Catch up to the new swi API.
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John Baldwin
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.\" Copyright (c) 2000 John H. Baldwin
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.\" Copyright (c) 2000-2001 John H. Baldwin <jhb@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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@ -28,68 +28,68 @@
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.Dt SWI 9
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.Os
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.Sh NAME
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.Nm sched_swi ,
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.Nm sinthand_add
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.Nm swi_add ,
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.Nm swi_sched
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.Nd register and schedule software interrupt handlers
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.Sh SYNOPSIS
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.Fd #include <sys/param.h>
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.Fd #include <sys/bus.h>
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.Fd #include <sys/proc.h>
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.Fd #include <sys/interrupt.h>
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.Vt "extern struct ithd *tty_ithd" ;
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.Vt "extern struct ithd *clk_ithd" ;
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.Vt "extern struct intrhand *net_ih" ;
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.Vt "extern struct intrhand *softclock_ih" ;
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.Vt "extern struct intrhand *vm_ih" ;
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.Ft void
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.Fn sched_swi "struct intrhand *handler" "int flags"
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.Ft struct intrhand *
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.Fo sinthand_add
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.Vt "extern void *net_ih" ;
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.Vt "extern void *softclock_ih" ;
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.Vt "extern void *vm_ih" ;
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.Ft int
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.Fo swi_add
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.Fa "struct ithd **ithdp"
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.Fa "const char *name"
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.Fa "struct ithd **thread"
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.Fa "driver_intr_t handler"
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.Fa "void *arg"
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.Fa "int pri"
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.Fa "int flags"
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.Fa "enum intr_type flags"
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.Fa "void **cookiep"
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.Fc
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.Ft void
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.Fn swi_sched "void *handler" "int flags"
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.Sh DESCRIPTION
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These functions are used to register and schedule software interrupt handlers.
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Software interrupt handlers are attached to a software interrupt thread, just
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as hardware interrupt handlers are attached to a hardware interrupt thread.
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This means that multiple handlers can be attached to the same thread.
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Multiple handlers can be attached to the same thread.
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Software interrupt handlers can be used to queue up less critical processing
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inside of hardware interrupt handlers so that the work can be done at a later
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time.
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Software interrupt threads are different from other kernel threads in that they
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are treated as an interrupt thread.
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This means that time spent executing these threads is counted as interrupt
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time, and that they can be run via a lightweight context switch during
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.Fn ast .
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time, and that they can be run via a lightweight context switch.
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.Pp
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The
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.Fn sinthand_add
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.Fn swi_add
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function is used to register a new software interrupt handler.
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The
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.Fa name
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argument is used to associate a name with a specific handler.
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This name is appended to the name of the software interrupt thread that this
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handler is attached to.
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The
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.Fa thread
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.Fa ithdp
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argument is an optional pointer to a
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.Li struct ithd
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pointer.
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If this argument points to an existing software interrupt thread, then this
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handler will be attached to that thread.
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Otherwise a new thread will be created, and if
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.Fa thread
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.Fa ithdp
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is not
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.Dv NULL ,
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then the pointer at that address to will be modified to point to the
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newly created thread.
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The
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.Fa name
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argument is used to associate a name with a specific handler.
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This name is appended to the name of the software interrupt thread that this
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handler is attached to.
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The
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.Fa handler
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is the function that will be called when the handler is scheduled to run.
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argument is the function that will be executed when the handler is scheduled
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to run.
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The
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.Fa arg
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parameter will be passed in as the only parameter to
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@ -97,22 +97,27 @@ parameter will be passed in as the only parameter to
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when the function is executed.
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The
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.Fa pri
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value specifies the priority to assign to an interrupt thread if one is created,
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value specifies the priority of this interrupt handler relative to other
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software interrupt handlers.
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If an interrupt thread is created, then this value is used as the vector,
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and the
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.Fa flags
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argument is used to specify the attributes of a handler such as
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.Dv INTR_MPSAFE .
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.Fn sinthand_add
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returns a pointer to a
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.Li struct intrhand
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which is used later to schedule the handler to run.
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The
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.Fn cookiep
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argument points to a
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.Li void *
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cookie.
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This cookie will be set to a value that uniquely identifies this handler,
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and is used to schedule the handler for execution later on.
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.Pp
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The
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.Fn sched_swi
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.Fn swi_sched
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function is used to schedule an interrupt handler and its associated thread to
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run.
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The
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.Fa handler
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.Fa cookie
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argument specifies which software interrupt handler should be scheduled to run.
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The
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.Fa flags
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@ -164,40 +169,67 @@ handler cookies are used to schedule software interrupt threads to run for the
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networking stack, clock interrupt, and VM subsystem respectively.
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.Sh RETURN VALUES
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The
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.Fn sinthand_add
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function returns a pointer to the newly created
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.Li struct intrhand
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if successful or
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.Dv NULL
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on error.
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.Fn swi_add
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function returns zero on success and non-zero on failure.
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.Sh ERRORS
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The
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.Fn swi_add
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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The system-imposed limit on the total
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number of processes under execution would be exceeded.
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The limit is given by the
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.Xr sysctl 3
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MIB variable
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.Dv KERN_MAXPROC .
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.It Bq Er EINVAL
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The
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.Fa flags
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argument specifies either
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.Dv INTR_ENTROPY
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or
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.Dv INTR_FAST .
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.It Bq Er EINVAL
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The
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.Fa ithdp
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argument points to a hardware interrupt thread.
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.It Bq Er EINVAL
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Either of the
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.Fa name
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or
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.Fa handler
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arguments are
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.Dv NULL .
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.It Bq Er EINVAL
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The
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.Dv INTR_EXCL
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flag is specified and the interrupt thread pointed to by
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.Fa ithdp
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already has at least one handler, or the interrupt thread already has an
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exclusive handler.
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.El
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.Sh SEE ALSO
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.Xr ithread 9 ,
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.Xr taskqueue 9
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.Sh HISTORY
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The
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.Fn sinthand_add
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and the
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.Fn sched_swi
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.Fn swi_add
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and
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.Fn swi_sched
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functions first appeared in
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.Fx 5.0 .
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They replaced the
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.Fn register_swi
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function which appeared in
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.Fx 3.0
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and the
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.Fn setsoft* ,
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and
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.Fn schedsoft*
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functions which date back to at least
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.Bx 4.4 .
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.Sh BUGS
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The
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.Fn sinthand_add
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function currently doesn't check for or allow for the
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.Dv INTR_EXCL
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flag to be used to allow a software interrupt handler to have exclusive
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access to a particular software interrupt thread.
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There is also no checking to verify that one does not add a software interrupt
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handler to a hardware interrupt thread.
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.Pp
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The
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.Fn sinthand_add
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function should really return an error code and use a
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.Fa "void **cookiep"
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argument to return a cookie that is passed in as the first argument to
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.Fn sched_swi
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instead of exposing the
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.Li struct intrhand
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type.
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.Pp
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Most of the global variables described in this manual page should not be
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global, or at the very least should not be declared in
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