ddi_enter_critical(9f) [opensolaris man page]

ddi_enter_critical(9F)					   Kernel Functions for Drivers 				    ddi_enter_critical(9F)

NAME

       ddi_enter_critical, ddi_exit_critical - enter and exit a critical region of control

SYNOPSIS

       #include <sys/conf.h>
       #include <sys/ddi.h>
       #include <sys/sunddi.h>

       unsigned int ddi_enter_critical(void);

       void ddi_exit_critical(unsignedint ddic);

INTERFACE LEVEL

       Solaris DDI specific (Solaris DDI).

PARAMETERS

       ddic    The returned value from the call to ddi_enter_critical() must be passed to ddi_exit_critical().

DESCRIPTION

       Nearly  all driver operations can be done without any special synchronization and protection mechanisms beyond those provided by, for exam-
       ple, mutexes (see mutex(9F)). However, for certain devices there can exist a very short critical region of code which must  be  allowed	to
       run  uninterrupted. The function ddi_enter_critical() provides a mechanism by which a driver can ask the system to guarantee to the best of
       its ability that the current thread of execution will neither be preempted nor interrupted. This stays in effect until a bracketing call to
       ddi_exit_critical() is made (with an argument which was the returned value from ddi_enter_critical()).

       The  driver  may  not  call  any  functions  external  to  itself  in  between the time it calls ddi_enter_critical() and the time it calls
       ddi_exit_critical().

RETURN VALUES

       The ddi_enter_critical() function returns an opaque unsigned integer which must be used in the subsequent call to ddi_exit_critical().

CONTEXT

       This function can be called from user, interrupt, or kernel context.

WARNINGS

       Driver writers should note that in a multiple processor system  this function does not temporarily suspend other processors from executing.
       This  function  also cannot guarantee to actually block the hardware from doing such things as interrupt acknowledge cycles. What it can do
       is guarantee that the currently executing thread will not be preempted.

       Do not write code  bracketed by ddi_enter_critical() and ddi_exit_critical() that can get caught in an infinite loop, as  the  machine  may
       crash if you do.

SEE ALSO

       mutex(9F)

       Writing Device Drivers

SunOS 5.11							    16 Jan 2006 					    ddi_enter_critical(9F)

proc_signal(9F) 					   Kernel Functions for Drivers 					   proc_signal(9F)

NAME

       proc_signal, proc_ref, proc_unref - send a signal to a process

SYNOPSIS

       #include <sys/ddi.h>
       #include <sys/sunddi.h>
       #include <sys/signal.h>

       void *proc_ref(void)

       voidproc_unref(void *pref);

       int proc_signal(void *pref, int sig);

INTERFACE LEVEL

       Solaris DDI specific (Solaris DDI).

PARAMETERS

       pref    A handle for the process to be signalled.

       sig     Signal number to be sent to the process.

DESCRIPTION

       This  set of routines allows a driver to send a signal to a process. The routine proc_ref() is used to retrieve an unambiguous reference to
       the process for signalling purposes. The return value can be used as a unique handle on the process, even if the process dies. Because sys-
       tem  resources  are  committed to a process reference, proc_unref() should be used to remove it as soon as it is no longer needed.proc_sig-
       nal() is used to send signal sig to the referenced process. The following set of signals may be sent to a process from a driver:

       SIGHUP	   The device has been disconnected.

       SIGINT	   The interrupt character has been received.

       SIGQUIT	   The quit character has been received.

       SIGPOLL	   A pollable event has occurred.

       SIGKILL	   Kill the process (cannot be caught or ignored).

       SIGWINCH    Window size change.

       SIGURG	   Urgent data are available.

       See signal.h(3HEAD) for more details on the meaning of these signals.

       If the process has exited at the time the signal was sent, proc_signal() returns an error code; the caller should remove the  reference	on
       the process by calling proc_unref().

       The driver writer must ensure that for each call made to proc_ref(), there is exactly one corresponding call to proc_unref().

RETURN VALUES

       The proc_ref() returns the following:

       pref    An opaque handle used to refer to the current process.

       The proc_signal() returns the following:

       0     The process existed before the signal was sent.

       -1    The process no longer exists; no signal was sent.

CONTEXT

       The  proc_unref()  and  proc_signal()  functions  can  be called from user, interrupt, or kernel context. The proc_ref() function should be
       called only from user context.

SEE ALSO

       signal.h(3HEAD), putnextctl1(9F)

       Writing Device Drivers

SunOS 5.11							    16 Jan 2006 						   proc_signal(9F)