[PATCH v2] crypto: atmel - Avoid flush_scheduled_work() usage

[Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>]

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/49925af7-78a8-a3dd-bce6-cfc02e1a9236@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
---
Changes in v2:
  Add a comment for built-in case to Makefile, suggested by Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

 drivers/crypto/Makefile        |  1 +
 drivers/crypto/atmel-ecc.c     |  2 +-
 drivers/crypto/atmel-i2c.c     | 24 +++++++++++++++++++++++-
 drivers/crypto/atmel-i2c.h     |  1 +
 drivers/crypto/atmel-sha204a.c |  2 +-
 5 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/drivers/crypto/Makefile b/drivers/crypto/Makefile
index 0a4fff23d272..f81703a86b98 100644
--- a/drivers/crypto/Makefile
+++ b/drivers/crypto/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_CRYPTO_DEV_ALLWINNER) += allwinner/
 obj-$(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
diff --git a/drivers/crypto/atmel-ecc.c b/drivers/crypto/atmel-ecc.c
index 333fbefbbccb..59a57279e77b 100644
--- a/drivers/crypto/atmel-ecc.c
+++ b/drivers/crypto/atmel-ecc.c
@@ -398,7 +398,7 @@ static int __init atmel_ecc_init(void)
 
 static void __exit atmel_ecc_exit(void)
 {
-	flush_scheduled_work();
+	atmel_i2c_flush_queue();
 	i2c_del_driver(&atmel_ecc_driver);
 }
 
diff --git a/drivers/crypto/atmel-i2c.c b/drivers/crypto/atmel-i2c.c
index 6fd3e969211d..226c55bfb9d6 100644
--- a/drivers/crypto/atmel-i2c.c
+++ b/drivers/crypto/atmel-i2c.c
@@ -263,6 +263,8 @@ static void atmel_i2c_work_handler(struct work_struct *work)
 	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),
@@ -272,10 +274,16 @@ void atmel_i2c_enqueue(struct atmel_i2c_work_data *work_data,
 	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)
 {
 	u32 no_of_bits = DIV_ROUND_UP(TWLO_USEC * bus_clk_rate, USEC_PER_SEC);
@@ -372,6 +380,20 @@ int atmel_i2c_probe(struct i2c_client *client, const struct i2c_device_id *id)
 }
 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 <tudor.ambarus@xxxxxxxxxxxxx>");
 MODULE_DESCRIPTION("Microchip / Atmel ECC (I2C) driver");
 MODULE_LICENSE("GPL v2");
diff --git a/drivers/crypto/atmel-i2c.h b/drivers/crypto/atmel-i2c.h
index 63b97b104f16..48929efe2a5b 100644
--- a/drivers/crypto/atmel-i2c.h
+++ b/drivers/crypto/atmel-i2c.h
@@ -173,6 +173,7 @@ void atmel_i2c_enqueue(struct atmel_i2c_work_data *work_data,
 		       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);
 
diff --git a/drivers/crypto/atmel-sha204a.c b/drivers/crypto/atmel-sha204a.c
index c96c14e7dab1..2168f877bd43 100644
--- a/drivers/crypto/atmel-sha204a.c
+++ b/drivers/crypto/atmel-sha204a.c
@@ -159,7 +159,7 @@ static int __init atmel_sha204a_init(void)
 
 static void __exit atmel_sha204a_exit(void)
 {
-	flush_scheduled_work();
+	atmel_i2c_flush_queue();
 	i2c_del_driver(&atmel_sha204a_driver);
 }
 
-- 
2.34.1