unix_master(9r) unix_master(9r)
NAME
unix_master - General: Forces execution onto the master CPU
SYNOPSIS
void unix_master(
void );
ARGUMENTS
None
DESCRIPTION
The unix_master routine forces execution of the kernel thread onto the master CPU (also called the boot CPU). In other words, unix_master
binds the kernel thread to the master CPU. To release the kernel thread from the bind to the master CPU, call the unix_release routine. You
can make recursive calls to unix_master as long as you make an equal number of calls to unix_release.
The unix_master routine provides another way besides the simple and complex lock routines to make a kernel module symmetric multiprocessing
(SMP) safe. Although calling unix_master is not optimal for performance on an SMP CPU, it does provide third-party kernel module writers
with an easy way to make their modules SMP safe without using the lock routines.
NOTES
Device drivers should not directly call the unix_master and unix_release routines. One exception to this recommendation is when you want a
device driver's kernel threads to run only on the master CPU. This situation occurs when your driver creates and starts its own kernel
threads and you set the d_funnel member of the associated dsent structure to the value DEV_FUNNEL. In this case, each kernel thread must
call unix_master once to ensure that the kernel thread runs only on the master CPU. Remember to make a corresponding call to unix_release.
CAUTIONS
To avoid deadlock, do not call the unix_master routine under the following circumstances: When holding a simple lock In the driver's inter-
rupt service routine
RETURN VALUES
None
SEE ALSO
routines: unix_release(9r)
unix_master(9r)
