curproc(9) - NetBSD Manual Pages

CURPROC(9)             NetBSD Kernel Developer's Manual             CURPROC(9)


NAME

     curcpu, curlwp, curproc -- current processor, thread, and process


SYNOPSIS

     #include <sys/proc.h>

     struct cpu_info *
     curcpu(void);

     struct proc *curproc;
     struct lwp *curlwp;

     #include <sys/cpu.h>

     bool
     curcpu_stable(void);


DESCRIPTION

     The following retrieve the current CPU, process, and thread (lightweight
     process, or LWP), respectively:

     curcpu()      Returns a pointer to the struct cpu_info structure repre-
                   senting the CPU that the code calling it is running on.

                   The value of curcpu() is unstable and may be stale as soon
                   as it is read unless the caller prevents preemption by
                   raising the IPL (spl(9), mutex(9)), by disabling preemption
                   (kpreempt_disable(9)), or by binding the thread to its CPU
                   (curlwp_bind(9)).

                   The function curcpu_stable() can be used in assertions
                   (KASSERT(9)) to verify that curcpu() is stable in the cur-
                   rent context.  curcpu_stable() MUST NOT be used to make
                   dynamic decisions about whether to query curcpu().

     curproc       Yields a pointer to the struct proc structure representing
                   the currently running process.

                   The value of curproc is stable and does not change during
                   execution except in machine-dependent logic to perform con-
                   text switches, so it works like a global constant, not like
                   a stateful procedure.

     curlwp        Yields a pointer to the struct lwp structure representing
                   the currently running thread.

                   The value of curlwp is stable and does not change during
                   execution except in machine-dependent logic to perform con-
                   text switches, so it works like a global constant, not like
                   a stateful procedure.


SOURCE REFERENCES

     The curcpu() macro is defined in the machine-independent machine/cpu.h.

     The curproc macro is defined in sys/lwp.h.

     The curlwp macro has a machine-independent definition in sys/lwp.h, but
     it may be overridden by machine/cpu.h, and must be overridden on archi-
     tectures supporting multiprocessing and kernel preemption.

     The curcpu_stable() function is defined in kern/subr_cpu.c.


SEE ALSO

     cpu_number(9), proc_find(9)

NetBSD 10.99                     July 8, 2023                     NetBSD 10.99