[PATCH] parisc: ftrace: get_kprobe() must be called with preempt disabled

[Helge Deller <deller@gmx.de>]

As noticed by Masami Hiramatsu, get_kprobe() must be called with preempt
disabled.

Noticed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/kernel/ftrace.c b/arch/parisc/kernel/ftrace.c
index 63e3ecb9da81..dd356ad18aca 100644
--- a/arch/parisc/kernel/ftrace.c
+++ b/arch/parisc/kernel/ftrace.c
@@ -207,13 +212,22 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 			   struct ftrace_ops *ops, struct pt_regs *regs)
 {
 	struct kprobe_ctlblk *kcb;
-	struct kprobe *p = get_kprobe((kprobe_opcode_t *)ip);
+	struct kprobe *p;
+
+	/*
+	 * We don't want to be preempted for the entire
+	 * duration of kprobe processing
+	 */
+	preempt_disable();
+	p = get_kprobe((kprobe_opcode_t *)ip);

 	if (unlikely(!p) || kprobe_disabled(p))
+		preempt_enable_no_resched();
 		return;

 	if (kprobe_running()) {
 		kprobes_inc_nmissed_count(p);
+		preempt_enable_no_resched();
 		return;
 	}

@@ -235,6 +249,8 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 		}
 	}
 	__this_cpu_write(current_kprobe, NULL);
+
+	preempt_enable_no_resched();
 }
 NOKPROBE_SYMBOL(kprobe_ftrace_handler);