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/* -*- linux-c -*-
* Print Flush Function
* Copyright (C) 2007-2008 Red Hat Inc.
*
* This file is part of systemtap, and is free software. You can
* redistribute it and/or modify it under the terms of the GNU General
* Public License (GPL); either version 2, or (at your option) any
* later version.
*/
/** Send the print buffer to the transport now.
* Output accumulates in the print buffer until it
* is filled, or this is called. This MUST be called before returning
* from a probe or accumulated output in the print buffer will be lost.
*
* @note Interrupts must be disabled to use this.
*/
static void __stp_print_flush(struct _stp_log *log)
{
char *bufp = log->buf; /* next byte of log->buf left to write */
size_t len = log->len; /* # bytes of log->buf left to write */
const size_t hlen = sizeof(struct _stp_trace);
void *entry = NULL; /* current output buf handle */
size_t bytes_reserved; /* current output buf size available */
/* check to see if there is anything in the buffer */
if (likely(len == 0))
return;
if (unlikely(log->no_flush)) {
log->is_full = true;
return;
}
log->len = 0; /* clear it for later reuse */
dbug_trans(1, "len = %zu\n", len);
/* try to reserve header + len */
bytes_reserved = _stp_data_write_reserve(hlen+len,
&entry);
if (bytes_reserved > 0 && bytes_reserved < hlen){
/* Cannot have header straddle sub buffers. */
/* Pad out that remainder of the subbuf and try again */
memset(entry, 0, bytes_reserved);
bytes_reserved = _stp_data_write_reserve(hlen+len,
&entry);
}
/* require at least header to fit in its entirety */
if (likely(entry && bytes_reserved >= hlen)) {
/* copy new _stp_trace_ header */
struct _stp_trace t = {
.sequence = _stp_seq_inc(),
.pdu_len = len
};
memcpy(&t.magic, STAP_TRACE_MAGIC, 4);
memcpy(_stp_data_entry_data(entry), &t, hlen);
/* copy the first part of the message */
memcpy(_stp_data_entry_data(entry)+hlen,
bufp, bytes_reserved-hlen);
bufp += bytes_reserved-hlen;
len -= bytes_reserved-hlen;
/* send header + first part */
_stp_data_write_commit(entry);
/* loop to copy the rest of the message into subsequent bufs */
while (len > 0) {
bytes_reserved = _stp_data_write_reserve(len, &entry);
if (likely(entry && bytes_reserved)) {
memcpy(_stp_data_entry_data(entry), bufp,
bytes_reserved);
_stp_data_write_commit(entry);
bufp += bytes_reserved;
len -= bytes_reserved;
} else { /* rest of message cannot fit at this time */
/* NB: the receiver must somehow resynch the framing! */
atomic_inc(&_stp_transport_failures);
break;
}
}
} else {
atomic_inc(&_stp_transport_failures);
}
}
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