+ * static pool.
+ */
user->dev = NULL;
+ user->usage = UNUSED;
}
}
--
1.7.0.1
--
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