All modules and drivers are expected to handle the flushing of messages. The user may cause data to be flushed of queued messages from a stream by the submission of an I_FLUSH ioctl(2). Data may be flushed from the read side, write side, or both sides of a stream.
ioctl (fd, I_FLUSH, arg);
Figure 8, Table 8, M_FLUSH Arguments and bi_flag values describes the arguments that may be passed to M_FLUSH.
|
In addition to being able to flush all the data from a queue, a specific band may be flushed using the I_FLUSHBAND ioctl(2).
ioctl (fd, I_FLUSHBAND, bandp);
The ioctl(2) is passed a pointer to a bandinfo structure. The bi_pri field indicates the band priority to be flushed (values from 0 to 255). The bi_flag field indicates the type of flush to do. The legal values for bi_flag are defined in Figure 8, Table 8, M_FLUSH Arguments and bi_flag values. bandinfo has the following format:
struct bandinfo { unsigned char bi_pri; int bi_flag; };
See Flushing Priority Band, which describes M_FLUSHBAND processing, for details on how modules and drivers should handle flush band requests.