tracing: Replace the per_cpu() with __this_cpu*() in trace_stack.c
The updates to the trace_active per cpu variable can be updated with the __this_cpu_*() functions as it only gets updated on the CPU that the variable is on. Thanks to Paul McKenney for suggesting __this_cpu_* instead of this_cpu_*. Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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@ -207,13 +207,12 @@ stack_trace_call(unsigned long ip, unsigned long parent_ip,
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struct ftrace_ops *op, struct pt_regs *pt_regs)
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struct ftrace_ops *op, struct pt_regs *pt_regs)
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{
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{
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unsigned long stack;
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unsigned long stack;
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int cpu;
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preempt_disable_notrace();
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preempt_disable_notrace();
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cpu = raw_smp_processor_id();
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/* no atomic needed, we only modify this variable by this cpu */
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/* no atomic needed, we only modify this variable by this cpu */
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if (per_cpu(trace_active, cpu)++ != 0)
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__this_cpu_inc(trace_active);
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if (__this_cpu_read(trace_active) != 1)
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goto out;
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goto out;
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ip += MCOUNT_INSN_SIZE;
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ip += MCOUNT_INSN_SIZE;
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@ -221,7 +220,7 @@ stack_trace_call(unsigned long ip, unsigned long parent_ip,
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check_stack(ip, &stack);
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check_stack(ip, &stack);
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out:
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out:
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per_cpu(trace_active, cpu)--;
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__this_cpu_dec(trace_active);
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/* prevent recursion in schedule */
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/* prevent recursion in schedule */
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preempt_enable_notrace();
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preempt_enable_notrace();
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}
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}
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@ -253,7 +252,6 @@ stack_max_size_write(struct file *filp, const char __user *ubuf,
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long *ptr = filp->private_data;
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long *ptr = filp->private_data;
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unsigned long val, flags;
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unsigned long val, flags;
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int ret;
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int ret;
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int cpu;
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ret = kstrtoul_from_user(ubuf, count, 10, &val);
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ret = kstrtoul_from_user(ubuf, count, 10, &val);
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if (ret)
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if (ret)
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@ -266,14 +264,13 @@ stack_max_size_write(struct file *filp, const char __user *ubuf,
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* we will cause circular lock, so we also need to increase
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* we will cause circular lock, so we also need to increase
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* the percpu trace_active here.
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* the percpu trace_active here.
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*/
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*/
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cpu = smp_processor_id();
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__this_cpu_inc(trace_active);
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per_cpu(trace_active, cpu)++;
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arch_spin_lock(&stack_trace_max_lock);
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arch_spin_lock(&stack_trace_max_lock);
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*ptr = val;
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*ptr = val;
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arch_spin_unlock(&stack_trace_max_lock);
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arch_spin_unlock(&stack_trace_max_lock);
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per_cpu(trace_active, cpu)--;
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__this_cpu_dec(trace_active);
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local_irq_restore(flags);
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local_irq_restore(flags);
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return count;
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return count;
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@ -307,12 +304,9 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
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static void *t_start(struct seq_file *m, loff_t *pos)
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static void *t_start(struct seq_file *m, loff_t *pos)
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{
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{
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int cpu;
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local_irq_disable();
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local_irq_disable();
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cpu = smp_processor_id();
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__this_cpu_inc(trace_active);
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per_cpu(trace_active, cpu)++;
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arch_spin_lock(&stack_trace_max_lock);
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arch_spin_lock(&stack_trace_max_lock);
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@ -324,12 +318,9 @@ static void *t_start(struct seq_file *m, loff_t *pos)
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static void t_stop(struct seq_file *m, void *p)
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static void t_stop(struct seq_file *m, void *p)
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{
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{
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int cpu;
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arch_spin_unlock(&stack_trace_max_lock);
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arch_spin_unlock(&stack_trace_max_lock);
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cpu = smp_processor_id();
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__this_cpu_dec(trace_active);
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per_cpu(trace_active, cpu)--;
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local_irq_enable();
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local_irq_enable();
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}
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}
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