kernel/linux.git/include/linux/firewire.h, branch v6.18.21

firewire: core: use spin lock specific to timer for split transaction

2025-09-15T23:52:19+00:00

At present the parameters to compute timeout time for split transaction is protected by card-wide spin lock, while it is not necessarily convenient in a point to narrower critical section. This commit adds and uses another spin lock specific for the purpose. Link: https://lore.kernel.org/r/20250915234747.915922-6-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: use spin lock specific to transaction

2025-09-15T23:52:18+00:00

The list of instance for asynchronous transaction to wait for response subaction is maintained as a member of fw_card structure. The card-wide spinlock is used at present for any operation over the list, however it is not necessarily suited for the purpose. This commit adds and uses the spin lock specific to maintain the list. Link: https://lore.kernel.org/r/20250915234747.915922-5-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: use spin lock specific to topology map

2025-09-15T23:52:18+00:00

At present, the operation for read transaction to topology map register is not protected by any kind of lock primitives. This causes a potential problem to result in the mixed content of topology map. This commit adds and uses spin lock specific to topology map. Link: https://lore.kernel.org/r/20250915234747.915922-4-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: maintain phy packet receivers locally in cdev layer

2025-09-15T23:52:18+00:00

The list of receivers for phy packet is used only by cdev layer, while it is maintained as a member of fw_card structure. This commit maintains the list locally in cdev layer. Link: https://lore.kernel.org/r/20250915234747.915922-3-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

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

2025-08-11T13:22:33+00:00

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

2025-06-15T13:40:29+00:00

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

2025-06-15T13:40:29+00:00

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

firewire: core: update documentation of kernel APIs for flushing completions

2024-09-12T13:30:37+00:00

There is a slight difference between fw_iso_context_flush_completions() and fw_iso_context_schedule_flush_completions(). This commit updates the documentations for them. Link: https://lore.kernel.org/r/20240912133038.238786-5-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

Revert "firewire: core: use mutex to coordinate concurrent calls to flush completions"

2024-09-12T13:30:34+00:00

This reverts commit d9605d67562505e27dcc0f71af418118d3db91e5, since this commit is on the following reverted changes. Link: https://lore.kernel.org/r/20240912133038.238786-2-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto

firewire: core: use mutex to coordinate concurrent calls to flush completions

2024-09-09T14:00:18+00:00

In current implementation, test_and_set_bit_lock() is used to mediate concurrent calls of ohci_flush_iso_completions(). However, the ad-hoc usage of atomic operations is not preferable. This commit uses mutex_trylock() as the similar operations. The core function is responsible for the mediation, instead of 1394 OHCI driver. Link: https://lore.kernel.org/r/20240909140018.65289-3-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto