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); |
Table 4–4 describes the arguments that may be passed to M_FLUSH.
Table 4–4 M_FLUSH Arguments and bi_flag values
Flag | |
---|---|
FLUSHR | |
FLUSHW | |
FLUSHRW |
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 Table 4–4. 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.