[PATCH linux dev-4.7 v2] drivers: fsi: Use kernel ida to manage device indexes

[Eddie James]

From: "Edward A. James" <eajames at us.ibm.com>

Fixes bad device indexes and duplicates after fsi rescan

since v1:
 * don't use the unsafe atomic counter

Signed-off-by: Edward A. James <eajames at us.ibm.com>
---
 drivers/fsi/fsi-core.c        | 10 ++++++++--
 drivers/fsi/fsi-master-gpio.c |  1 +
 drivers/fsi/fsi-scom.c        | 10 ++++++++--
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index e8a3618..d63a892 100644
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -15,6 +15,7 @@
 
 #include <linux/device.h>
 #include <linux/fsi.h>
+#include <linux/idr.h>
 #include <linux/kthread.h>
 #include <linux/module.h>
 #include <linux/slab.h>
@@ -46,7 +47,7 @@ static const int engine_page_size = 0x400;
 static struct task_struct *master_ipoll;
 static unsigned int fsi_ipoll_period_ms = 100;
 
-static atomic_t master_idx = ATOMIC_INIT(-1);
+static DEFINE_IDA(master_ida);
 
 struct fsi_slave {
 	struct list_head	list_link;	/* Master's list of slaves */
@@ -599,7 +600,7 @@ int fsi_master_register(struct fsi_master *master)
 	if (!master || !master->dev)
 		return -EINVAL;
 
-	master->idx = atomic_inc_return(&master_idx);
+	master->idx = ida_simple_get(&master_ida, 0, INT_MAX, GFP_KERNEL);
 	master->slave_list = false;
 	get_device(master->dev);
 	fsi_master_scan(master);
@@ -610,6 +611,11 @@ EXPORT_SYMBOL_GPL(fsi_master_register);
 
 void fsi_master_unregister(struct fsi_master *master)
 {
+	if (master->idx >= 0) {
+		ida_simple_remove(&master_ida, master->idx);
+		master->idx = -1;
+	}
+
 	device_remove_file(master->dev, &dev_attr_fsi_ipoll_period);
 	fsi_master_unscan(master);
 	put_device(master->dev);
diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c
index 91bdbf2..3ed82ea 100644
--- a/drivers/fsi/fsi-master-gpio.c
+++ b/drivers/fsi/fsi-master-gpio.c
@@ -512,6 +512,7 @@ static int fsi_master_gpio_probe(struct platform_device *pdev)
 	else
 		master->gpio_mux = gpio;
 
+	master->master.idx = -1;
 	master->master.n_links = 1;
 	master->master.read = fsi_master_gpio_read;
 	master->master.write = fsi_master_gpio_write;
diff --git a/drivers/fsi/fsi-scom.c b/drivers/fsi/fsi-scom.c
index a439a5e..ff8267b 100644
--- a/drivers/fsi/fsi-scom.c
+++ b/drivers/fsi/fsi-scom.c
@@ -22,6 +22,7 @@
 #include <linux/slab.h>
 #include <linux/miscdevice.h>
 #include <linux/list.h>
+#include <linux/idr.h>
 
 #define FSI_ENGID_SCOM		0x5
 
@@ -41,12 +42,14 @@ struct scom_device {
 	struct fsi_device *fsi_dev;
 	struct miscdevice mdev;
 	char	name[32];
+	int idx;
 };
 
 #define to_scom_dev(x)		container_of((x), struct scom_device, mdev)
 
 static struct list_head scom_devices;
-static atomic_t scom_idx = ATOMIC_INIT(0);
+
+static DEFINE_IDA(scom_ida);
 
 static int put_scom(struct scom_device *scom_dev, uint64_t value,
 			uint32_t addr)
@@ -187,8 +190,9 @@ static int scom_probe(struct device *dev)
 	if (!scom)
 		return -ENOMEM;
 
+	scom->idx = ida_simple_get(&scom_ida, 1, INT_MAX, GFP_KERNEL);
 	snprintf(scom->name, sizeof(scom->name),
-			"scom%d", atomic_inc_return(&scom_idx));
+			"scom%d", scom->idx);
 	scom->fsi_dev = fsi_dev;
 	scom->mdev.minor = MISC_DYNAMIC_MINOR;
 	scom->mdev.fops = &scom_fops;
@@ -211,6 +215,8 @@ static int scom_remove(struct device *dev)
 		}
 	}
 
+	ida_simple_remove(&scom_ida, scom->idx);
+
 	return 0;
 }
 
-- 
1.8.3.1