| KSTAT_CHAIN_UPDATE(3KSTAT) | Kernel Statistics Library Functions | KSTAT_CHAIN_UPDATE(3KSTAT) |
kstat_chain_update —
#include <kstat.h>
kid_t
kstat_chain_update(kstat_ctl_t
*kc);
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 deletes
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the user's copy of the kstat chain to become out of date.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.
Because of the deletion process, any kstat_t
structures retrieved by the
kstat_lookup(3KSTAT)
function or data pointers obtained through the
kstat_data_lookup(3KSTAT)
function are invalidated by a call to
kstat_chain_update(). New lookup calls must be made
to obtain fresh structures after each chain update.
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.
kstat_chain_update() function will fail if:
| November 29, 2021 | OmniOS |