linux-kernel - [PATCH 02/13] staging: gasket: sysfs: hold reference to device while in use

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Message-Id: <20180729193646.201721-3-toddpoynor@gmail.com>
Date:   Sun, 29 Jul 2018 12:36:35 -0700
From:   Todd Poynor <toddpoynor@...il.com>
To:     Rob Springer <rspringer@...gle.com>,
        John Joseph <jnjoseph@...gle.com>,
        Ben Chan <benchan@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        Dmitry Torokhov <dtor@...omium.org>,
        Todd Poynor <toddpoynor@...gle.com>
Subject: [PATCH 02/13] staging: gasket: sysfs: hold reference to device while in use

From: Todd Poynor <toddpoynor@...gle.com>

Hold a reference to the struct device while a gasket sysfs mapping
exists for the device and a pointer to the struct is kept in the mapping
data structures.

Signed-off-by: Todd Poynor <toddpoynor@...gle.com>
---
 drivers/staging/gasket/gasket_sysfs.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/gasket/gasket_sysfs.c b/drivers/staging/gasket/gasket_sysfs.c
index da972ce0e0db0..fde04658419bc 100644
--- a/drivers/staging/gasket/gasket_sysfs.c
+++ b/drivers/staging/gasket/gasket_sysfs.c
@@ -126,6 +126,7 @@ static void put_mapping(struct gasket_sysfs_mapping *mapping)
 		kfree(mapping->attributes);
 		mapping->attributes = NULL;
 		mapping->attribute_count = 0;
+		put_device(mapping->device);
 		mapping->device = NULL;
 		mapping->gasket_dev = NULL;
 	}
@@ -208,22 +209,20 @@ int gasket_sysfs_create_mapping(
 		device->kobj.name);
 
 	mapping = &dev_mappings[map_idx];
-	kref_init(&mapping->refcount);
-	mapping->device = device;
-	mapping->gasket_dev = gasket_dev;
 	mapping->attributes = kcalloc(GASKET_SYSFS_MAX_NODES,
 				      sizeof(*mapping->attributes),
 				      GFP_KERNEL);
-	mapping->attribute_count = 0;
 	if (!mapping->attributes) {
 		dev_dbg(device, "Unable to allocate sysfs attribute array\n");
-		mapping->device = NULL;
-		mapping->gasket_dev = NULL;
 		mutex_unlock(&mapping->mutex);
 		mutex_unlock(&function_mutex);
 		return -ENOMEM;
 	}
 
+	kref_init(&mapping->refcount);
+	mapping->device = get_device(device);
+	mapping->gasket_dev = gasket_dev;
+	mapping->attribute_count = 0;
 	mutex_unlock(&mapping->mutex);
 	mutex_unlock(&function_mutex);
 
-- 
2.18.0.345.g5c9ce644c3-goog