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kstat_chain_update

Section: Kernel Statistics Library Functions (3KSTAT)
Updated: 3 Aug 2004
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NAME

kstat_chain_update - update the kstat header chain  

SYNOPSIS

cc [ flag... ] file... -lkstat [ library...]
#include <kstat.h>

kid_t kstat_chain_update(kstat_ctl_t *kc);  

DESCRIPTION

The kstat_chain_update() function brings the user's kstat header chain in sync with that of the kernel. The kstat chain is a linked list of kstat headers (kstat_t's) pointed to by kc->kc_chain, which is initialized by kstat_open(3KSTAT). This chain constitutes a list of all kstats currently in the system.

During normal operation, the kernel creates new kstats and delete old ones as various device instances are added and removed, thereby causing the user's copy of the kstat chain to become out of date. The kstat_chain_update() function detects this condition by comparing the kernel's current kstat chain ID (KCID), which is incremented every time the kstat chain changes, to the user's KCID, kc->kc_chain_id. If the KCIDs match, kstat_chain_update() does nothing. Otherwise, it deletes any invalid kstat headers from the user's kstat chain, adds any new ones, and sets kc->kc_chain_id to the new KCID. All other kstat headers in the user's kstat chain are unmodified.  

RETURN VALUES

Upon successful completion, kstat_chain_update() returns the new KCID if the kstat chain has changed and 0 if it has not changed. Otherwise, it returns -1 and sets errno to indicate the error.  

ERRORS

The kstat_chain_update() function will fail if:

EAGAIN The kstat was temporarily unavailable for reading or writing.

ENOMEM Insufficient storage space is available.

ENXIO The given kstat could not be located for reading.

EOVERFLOW The data for the given kstat was too large to be stored in the structure.

 

FILES

/dev/kstat kernel statistics driver

 

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPEATTRIBUTE VALUE
Interface StabilityStable
MT-LevelUnsafe

 

SEE ALSO

kstat(3KSTAT), kstat_lookup(3KSTAT), kstat_open(3KSTAT), kstat_read(3KSTAT), attributes(5)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUES
ERRORS
FILES
ATTRIBUTES
SEE ALSO

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Time: 02:38:31 GMT, October 02, 2010