firewire: core: use non-reentrant workqueue with rescuer
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 <stefanr@s5r6.in-berlin.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
diff --git a/drivers/firewire/core-transaction.c b/drivers/firewire/core-transaction.c
index 77275fd..d4c28a2 100644
--- a/drivers/firewire/core-transaction.c
+++ b/drivers/firewire/core-transaction.c
@@ -36,6 +36,7 @@
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/types.h>
+#include <linux/workqueue.h>
#include <asm/byteorder.h>
@@ -1213,13 +1214,21 @@
{
int ret;
+ fw_wq = alloc_workqueue(KBUILD_MODNAME,
+ WQ_NON_REENTRANT | WQ_MEM_RECLAIM, 0);
+ if (!fw_wq)
+ return -ENOMEM;
+
ret = bus_register(&fw_bus_type);
- if (ret < 0)
+ if (ret < 0) {
+ destroy_workqueue(fw_wq);
return ret;
+ }
fw_cdev_major = register_chrdev(0, "firewire", &fw_device_ops);
if (fw_cdev_major < 0) {
bus_unregister(&fw_bus_type);
+ destroy_workqueue(fw_wq);
return fw_cdev_major;
}
@@ -1235,6 +1244,7 @@
{
unregister_chrdev(fw_cdev_major, "firewire");
bus_unregister(&fw_bus_type);
+ destroy_workqueue(fw_wq);
idr_destroy(&fw_device_idr);
}