The interfaces to control kernel tracing and process filtering are used only with kernel handles, handles created by tnfctl_kernel_open(3TNF). These interfaces are used to change the tracing and filter states for kernel tracing.

tnfctl_trace_state_set() sets the kernel global tracing state to "on" if trace_state is B_TRUE, or to "off" if trace_state is B_FALSE. For the kernel, trace_state is off by default. Probes that are enabled will not write out data unless this state is on. Use tnfctl_trace_attrs_get(3TNF) to retrieve the current tracing state.

tnfctl_filter_state_set() sets the kernel process filtering state to "on" if filter_state is B_TRUE, or to "off" if filter_state is B_FALSE. filter_state is off by default. If it is on, only probe points encountered by processes in the process filter set by tnfctl_filter_list_add() will generate trace points. Use tnfctl_trace_attrs_get(3TNF) to retrieve the current process filtering state.

tnfctl_filter_list_get() returns the process filter list as an array in pid_list. The count of elements in the process filter list is returned in pid_count. The caller should use free(3C) to free memory allocated for the array pid_list.

tnfctl_filter_list_add() adds pid_to_add to the process filter list. The process filter list is maintained even when the process filtering state is off, but it has no effect unless the process filtering state is on.

tnfctl_filter_list_delete() deletes pid_to_delete from the process filter list. It returns an error if the process does not exist or is not in the filter list.

The interfaces tnfctl_trace_state_set(), tnfctl_filter_state_set(), tnfctl_filter_list_add(), tnfctl_filter_list_delete(), and tnfctl_filter_list_get() return TNFCTL_ERR_NONE upon success.

The following error codes apply to tnfctl_trace_state_set:

TNFCTL_ERR_BADARG

The handle is not a kernel handle.

TNFCTL_ERR_NOBUF

Cannot turn on tracing without a buffer being allocated.

TNFCTL_ERR_BUFBROKEN

Tracing is broken in the target.

TNFCTL_ERR_INTERNAL

An internal error occurred.

The following error codes apply to tnfctl_filter_state_set:

TNFCTL_ERR_BADARG

The handle is not a kernel handle.

TNFCTL_ERR_INTERNAL

An internal error occurred.

The following error codes apply to tnfctl_filter_list_add:

TNFCTL_ERR_BADARG

The handle is not a kernel handle.

TNFCTL_ERR_NOPROCESS

No such process exists.

TNFCTL_ERR_ALLOCFAIL

A memory allocation failure occurred.

TNFCTL_ERR_INTERNAL

An internal error occurred.

The following error codes apply to tnfctl_filter_list_delete:

TNFCTL_ERR_BADARG

The handle is not a kernel handle.

TNFCTL_ERR_NOPROCESS

No such process exists.

TNFCTL_ERR_INTERNAL

An internal error occurred.

The following error codes apply to tnfctl_filter_list_get:

TNFCTL_ERR_BADARG

The handle is not a kernel handle.

TNFCTL_ERR_ALLOCFAIL

A memory allocation failure occurred.

TNFCTL_ERR_INTERNAL

An internal error occurred.

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

prex(1), TNF_PROBE(3TNF), free(3C), libtnfctl(3TNF), tnfctl_kernel_open(3TNF), tnfctl_trace_attrs_get (3TNF), tracing(3TNF), tnf_kernel_probes(4), attributes(5)