Manual Reference Pages - BUS_TEARDOWN_INTR (9)
- create, attach and teardown an interrupt handler
device_t dev device_t child struct resource *irq int flags
driver_filter_t *filter driver_intr_t *ithread void *arg
device_t dev struct resource *r int flags
driver_filter_t filter driver_intr_t ithread void *arg
device_t dev device_t child struct resource *irq void *cookiep
bus_teardown_intr device_t dev struct resource *r void *cookiep
will create and attach an interrupt handler to an interrupt
previously allocated by the resource managers
are found in
.In sys/bus.h ,
and give the broad category of interrupt.
also tell the interrupt handlers about certain
device driver characteristics.
marks the handler as being
an exclusive handler for this interrupt.
tells the scheduler that the interrupt handler
is well behaved in a preemptive environment
and does not need
to be protected by the Giant Lock mutex.
marks the interrupt as being a good source of entropy -
this may be used by the entropy device
To define a time-critical handler that will not execute any potentially
blocking operation, use the
section below for information on writing a filter.
Otherwise, use the
The defined handler
will be called with the value
as its only argument.
section below for more information on writing an interrupt handler.
argument is a pointer to a
.Vt void *
will write a cookie for the parent bus use to if it is successful in
establishing an interrupt.
Driver writers may assume that this cookie will be non-zero.
The nexus driver will write 0 on failure to
The interrupt handler will be detached by
The cookie needs to be passed to
in order to tear down the correct interrupt handler.
returns, it is guaranteed that the interrupt function is not active and
will no longer be called.
Mutexes are not allowed to be held across calls to these functions.
A filter runs in primary interrupt context.
In this context, normal mutexes cannot be used.
Only the spin lock version of these can be used (specified by passing
when initializing the mutex).
and similar routines can be called.
Atomic operations from
may be used.
Reads and writes to hardware through
may be used.
PCI configuration registers may be read and written.
All other kernel interfaces cannot be used.
In this restricted environment, care must be taken to account for all
A careful analysis of races should be done as well.
It is generally cheaper to take an extra interrupt, for example, than
to protect variables with spinlocks.
Read, modify, write cycles of hardware registers need to be carefully
analyzed if other threads are accessing the same registers.
Generally, a filter routine will use one of two strategies.
The first strategy is to simply mask the interrupt in hardware and
routine to read the state from the hardware and then reenable
also acknowledges the interrupt before re-enabling the interrupt
source in hardware.
Most PCI hardware can mask its interrupt source.
The second common approach is to use a filter with multiple
In this case, the filter acknowledges the interrupts and queues the
work to the appropriate taskqueue.
Where one has to multiplex different kinds of interrupt sources, like
a network cards transmit and receive paths, this can reduce lock
contention and increase performance.
You should not
from inside a filter.
You may not call anything that uses a normal mutex.
Witness may complain about these.
You can do whatever you want in an ithread routine, except sleep.
Care must be taken not to sleep in an ithread.
In addition, one should minimize lock contention in an ithread routine
because contested locks ripple over to all other ithread routines on
Sleeping is voluntarily giving up control of your thread.
All the sleep routine found in
Waiting for a condition variable described in
Calling any function that does any of these things is sleeping.
Zero is returned on success,
otherwise an appropriate error is returned.
This manual page was written by
.An Jeroen Ruigrok van der Werven
based on the manual pages for
.An Doug Rabson
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