diff options
| -rw-r--r-- | arch/x86/kernel/ds.c | 72 |
1 files changed, 41 insertions, 31 deletions
diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c index 5cd137a..f03f117 100644 --- a/arch/x86/kernel/ds.c +++ b/arch/x86/kernel/ds.c @@ -193,12 +193,28 @@ static DEFINE_SPINLOCK(ds_lock); */ static atomic_t tracers = ATOMIC_INIT(0); -static inline void get_tracer(struct task_struct *task) +static inline int get_tracer(struct task_struct *task) { - if (task) + int error; + + spin_lock_irq(&ds_lock); + + if (task) { + error = -EPERM; + if (atomic_read(&tracers) < 0) + goto out; atomic_inc(&tracers); - else + } else { + error = -EPERM; + if (atomic_read(&tracers) > 0) + goto out; atomic_dec(&tracers); + } + + error = 0; +out: + spin_unlock_irq(&ds_lock); + return error; } static inline void put_tracer(struct task_struct *task) @@ -209,14 +225,6 @@ static inline void put_tracer(struct task_struct *task) atomic_inc(&tracers); } -static inline int check_tracer(struct task_struct *task) -{ - return task ? - (atomic_read(&tracers) >= 0) : - (atomic_read(&tracers) <= 0); -} - - /* * The DS context is either attached to a thread or to a cpu: * - in the former case, the thread_struct contains a pointer to the @@ -677,6 +685,10 @@ struct bts_tracer *ds_request_bts(struct task_struct *task, if (ovfl) goto out; + error = get_tracer(task); + if (error < 0) + goto out; + /* * Per-cpu tracing is typically requested using smp_call_function(). * We must not sleep. @@ -684,7 +696,7 @@ struct bts_tracer *ds_request_bts(struct task_struct *task, error = -ENOMEM; tracer = kzalloc(sizeof(*tracer), GFP_ATOMIC); if (!tracer) - goto out; + goto out_put_tracer; tracer->ovfl = ovfl; error = ds_request(&tracer->ds, &tracer->trace.ds, @@ -696,13 +708,8 @@ struct bts_tracer *ds_request_bts(struct task_struct *task, spin_lock_irqsave(&ds_lock, irq); error = -EPERM; - if (!check_tracer(task)) - goto out_unlock; - get_tracer(task); - - error = -EPERM; if (tracer->ds.context->bts_master) - goto out_put_tracer; + goto out_unlock; tracer->ds.context->bts_master = tracer; spin_unlock_irqrestore(&ds_lock, irq); @@ -716,13 +723,13 @@ struct bts_tracer *ds_request_bts(struct task_struct *task, return tracer; - out_put_tracer: - put_tracer(task); out_unlock: spin_unlock_irqrestore(&ds_lock, irq); ds_put_context(tracer->ds.context); out_tracer: kfree(tracer); + out_put_tracer: + put_tracer(task); out: return ERR_PTR(error); } @@ -741,6 +748,10 @@ struct pebs_tracer *ds_request_pebs(struct task_struct *task, if (ovfl) goto out; + error = get_tracer(task); + if (error < 0) + goto out; + /* * Per-cpu tracing is typically requested using smp_call_function(). * We must not sleep. @@ -748,7 +759,7 @@ struct pebs_tracer *ds_request_pebs(struct task_struct *task, error = -ENOMEM; tracer = kzalloc(sizeof(*tracer), GFP_ATOMIC); if (!tracer) - goto out; + goto out_put_tracer; tracer->ovfl = ovfl; error = ds_request(&tracer->ds, &tracer->trace.ds, @@ -759,13 +770,8 @@ struct pebs_tracer *ds_request_pebs(struct task_struct *task, spin_lock_irqsave(&ds_lock, irq); error = -EPERM; - if (!check_tracer(task)) - goto out_unlock; - get_tracer(task); - - error = -EPERM; if (tracer->ds.context->pebs_master) - goto out_put_tracer; + goto out_unlock; tracer->ds.context->pebs_master = tracer; spin_unlock_irqrestore(&ds_lock, irq); @@ -775,13 +781,13 @@ struct pebs_tracer *ds_request_pebs(struct task_struct *task, return tracer; - out_put_tracer: - put_tracer(task); out_unlock: spin_unlock_irqrestore(&ds_lock, irq); ds_put_context(tracer->ds.context); out_tracer: kfree(tracer); + out_put_tracer: + put_tracer(task); out: return ERR_PTR(error); } @@ -804,8 +810,8 @@ void ds_release_bts(struct bts_tracer *tracer) if (task && (task != current)) wait_task_context_switch(task); - put_tracer(task); ds_put_context(tracer->ds.context); + put_tracer(task); kfree(tracer); } @@ -861,16 +867,20 @@ void ds_resume_bts(struct bts_tracer *tracer) void ds_release_pebs(struct pebs_tracer *tracer) { + struct task_struct *task; + if (!tracer) return; + task = tracer->ds.context->task; + ds_suspend_pebs(tracer); WARN_ON_ONCE(tracer->ds.context->pebs_master != tracer); tracer->ds.context->pebs_master = NULL; - put_tracer(tracer->ds.context->task); ds_put_context(tracer->ds.context); + put_tracer(task); kfree(tracer); } |