linux/drivers/firewire, branch v6.17

firewire: core: fix overlooked update of subsystem ABI version

2025-09-20T03:17:50Z

In kernel v6.5, several functions were added to the cdev layer. This required updating the default version of subsystem ABI up to 6, but this requirement was overlooked. This commit updates the version accordingly. Fixes: 6add87e9764d ("firewire: cdev: add new version of ABI to notify time stamp at request/response subaction of transaction#") Link: https://lore.kernel.org/r/20250920025148.163402-1-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: reallocate buffer for FCP address handlers when more than 4 are registered

2025-08-03T12:20:15Z

The former commit has a limitation that only up to 4 FCP address handlers could be processed per request. Although it suffices for most use cases, it is technically a regression. This commit lifts the restriction by reallocating the buffer from kernel heap when more than 4 handlers are registered. The allocation is performed within RCU read-side critical section, thus it uses GCP_ATOMIC flag. The buffer size is rounded up to the next power of two to align with kmalloc allocation units. Link: https://lore.kernel.org/r/20250803122015.236493-5-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: call FCP address handlers outside RCU read-side critical section

2025-08-03T12:20:14Z

The former commit added reference counting to ensure safe invocations of address handlers. Unlike the exclusive-region address handlers, all FCP address handlers should be called on receiving an FCP request. This commit uses the part of kernel stack to collect address handlers up to 4 within the section, then invoke them outside of the section. Reference counting ensures that each handler remains valid and safe to call. Lifting the limitation of supporting only 4 handlers is left for next work. Link: https://lore.kernel.org/r/20250803122015.236493-4-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: call handler for exclusive regions outside RCU read-side critical section

2025-08-03T12:20:13Z

The previous commit added reference counting to ensure safe invocations of address handlers. This commit moves the invocation of handlers for exclusive regions outside of the RCU read-side critical section. The address handler for the requested region is selected within the critical section, then invoked outside of it. Link: https://lore.kernel.org/r/20250803122015.236493-3-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: use reference counting to invoke address handlers safely

2025-08-11T13:22:33Z

The lifetime of address handler has been managed by linked list and RCU. This approach was introduced in commit 35202f7d8420 ("firewire: remove global lock around address handlers, convert to RCU"). The invocations of address handler are performed within RCU read-side critical sections. In commit 57e6d9f85fff ("firewire: ohci: use workqueue to handle events of AR request/response contexts"), the invocations are in a workqueue context. The approach still imposes limitation that sleeping is not allowed within RCU read-side critical sections. However, since sleeping is not permitted within RCU read-side critical sections, this approach still has a limitation. This commit adds reference counting to decouple handler invocation from handler discovery. The linked list and RCU is used to discover the handlers, while the reference counting is used to invoke them safely. Link: https://lore.kernel.org/r/20250803122015.236493-2-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: ohci: reduce the size of common context structure by extracting members into AT structure

2025-07-12T12:52:16Z

In commit 386a4153a2c1 ("firewire: ohci: cache the context run bit"), a running member was added to the context structure to cache the running state of a given DMA context. Although this member is accessible from IR, IT, and AT contexts, it is currently used only by the AT context. Additionally, the context structure includes a work item, which is also used by the AT context. Both members are unnecessary for IR and IT contexts. This commit refactors the code by moving these two members into a new structure specific to AT context. Link: https://lore.kernel.org/r/20250710131916.31289-1-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: minor code refactoring to localize table of gap count

2025-06-17T00:56:42Z

The table for gap count is accessed by a single function. In this case, it can be localized to the function. Link: https://lore.kernel.org/r/20250617004320.477421-1-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: ohci: use workqueue to handle events of AT request/response contexts

2025-06-15T13:40:29Z

This commit adds a work item to handle events of 1394 OHCI AT request/response contexts, and queues the item to the specific workqueue. The call of struct fw_packet.callbaqck() is done in the workqueue when receiving acknowledgement to the asynchronous packet transferred to remote node. Link: https://lore.kernel.org/r/20250615133253.433057-4-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: ohci: use workqueue to handle events of AR request/response contexts

2025-06-15T13:40:29Z

This commit adds a work item to handle events of 1394 OHCI AR request/response contexts, and queues the item to the specific workqueue. The call of struct fw_address_handler.address_callback() is done in the workqueue when receiving any requests from the remove nodes. Additionally, the call of struct fw_packet.callback() is done in the workqueue too when receiving acknowledge to the asynchronous packet for the response subaction of split transaction to the remote nodes. Link: https://lore.kernel.org/r/20250615133253.433057-3-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: allocate workqueue for AR/AT request/response contexts

2025-06-15T13:40:29Z

Some tasklets (softIRQs) are still used as bottom-halves to handle events for 1394 OHCI AR/AT contexts. However, using softIRQs for IRQ bottom halves is generally discouraged today. This commit adds a per-fw_card workqueue to accommodate the behaviour specified by the 1394 OHCI specification. According to the 1394 OHCI specification, system memory pages are reserved for each asynchronous DMA context. This allows concurrent operation across contexts. In the 1394 OHCI PCI driver implementation, the hardware generates IRQs either upon receiving asynchronous packets from other nodes (incoming) or after completing transmission to them (outgoing). These independent events can occur in the same transmission cycle, therefore the max_active parameter for the workqueue is set to the total number of AR/AT contexts (=4). The WQ_UNBOUND flag is used to allow the work to be scheduled on any available core, since there is little CPU cache affinity benefit for the data. Each DMA context uses a circular descriptor list in system memory, allowing deferred data processing in software as long as buffer overrun are avoided. Since the overall operation is sleepable except for small atomic regions, WQ_BH is not used. As the descriptors contain timestamps, WQ_HIGHPRI is specified to support semi-real-time processing. The asynchronous context is also used by the SCSI over IEEE 1394 protocol implementation (sbp2), which can be part of memory reclaim paths. Therefore, WQ_MEM_RECLAIM is required. To allow uses to adjust CPU affinity according to workload, WQ_SYSFS is specified so that workqueue attributes are exposed to user space. Link: https://lore.kernel.org/r/20250615133253.433057-2-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto