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Diffstat (limited to 'arch/x86/kernel/ds.c')
-rw-r--r--arch/x86/kernel/ds.c25
1 files changed, 21 insertions, 4 deletions
diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c
index 2b69994fd3a8..d1a121443bde 100644
--- a/arch/x86/kernel/ds.c
+++ b/arch/x86/kernel/ds.c
@@ -236,17 +236,33 @@ static inline struct ds_context *ds_alloc_context(struct task_struct *task)
struct ds_context *context = *p_context;
if (!context) {
+ spin_unlock(&ds_lock);
+
context = kzalloc(sizeof(*context), GFP_KERNEL);
- if (!context)
+ if (!context) {
+ spin_lock(&ds_lock);
return NULL;
+ }
context->ds = kzalloc(ds_cfg.sizeof_ds, GFP_KERNEL);
if (!context->ds) {
kfree(context);
+ spin_lock(&ds_lock);
return NULL;
}
+ spin_lock(&ds_lock);
+ /*
+ * Check for race - another CPU could have allocated
+ * it meanwhile:
+ */
+ if (*p_context) {
+ kfree(context->ds);
+ kfree(context);
+ return *p_context;
+ }
+
*p_context = context;
context->this = p_context;
@@ -384,14 +400,15 @@ static int ds_request(struct task_struct *task, void *base, size_t size,
spin_lock(&ds_lock);
- if (!check_tracer(task))
- return -EPERM;
-
error = -ENOMEM;
context = ds_alloc_context(task);
if (!context)
goto out_unlock;
+ error = -EPERM;
+ if (!check_tracer(task))
+ goto out_unlock;
+
error = -EALREADY;
if (context->owner[qual] == current)
goto out_unlock;