linux/drivers/firewire/core-cdev.c, branch v3.0

firewire: sbp2: parallelize login, reconnect, logout

2011-05-10T20:53:46Z

The struct sbp2_logical_unit.work items can all be executed in parallel but are not reentrant. Furthermore, reconnect or re-login work must be executed in a WQ_MEM_RECLAIM workqueue. Hence replace the old single-threaded firewire-sbp2 workqueue by a concurrency-managed but non-reentrant workqueue with rescuer. firewire-core already maintains one, hence use this one. In earlier versions of this change, I observed occasional failures of parallel INQUIRY to an Initio INIC-2430 FireWire 800 to dual IDE bridge. More testing indicates that parallel INQUIRY is not actually a problem, but too quick successions of logout and login + INQUIRY, e.g. a quick sequence of cable plugout and plugin, can result in failed INQUIRY. This does not seem to be something that should or could be addressed by serialization. Another dual-LU device to which I currently have access to, an OXUF924DSB FireWire 800 to dual SATA bridge with firmware from MacPower, has been successfully tested with this too. This change is beneficial to environments with two or more FireWire storage devices, especially if they are located on the same bus. Management tasks that should be performed as soon and as quickly as possible, especially reconnect, are no longer held up by tasks on other devices that may take a long time, especially login with INQUIRY and sd or sr driver probe. Signed-off-by: Stefan Richter

firewire: core: use non-reentrant workqueue with rescuer

2011-05-10T20:53:45Z

firewire-core manages the following types of work items: fw_card.br_work: - resets the bus on a card and possibly sends a PHY packet before that - does not sleep for long or not at all - is scheduled via fw_schedule_bus_reset() by - firewire-ohci's pci_probe method - firewire-ohci's set_config_rom method, called by kernelspace protocol drivers and userspace drivers which add/remove Configuration ROM descriptors - userspace drivers which use the bus reset ioctl - itself if the last reset happened less than 2 seconds ago fw_card.bm_work: - performs bus management duties - usually does not (but may in corner cases) sleep for long - is scheduled via fw_schedule_bm_work() by - firewire-ohci's self-ID-complete IRQ handler tasklet - firewire-core's fw_device.work instances whenever the root node device was (successfully or unsuccessfully) discovered, refreshed, or rediscovered - itself in case of resource allocation failures or in order to obey the 125ms bus manager arbitration interval fw_device.work: - performs node probe, update, shutdown, revival, removal; including kernel driver probe, update, shutdown and bus reset notification to userspace drivers - usually sleeps moderately long, in corner cases very long - is scheduled by - firewire-ohci's self-ID-complete IRQ handler tasklet via the core's fw_node_event - firewire-ohci's pci_remove method via core's fw_destroy_nodes/ fw_node_event - itself during retries, e.g. while a node is powering up iso_resource.work: - accesses registers at the Isochronous Resource Manager node - usually does not (but may in corner cases) sleep for long - is scheduled via schedule_iso_resource() by - the owning userspace driver at addition and removal of the resource - firewire-core's fw_device.work instances after bus reset - itself in case of resource allocation if necessary to obey the 1000ms reallocation period after bus reset fw_card.br_work instances should not, and instances of the others must not, be executed in parallel by multiple CPUs -- but were not protected against that. Hence allocate a non-reentrant workqueue for them. fw_device.work may be used in the memory reclaim path in case of SBP-2 device updates. Hence we need a workqueue with rescuer and cannot use system_nrt_wq. Signed-off-by: Stefan Richter Reviewed-by: Tejun Heo

firewire: optimize iso queueing by setting wake only after the last packet

2011-05-10T20:53:45Z

When queueing iso packets, the run time is dominated by the two MMIO accesses that set the DMA context's wake bit. Because most drivers submit packets in batches, we can save much time by removing all but the last wakeup. The internal kernel API is changed to require a call to fw_iso_context_queue_flush() after a batch of queued packets. The user space API does not change, so one call to FW_CDEV_IOC_QUEUE_ISO must specify multiple packets to take advantage of this optimization. In my measurements, this patch reduces the time needed to queue fifty skip packets from userspace to one sixth on a 2.5 GHz CPU, or to one third at 800 MHz. Signed-off-by: Clemens Ladisch Signed-off-by: Stefan Richter

firewire: octlet AT payloads can be stack-allocated

2011-05-10T20:53:44Z

We do not need slab allocations anymore in order to satisfy streaming DMA mapping constraints, thanks to commit da28947e7e36 "firewire: ohci: avoid separate DMA mapping for small AT payloads". (Besides, the slab-allocated buffers that firewire-core, firewire-sbp2, and firedtv used to provide for 8-byte write and lock requests were still not fully portable since they crossed cacheline boundaries or shared a cacheline with unrelated CPU-accessed data. snd-firewire-lib got this aspect right by using an extra kmalloc/ kfree just for the 8-byte transaction buffer.) This change replaces kmalloc'ed lock transaction scratch buffers in firewire-core, firedtv, and snd-firewire-lib by local stack allocations. Perhaps the most notable result of the change is simpler locking because there is no need to serialize usages of preallocated per-device buffers anymore. Also, allocations and deallocations are simpler. Signed-off-by: Stefan Richter Acked-by: Clemens Ladisch

firewire: core: fix card->reset_jiffies overflow

2011-01-23T11:31:01Z

On a 32-bit machine with, e.g., HZ=1000, jiffies will overflow after about 50 days, so if there are between 25 and 50 days between bus resets, the card->reset_jiffies comparisons can get wrong results. To fix this, ensure that this timestamp always uses 64 bits. Signed-off-by: Clemens Ladisch Signed-off-by: "Stefan Richter"

firewire: cdev: remove unneeded reference

2011-01-23T11:31:01Z

For outbound transactions, the IDR's and the callback's references now have exactly the same lifetime, so we do not need both of them. Signed-off-by: Clemens Ladisch Signed-off-by: "Stefan Richter"

firewire: cdev: always wait for outbound transactions to complete

2011-01-23T11:31:00Z

We must not use fw_cancel_transaction() because it cannot correctly abort still-active transactions. The only place in core-cdev where this matters is when the file is released. Instead of trying to abort the transactions, we wait for them to complete normally, i.e., until all outbound transaction resources have been removed from the IDR tree. Signed-off-by: Clemens Ladisch Signed-off-by: "Stefan Richter"

firewire: cdev: remove unneeded idr_find() from complete_transaction()

2011-01-23T11:31:00Z

Outbound transactions are never aborted with release_client_resource(), so it is not necessary for complete_transaction() to check whether the resource is still registered. Only shutdown_resource() can abort such an transaction, and this is already handled with the in_shutdown check. Signed-off-by: Clemens Ladisch Signed-off-by: "Stefan Richter"

firewire: make PHY packet header format consistent

2010-12-13T19:39:14Z

Change the header of PHY packets to be sent to include a pseudo transaction code. This makes the header consistent with that of received PHY packets, and allows at_context_queue_packet() and log_ar_at_event() to see the packet type directly instead of having to deduce it from the header length or even from the header contents. Signed-off-by: Clemens Ladisch Signed-off-by: Stefan Richter

Merge firewire branches to be released post v2.6.35

2010-08-02T08:09:04Z

Conflicts: drivers/firewire/core-card.c drivers/firewire/core-cdev.c and forgotten #include in drivers/firewire/ohci.c Signed-off-by: Stefan Richter