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-rw-r--r--arch/x86/kernel/ds.c61
1 files changed, 28 insertions, 33 deletions
diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c
index dc1e7123ea4..98d271e60e0 100644
--- a/arch/x86/kernel/ds.c
+++ b/arch/x86/kernel/ds.c
@@ -232,53 +232,45 @@ static DEFINE_PER_CPU(struct ds_context *, system_context_array);
#define system_context per_cpu(system_context_array, smp_processor_id())
-static struct ds_context *ds_get_context(struct task_struct *task)
+
+static inline struct ds_context *ds_get_context(struct task_struct *task)
{
struct ds_context **p_context =
(task ? &task->thread.ds_ctx : &system_context);
- struct ds_context *context = *p_context;
+ struct ds_context *context = NULL;
+ struct ds_context *new_context = NULL;
unsigned long irq;
- if (!context) {
- context = kzalloc(sizeof(*context), GFP_KERNEL);
- if (!context)
- return NULL;
-
- spin_lock_irqsave(&ds_lock, irq);
-
- if (*p_context) {
- kfree(context);
+ /* Chances are small that we already have a context. */
+ new_context = kzalloc(sizeof(*new_context), GFP_KERNEL);
+ if (!new_context)
+ return NULL;
- context = *p_context;
- } else {
- *p_context = context;
+ spin_lock_irqsave(&ds_lock, irq);
- context->this = p_context;
- context->task = task;
+ context = *p_context;
+ if (!context) {
+ context = new_context;
- if (task)
- set_tsk_thread_flag(task, TIF_DS_AREA_MSR);
+ context->this = p_context;
+ context->task = task;
+ context->count = 0;
- if (!task || (task == current))
- wrmsrl(MSR_IA32_DS_AREA,
- (unsigned long)context->ds);
- }
+ if (task)
+ set_tsk_thread_flag(task, TIF_DS_AREA_MSR);
- context->count++;
+ if (!task || (task == current))
+ wrmsrl(MSR_IA32_DS_AREA, (unsigned long)context->ds);
- spin_unlock_irqrestore(&ds_lock, irq);
- } else {
- spin_lock_irqsave(&ds_lock, irq);
+ *p_context = context;
+ }
- context = *p_context;
- if (context)
- context->count++;
+ context->count++;
- spin_unlock_irqrestore(&ds_lock, irq);
+ spin_unlock_irqrestore(&ds_lock, irq);
- if (!context)
- context = ds_get_context(task);
- }
+ if (context != new_context)
+ kfree(new_context);
return context;
}
@@ -492,6 +484,9 @@ static int bts_read(struct bts_tracer *tracer, const void *at,
out->qualifier = bts_branch;
out->variant.lbr.from = bts_get(at, bts_from);
out->variant.lbr.to = bts_get(at, bts_to);
+
+ if (!out->variant.lbr.from && !out->variant.lbr.to)
+ out->qualifier = bts_invalid;
}
return ds_cfg.sizeof_rec[ds_bts];