[PATCH] iio: dummy_evgen: check iio_evgen in iio_dummy_evgen_free()

[Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>]

if iio_dummy_evgen_create() fails, iio_evgen should be NULL, when call
iio_evgen_release() to cleanup, it throws some warning and could cause
double free.

Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
---
 drivers/iio/dummy/iio_dummy_evgen.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/iio/dummy/iio_dummy_evgen.c b/drivers/iio/dummy/iio_dummy_evgen.c
index c6033e341963..2327b5f52086 100644
--- a/drivers/iio/dummy/iio_dummy_evgen.c
+++ b/drivers/iio/dummy/iio_dummy_evgen.c
@@ -58,6 +58,7 @@ static int iio_dummy_evgen_create(void)
 	ret = irq_sim_init(&iio_evgen->irq_sim, IIO_EVENTGEN_NO);
 	if (ret < 0) {
 		kfree(iio_evgen);
+		iio_evgen = NULL;
 		return ret;
 	}
 
@@ -118,6 +119,9 @@ EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs);
 
 static void iio_dummy_evgen_free(void)
 {
+	if (!iio_evgen)
+		return;
+
 	irq_sim_fini(&iio_evgen->irq_sim);
 	kfree(iio_evgen);
 }
-- 
2.20.1