linux-kernel - [PATCH 4/4] samples/kretprobe: fix the wrong type

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Date:	Wed, 25 May 2016 10:24:43 +0800
From:	Huang Shijie <shijie.huang@....com>
To:	<akpm@...ux-foundation.org>
CC:	<pmladek@...e.com>, <linux-kernel@...r.kernel.org>, <nd@....com>,
	<steve.capper@....com>, Huang Shijie <shijie.huang@....com>
Subject: [PATCH 4/4] samples/kretprobe: fix the wrong type

The regs_return_value() returns "unsigned long" or "long" value.
But the retval is int type now, it may cause overflow, the log may
becomes:
    .................
    [ 2911.078869] do_brk returned -2003877888 and took 4620 ns to execute
    ................

This patch converts the retval to "unsigned long" type, and fix the
overflow issue.

Signed-off-by: Huang Shijie <shijie.huang@....com>
---
 samples/kprobes/kretprobe_example.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/samples/kprobes/kretprobe_example.c b/samples/kprobes/kretprobe_example.c
index adc83e9..7f9060f 100644
--- a/samples/kprobes/kretprobe_example.c
+++ b/samples/kprobes/kretprobe_example.c
@@ -55,14 +55,14 @@ static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
  */
 static int ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
 {
-	int retval = regs_return_value(regs);
+	unsigned long retval = regs_return_value(regs);
 	struct my_data *data = (struct my_data *)ri->data;
 	s64 delta;
 	ktime_t now;
 
 	now = ktime_get();
 	delta = ktime_to_ns(ktime_sub(now, data->entry_stamp));
-	pr_info("%s returned %d and took %lld ns to execute\n",
+	pr_info("%s returned %lu and took %lld ns to execute\n",
 			func_name, retval, (long long)delta);
 	return 0;
 }
-- 
2.5.5