firewire: add a client_list_lock

This adds a client_list_lock, which only protects the device's
client_list, so that future versions of the driver can call code that
takes the card->lock while holding the client_list_lock.  Adding this
lock is much simpler than adding __ versions of all the functions that
the future version may need.  The one ordering issue is to make sure
code never takes the client_list_lock with card->lock held.  Since
client_list_lock is only used in three places, that isn't hard.

Signed-off-by: Jay Fenlason <fenlason@redhat.com>

Update fill_bus_reset_event() accordingly.  Include linux/spinlock.h.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/firewire/fw-device.h b/drivers/firewire/fw-device.h
index 8ef6ec2ca21..008a7908a86 100644
--- a/drivers/firewire/fw-device.h
+++ b/drivers/firewire/fw-device.h
@@ -23,6 +23,7 @@
 #include <linux/cdev.h>
 #include <linux/idr.h>
 #include <linux/rwsem.h>
+#include <linux/spinlock.h>
 #include <asm/atomic.h>
 
 enum fw_device_state {
@@ -64,6 +65,8 @@ struct fw_device {
 	bool cmc;
 	struct fw_card *card;
 	struct device device;
+	/* to prevent deadlocks, never take this lock with card->lock held */
+	spinlock_t client_list_lock;
 	struct list_head client_list;
 	u32 *config_rom;
 	size_t config_rom_length;