greybus: make op_cycle atomic (again)

There's no need to protect updating a connections operation id cycle
counter with the operations spinlock.   That spinlock protects
connection lists, which do not interact with the cycle counter.
All that we require is that it gets updated atomically, and we
can express that requirement in its type.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

diff --git a/drivers/staging/greybus/connection.c b/drivers/staging/greybus/connection.c
index 7fbfcdc..e59a777 100644 (file)
--- a/drivers/staging/greybus/connection.c
+++ b/drivers/staging/greybus/connection.c
@@ -191,6 +191,7 @@ struct gb_connection *gb_connection_create(struct gb_interface *interface,
        list_add_tail(&connection->interface_links, &interface->connections);
        spin_unlock_irq(&gb_connections_lock);
 
+       atomic_set(&connection->op_cycle, 0);
        INIT_LIST_HEAD(&connection->operations);
 
        return connection;

diff --git a/drivers/staging/greybus/connection.h b/drivers/staging/greybus/connection.h
index 035fced..7568161 100644 (file)
--- a/drivers/staging/greybus/connection.h
+++ b/drivers/staging/greybus/connection.h
@@ -35,7 +35,7 @@ struct gb_connection {
 
        enum gb_connection_state        state;
 
-       u16                             op_cycle;
+       atomic_t                        op_cycle;
        struct list_head                operations;
 
        void                            *private;

diff --git a/drivers/staging/greybus/operation.c b/drivers/staging/greybus/operation.c
index 6ed1d47..15a6e3b 100644 (file)
--- a/drivers/staging/greybus/operation.c
+++ b/drivers/staging/greybus/operation.c
@@ -640,6 +640,7 @@ int gb_operation_request_send(struct gb_operation *operation,
        struct gb_connection *connection = operation->connection;
        struct gb_operation_msg_hdr *header;
        unsigned long timeout;
+       unsigned int cycle;
        int ret;
 
        if (connection->state != GB_CONNECTION_STATE_ENABLED)
@@ -661,9 +662,8 @@ int gb_operation_request_send(struct gb_operation *operation,
         * Assign the operation's id, and store it in the request header.
         * Zero is a reserved operation id.
         */
-       spin_lock_irq(&gb_operations_lock);
-       operation->id = ++connection->op_cycle % U16_MAX + 1;
-       spin_unlock_irq(&gb_operations_lock);
+       cycle = (unsigned int)atomic_inc_return(&connection->op_cycle);
+       operation->id = (u16)(cycle % U16_MAX + 1);
        header = operation->request->header;
        header->operation_id = cpu_to_le16(operation->id);