firewire: don't use PREPARE_DELAYED_WORK

PREPARE_[DELAYED_]WORK() are being phased out.  They have few users
and a nasty surprise in terms of reentrancy guarantee as workqueue
considers work items to be different if they don't have the same work
function.

firewire core-device and sbp2 have been been multiplexing work items
with multiple work functions.  Introduce fw_device_workfn() and
sbp2_lu_workfn() which invoke fw_device->workfn and
sbp2_logical_unit->workfn respectively and always use the two
functions as the work functions and update the users to set the
->workfn fields instead of overriding work functions using
PREPARE_DELAYED_WORK().

This fixes a variety of possible regressions since a2c1c57be8d9
"workqueue: consider work function when searching for busy work items"
due to which fw_workqueue lost its required non-reentrancy property.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: linux1394-devel@lists.sourceforge.net
Cc: stable@vger.kernel.org # v3.9+
Cc: stable@vger.kernel.org # v3.8.2+
Cc: stable@vger.kernel.org # v3.4.60+
Cc: stable@vger.kernel.org # v3.2.40+

3 files changed, 29 insertions, 11 deletions

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index de4aa409abe2..2c6d5e118ac1 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -916,7 +916,7 @@ static int lookup_existing_device(struct device *dev, void *data)
                 old->config_rom_retries = 0;
                 fw_notice(card, "rediscovered device %s\n", dev_name(dev));
 
-                PREPARE_DELAYED_WORK(&old->work, fw_device_update);
+                old->workfn = fw_device_update;
                 fw_schedule_device_work(old, 0);
 
                 if (current_node == card->root_node)
@@ -1075,7 +1075,7 @@ static void fw_device_init(struct work_struct *work)
         if (atomic_cmpxchg(&device->state,
                            FW_DEVICE_INITIALIZING,
                            FW_DEVICE_RUNNING) == FW_DEVICE_GONE) {
-                PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown);
+                device->workfn = fw_device_shutdown;
                 fw_schedule_device_work(device, SHUTDOWN_DELAY);
         } else {
                 fw_notice(card, "created device %s: GUID %08x%08x, S%d00\n",
@@ -1196,13 +1196,20 @@ static void fw_device_refresh(struct work_struct *work)
                   dev_name(&device->device), fw_rcode_string(ret));
  gone:
         atomic_set(&device->state, FW_DEVICE_GONE);
-        PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown);
+        device->workfn = fw_device_shutdown;
         fw_schedule_device_work(device, SHUTDOWN_DELAY);
  out:
         if (node_id == card->root_node->node_id)
                 fw_schedule_bm_work(card, 0);
 }
 
+static void fw_device_workfn(struct work_struct *work)
+{
+        struct fw_device *device = container_of(to_delayed_work(work),
+                                                struct fw_device, work);
+        device->workfn(work);
+}
+
 void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
 {
         struct fw_device *device;
@@ -1252,7 +1259,8 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
                  * power-up after getting plugged in.  We schedule the
                  * first config rom scan half a second after bus reset.
                  */
-                INIT_DELAYED_WORK(&device->work, fw_device_init);
+                device->workfn = fw_device_init;
+                INIT_DELAYED_WORK(&device->work, fw_device_workfn);
                 fw_schedule_device_work(device, INITIAL_DELAY);
                 break;
 
@@ -1268,7 +1276,7 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
                 if (atomic_cmpxchg(&device->state,
                             FW_DEVICE_RUNNING,
                             FW_DEVICE_INITIALIZING) == FW_DEVICE_RUNNING) {
-                        PREPARE_DELAYED_WORK(&device->work, fw_device_refresh);
+                        device->workfn = fw_device_refresh;
                         fw_schedule_device_work(device,
                                 device->is_local ? 0 : INITIAL_DELAY);
                 }
@@ -1283,7 +1291,7 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
                 smp_wmb();  /* update node_id before generation */
                 device->generation = card->generation;
                 if (atomic_read(&device->state) == FW_DEVICE_RUNNING) {
-                        PREPARE_DELAYED_WORK(&device->work, fw_device_update);
+                        device->workfn = fw_device_update;
                         fw_schedule_device_work(device, 0);
                 }
                 break;
@@ -1308,7 +1316,7 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
                 device = node->data;
                 if (atomic_xchg(&device->state,
                                 FW_DEVICE_GONE) == FW_DEVICE_RUNNING) {
-                        PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown);
+                        device->workfn = fw_device_shutdown;
                         fw_schedule_device_work(device,
                                 list_empty(&card->link) ? 0 : SHUTDOWN_DELAY);
                 }
diff --git a/drivers/firewire/sbp2.c b/drivers/firewire/sbp2.c
index 281029daf98c..7aef911fdc71 100644
--- a/drivers/firewire/sbp2.c
+++ b/drivers/firewire/sbp2.c
@@ -146,6 +146,7 @@ struct sbp2_logical_unit {
          */
         int generation;
         int retries;
+        work_func_t workfn;
         struct delayed_work work;
         bool has_sdev;
         bool blocked;
@@ -864,7 +865,7 @@ static void sbp2_login(struct work_struct *work)
         /* set appropriate retry limit(s) in BUSY_TIMEOUT register */
         sbp2_set_busy_timeout(lu);
 
-        PREPARE_DELAYED_WORK(&lu->work, sbp2_reconnect);
+        lu->workfn = sbp2_reconnect;
         sbp2_agent_reset(lu);
 
         /* This was a re-login. */
@@ -918,7 +919,7 @@ static void sbp2_login(struct work_struct *work)
          * If a bus reset happened, sbp2_update will have requeued
          * lu->work already.  Reset the work from reconnect to login.
          */
-        PREPARE_DELAYED_WORK(&lu->work, sbp2_login);
+        lu->workfn = sbp2_login;
 }
 
 static void sbp2_reconnect(struct work_struct *work)
@@ -952,7 +953,7 @@ static void sbp2_reconnect(struct work_struct *work)
                     lu->retries++ >= 5) {
                         dev_err(tgt_dev(tgt), "failed to reconnect\n");
                         lu->retries = 0;
-                        PREPARE_DELAYED_WORK(&lu->work, sbp2_login);
+                        lu->workfn = sbp2_login;
                 }
                 sbp2_queue_work(lu, DIV_ROUND_UP(HZ, 5));
 
@@ -972,6 +973,13 @@ static void sbp2_reconnect(struct work_struct *work)
         sbp2_conditionally_unblock(lu);
 }
 
+static void sbp2_lu_workfn(struct work_struct *work)
+{
+        struct sbp2_logical_unit *lu = container_of(to_delayed_work(work),
+                                                struct sbp2_logical_unit, work);
+        lu->workfn(work);
+}
+
 static int sbp2_add_logical_unit(struct sbp2_target *tgt, int lun_entry)
 {
         struct sbp2_logical_unit *lu;
@@ -998,7 +1006,8 @@ static int sbp2_add_logical_unit(struct sbp2_target *tgt, int lun_entry)
         lu->blocked  = false;
         ++tgt->dont_block;
         INIT_LIST_HEAD(&lu->orb_list);
-        INIT_DELAYED_WORK(&lu->work, sbp2_login);
+        lu->workfn = sbp2_login;
+        INIT_DELAYED_WORK(&lu->work, sbp2_lu_workfn);
 
         list_add_tail(&lu->link, &tgt->lu_list);
         return 0;
diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index 5d7782e42b8f..c3683bdf28fe 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -200,6 +200,7 @@ struct fw_device {
         unsigned irmc:1;
         unsigned bc_implemented:2;
 
+        work_func_t workfn;
         struct delayed_work work;
         struct fw_attribute_group attribute_group;
 };