linux-kernel - [PATCH 3.16 340/366] iio: iio-trig-periodic-rtc: Free trigger resource correctly

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Date:   Sun, 11 Nov 2018 19:49:05 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Jonathan Cameron" <jic23@...nel.org>,
        "Alison Schofield" <amsfield22@...il.com>,
        "Ben Hutchings" <ben.hutchings@...ethink.co.uk>
Subject: [PATCH 3.16 340/366] iio: iio-trig-periodic-rtc: Free trigger
 resource  correctly

3.16.61-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ben Hutchings <ben.hutchings@...ethink.co.uk>

This is based on upstream commit 10e840dfb0b7, which did not touch the
iio-trig-periodic-rtc driver because it has been removed upstream.

The following explanation comes from that commit:

    These stand-alone trigger drivers were using iio_trigger_put()
    where they should have been using iio_trigger_free().  The
    iio_trigger_put() adds a module_put which is bad since they
    never did a module_get.

    In the sysfs driver, module_get/put's are used as triggers are
    added & removed. This extra module_put() occurs on an error path
    in the probe routine (probably rare).

    In the bfin-timer & interrupt trigger drivers, the module resources
    are not explicitly managed, so it's doing a put on something that
    was never get'd.  It occurs on the probe error path and on the
    remove path (not so rare).

    Tested with the sysfs trigger driver.
    The bfin & interrupt drivers were build tested & inspected only.

This was build tested only.

Cc: Alison Schofield <amsfield22@...il.com>
Cc: Jonathan Cameron <jic23@...nel.org>
Signed-off-by: Ben Hutchings <ben.hutchings@...ethink.co.uk>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/staging/iio/trigger/iio-trig-periodic-rtc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/staging/iio/trigger/iio-trig-periodic-rtc.c
+++ b/drivers/staging/iio/trigger/iio-trig-periodic-rtc.c
@@ -123,7 +123,7 @@ static int iio_trig_periodic_rtc_probe(s
 		trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
 		if (!trig_info) {
 			ret = -ENOMEM;
-			goto error_put_trigger_and_remove_from_list;
+			goto error_free_trigger_and_remove_from_list;
 		}
 		iio_trigger_set_drvdata(trig, trig_info);
 		trig->ops = &iio_prtc_trigger_ops;
@@ -151,9 +151,9 @@ error_close_rtc:
 	rtc_class_close(trig_info->rtc);
 error_free_trig_info:
 	kfree(trig_info);
-error_put_trigger_and_remove_from_list:
+error_free_trigger_and_remove_from_list:
 	list_del(&trig->alloc_list);
-	iio_trigger_put(trig);
+	iio_trigger_free(trig);
 error_free_completed_registrations:
 	list_for_each_entry_safe(trig,
 				 trig2,