linux-kernel - [PATCH v2] iio: trigger: free trigger resource correctly

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Date:   Thu, 19 Jan 2017 19:47:38 -0800
From:   Alison Schofield <amsfield22@...il.com>
To:     jic23@...nel.org
Cc:     knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Michael.Hennerich@...log.com, gregkh@...uxfoundation.org,
        devel@...verdev.osuosl.org
Subject: [PATCH v2] iio: trigger: free trigger resource correctly

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.

Signed-off-by: Alison Schofield <amsfield22@...il.com>
---
Changes in v2:
Renamed probe jump label to say free instead of put.
Added further explanation to commit log.

Note from v1:
Patches to use devm_* funcs are ready to follow this for
the interrupt & bfin-timer triggers.


 drivers/iio/trigger/iio-trig-interrupt.c          | 8 ++++----
 drivers/iio/trigger/iio-trig-sysfs.c              | 2 +-
 drivers/staging/iio/trigger/iio-trig-bfin-timer.c | 4 ++--
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/iio/trigger/iio-trig-interrupt.c b/drivers/iio/trigger/iio-trig-interrupt.c
index 572bc6f..e18f12b 100644
--- a/drivers/iio/trigger/iio-trig-interrupt.c
+++ b/drivers/iio/trigger/iio-trig-interrupt.c
@@ -58,7 +58,7 @@ static int iio_interrupt_trigger_probe(struct platform_device *pdev)
 	trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
 	if (!trig_info) {
 		ret = -ENOMEM;
-		goto error_put_trigger;
+		goto error_free_trigger;
 	}
 	iio_trigger_set_drvdata(trig, trig_info);
 	trig_info->irq = irq;
@@ -83,8 +83,8 @@ static int iio_interrupt_trigger_probe(struct platform_device *pdev)
 	free_irq(irq, trig);
 error_free_trig_info:
 	kfree(trig_info);
-error_put_trigger:
-	iio_trigger_put(trig);
+error_free_trigger:
+	iio_trigger_free(trig);
 error_ret:
 	return ret;
 }
@@ -99,7 +99,7 @@ static int iio_interrupt_trigger_remove(struct platform_device *pdev)
 	iio_trigger_unregister(trig);
 	free_irq(trig_info->irq, trig);
 	kfree(trig_info);
-	iio_trigger_put(trig);
+	iio_trigger_free(trig);
 
 	return 0;
 }
diff --git a/drivers/iio/trigger/iio-trig-sysfs.c b/drivers/iio/trigger/iio-trig-sysfs.c
index 3dfab2b..202e8b8 100644
--- a/drivers/iio/trigger/iio-trig-sysfs.c
+++ b/drivers/iio/trigger/iio-trig-sysfs.c
@@ -174,7 +174,7 @@ static int iio_sysfs_trigger_probe(int id)
 	return 0;
 
 out2:
-	iio_trigger_put(t->trig);
+	iio_trigger_free(t->trig);
 free_t:
 	kfree(t);
 out1:
diff --git a/drivers/staging/iio/trigger/iio-trig-bfin-timer.c b/drivers/staging/iio/trigger/iio-trig-bfin-timer.c
index 9658f20..4e0b4ee 100644
--- a/drivers/staging/iio/trigger/iio-trig-bfin-timer.c
+++ b/drivers/staging/iio/trigger/iio-trig-bfin-timer.c
@@ -260,7 +260,7 @@ static int iio_bfin_tmr_trigger_probe(struct platform_device *pdev)
 out1:
 	iio_trigger_unregister(st->trig);
 out:
-	iio_trigger_put(st->trig);
+	iio_trigger_free(st->trig);
 	return ret;
 }
 
@@ -273,7 +273,7 @@ static int iio_bfin_tmr_trigger_remove(struct platform_device *pdev)
 		peripheral_free(st->t->pin);
 	free_irq(st->irq, st);
 	iio_trigger_unregister(st->trig);
-	iio_trigger_put(st->trig);
+	iio_trigger_free(st->trig);
 
 	return 0;
 }
-- 
2.1.4