crypto: atmel - Avoid flush_scheduled_work() usage

Flushing system-wide workqueues is dangerous and will be forbidden.
Replace system_wq with local atmel_wq.

If CONFIG_CRYPTO_DEV_ATMEL_{I2C,ECC,SHA204A}=y, the ordering in Makefile
guarantees that module_init() for atmel-i2c runs before module_init()
for atmel-ecc and atmel-sha204a runs.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Tetsuo Handa <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/Makefile

···
 obj-$(CONFIG_CRYPTO_DEV_ATMEL_AES) += atmel-aes.o
 obj-$(CONFIG_CRYPTO_DEV_ATMEL_SHA) += atmel-sha.o
 obj-$(CONFIG_CRYPTO_DEV_ATMEL_TDES) += atmel-tdes.o
+# __init ordering requires atmel-i2c being before atmel-ecc and atmel-sha204a.
 obj-$(CONFIG_CRYPTO_DEV_ATMEL_I2C) += atmel-i2c.o
 obj-$(CONFIG_CRYPTO_DEV_ATMEL_ECC) += atmel-ecc.o
 obj-$(CONFIG_CRYPTO_DEV_ATMEL_SHA204A) += atmel-sha204a.o

drivers/crypto/atmel-ecc.c

···
 
 static void __exit atmel_ecc_exit(void)
 {
-	flush_scheduled_work();
+	atmel_i2c_flush_queue();
 	i2c_del_driver(&atmel_ecc_driver);
 }
 

drivers/crypto/atmel-i2c.c

···
 	work_data->cbk(work_data, work_data->areq, status);
 }
 
+static struct workqueue_struct *atmel_wq;
+
 void atmel_i2c_enqueue(struct atmel_i2c_work_data *work_data,
 		       void (*cbk)(struct atmel_i2c_work_data *work_data,
 				   void *areq, int status),
···
 	work_data->areq = areq;
 
 	INIT_WORK(&work_data->work, atmel_i2c_work_handler);
-	schedule_work(&work_data->work);
+	queue_work(atmel_wq, &work_data->work);
 }
 EXPORT_SYMBOL(atmel_i2c_enqueue);
+
+void atmel_i2c_flush_queue(void)
+{
+	flush_workqueue(atmel_wq);
+}
+EXPORT_SYMBOL(atmel_i2c_flush_queue);
 
 static inline size_t atmel_i2c_wake_token_sz(u32 bus_clk_rate)
 {
···
 	return device_sanity_check(client);
 }
 EXPORT_SYMBOL(atmel_i2c_probe);
+
+static int __init atmel_i2c_init(void)
+{
+	atmel_wq = alloc_workqueue("atmel_wq", 0, 0);
+	return atmel_wq ? 0 : -ENOMEM;
+}
+
+static void __exit atmel_i2c_exit(void)
+{
+	destroy_workqueue(atmel_wq);
+}
+
+module_init(atmel_i2c_init);
+module_exit(atmel_i2c_exit);
 
 MODULE_AUTHOR("Tudor Ambarus <[e-mail]>");
 MODULE_DESCRIPTION("Microchip / Atmel ECC (I2C) driver");

drivers/crypto/atmel-i2c.h

···
 		       void (*cbk)(struct atmel_i2c_work_data *work_data,
 				   void *areq, int status),
 		       void *areq);
+void atmel_i2c_flush_queue(void);
 
 int atmel_i2c_send_receive(struct i2c_client *client, struct atmel_i2c_cmd *cmd);
 

drivers/crypto/atmel-sha204a.c

···
 
 static void __exit atmel_sha204a_exit(void)
 {
-	flush_scheduled_work();
+	atmel_i2c_flush_queue();
 	i2c_del_driver(&atmel_sha204a_driver);
 }