Merge tag 'firewire-updates-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394

Pull firewire updates from Takashi Sakamoto:
 "This update replaces the remaining tasklet usage in the FireWire
  subsystem with workqueue for asynchronous packet transmission. With
  this change, tasklets are now fully eliminated from the subsystem.

  Asynchronous packet transmission is used for serial bus topology
  management as well as for the operation of the SBP-2 protocol driver
  (firewire-sbp2). To ensure reliability during low-memory conditions,
  the associated workqueue is created with the WQ_MEM_RECLAIM flag,
  allowing it to participate in memory reclaim paths. Other attributes
  are aligned with those used for isochronous packet handling, which was
  migrated to workqueues in v6.12.

  The workqueues are sleepable and support preemptible work items,
  making them more suitable for real-time workloads that benefit from
  timely task preemption at the system level.

  There remains an issue where 'schedule()' may be called within an RCU
  read-side critical section, due to a direct replacement of
  'tasklet_disable_in_atomic()' with 'disable_work_sync()'. A proposed
  fix for this has been posted[1], and is currently under review and
  testing. It is expected to be sent upstream later"

Link: https://lore.kernel.org/lkml/20250728015125.17825-1-o-takashi@sakamocchi.jp/ [1]

* tag 'firewire-updates-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
  firewire: ohci: reduce the size of common context structure by extracting members into AT structure
  firewire: core: minor code refactoring to localize table of gap count
  firewire: ohci: use workqueue to handle events of AT request/response contexts
  firewire: ohci: use workqueue to handle events of AR request/response contexts
  firewire: core: allocate workqueue for AR/AT request/response contexts
  firewire: core: use from_work() macro to expand parent structure of work_struct
  firewire: ohci: use from_work() macro to expand parent structure of work_struct
  firewire: ohci: correct code comments about bus_reset tasklet

1 files changed, 10 insertions, 2 deletions

diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index b632eec3ab52..cceb70415ed2 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -136,6 +136,7 @@ struct fw_card {
 	__be32 maint_utility_register;
 
 	struct workqueue_struct *isoc_wq;
+	struct workqueue_struct *async_wq;
 };
 
 static inline struct fw_card *fw_card_get(struct fw_card *card)
@@ -307,8 +308,7 @@ struct fw_packet {
 	 * For successful transmission, the status code is the ack received
 	 * from the destination.  Otherwise it is one of the juju-specific
 	 * rcodes:  RCODE_SEND_ERROR, _CANCELLED, _BUSY, _GENERATION, _NO_ACK.
-	 * The callback can be called from tasklet context and thus
-	 * must never block.
+	 * The callback can be called from workqueue and thus must never block.
 	 */
 	fw_packet_callback_t callback;
 	int ack;
@@ -381,6 +381,10 @@ void __fw_send_request(struct fw_card *card, struct fw_transaction *t, int tcode
  *
  * A variation of __fw_send_request() to generate callback for response subaction without time
  * stamp.
+ *
+ * The callback is invoked in the workqueue context in most cases. However, if an error is detected
+ * before queueing or the destination address refers to the local node, it is invoked in the
+ * current context instead.
  */
 static inline void fw_send_request(struct fw_card *card, struct fw_transaction *t, int tcode,
 				   int destination_id, int generation, int speed,
@@ -410,6 +414,10 @@ static inline void fw_send_request(struct fw_card *card, struct fw_transaction *
  * @callback_data:	data to be passed to the transaction completion callback
  *
  * A variation of __fw_send_request() to generate callback for response subaction with time stamp.
+ *
+ * The callback is invoked in the workqueue context in most cases. However, if an error is detected
+ * before queueing or the destination address refers to the local node, it is invoked in the current
+ * context instead.
  */
 static inline void fw_send_request_with_tstamp(struct fw_card *card, struct fw_transaction *t,
 	int tcode, int destination_id, int generation, int speed, unsigned long long offset,