/usr/share/systemtap/runtime/print_flush.c is in systemtap-common 1.6-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 | /* -*- 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 Preemption must be disabled to use this.
*/
#ifdef CONFIG_PREEMPT_RT
static DEFINE_RAW_SPINLOCK(_stp_print_lock);
#else
static DEFINE_SPINLOCK(_stp_print_lock);
#endif
void EXPORT_FN(stp_print_flush)(_stp_pbuf *pb)
{
size_t len = pb->len;
void *entry = NULL;
/* check to see if there is anything in the buffer */
dbug_trans(1, "len = %zu\n", len);
if (likely(len == 0))
return;
pb->len = 0;
if (unlikely(_stp_transport_get_state() != STP_TRANSPORT_RUNNING))
return;
#ifdef STP_BULKMODE
#ifdef NO_PERCPU_HEADERS
{
char *bufp = pb->buf;
while (len > 0) {
size_t bytes_reserved;
bytes_reserved = _stp_data_write_reserve(len, &entry);
if (likely(entry && bytes_reserved > 0)) {
memcpy(_stp_data_entry_data(entry), bufp,
bytes_reserved);
_stp_data_write_commit(entry);
bufp += bytes_reserved;
len -= bytes_reserved;
}
else {
atomic_inc(&_stp_transport_failures);
break;
}
}
}
#else /* !NO_PERCPU_HEADERS */
{
char *bufp = pb->buf;
struct _stp_trace t = { .sequence = _stp_seq_inc(),
.pdu_len = len};
size_t bytes_reserved;
bytes_reserved = _stp_data_write_reserve(sizeof(struct _stp_trace), &entry);
if (likely(entry && bytes_reserved > 0)) {
/* prevent unaligned access by using memcpy() */
memcpy(_stp_data_entry_data(entry), &t, sizeof(t));
_stp_data_write_commit(entry);
}
else {
atomic_inc(&_stp_transport_failures);
return;
}
while (len > 0) {
bytes_reserved = _stp_data_write_reserve(len, &entry);
if (likely(entry && bytes_reserved > 0)) {
memcpy(_stp_data_entry_data(entry), bufp,
bytes_reserved);
_stp_data_write_commit(entry);
bufp += bytes_reserved;
len -= bytes_reserved;
}
else {
atomic_inc(&_stp_transport_failures);
break;
}
}
}
#endif /* !NO_PERCPU_HEADERS */
#else /* !STP_BULKMODE */
#if STP_TRANSPORT_VERSION == 1
/** STP_TRANSPORT_VERSION == 1 is special, _stp_ctl_write will
pass through procfs _stp_ctl_write_fs which recognizes
STP_REALTIME_DATA as data that needs to be send right away
over the .cmd channel instead of being queued. */
if (unlikely(_stp_ctl_write(STP_REALTIME_DATA, pb->buf, len) <= 0))
atomic_inc (&_stp_transport_failures);
#else /* STP_TRANSPORT_VERSION != 1 */
{
unsigned long flags;
char *bufp = pb->buf;
dbug_trans(1, "calling _stp_data_write...\n");
spin_lock_irqsave(&_stp_print_lock, flags);
while (len > 0) {
size_t bytes_reserved;
bytes_reserved = _stp_data_write_reserve(len, &entry);
if (likely(entry && bytes_reserved > 0)) {
memcpy(_stp_data_entry_data(entry), bufp,
bytes_reserved);
_stp_data_write_commit(entry);
bufp += bytes_reserved;
len -= bytes_reserved;
}
else {
atomic_inc(&_stp_transport_failures);
break;
}
}
spin_unlock_irqrestore(&_stp_print_lock, flags);
}
#endif /* STP_TRANSPORT_VERSION != 1 */
#endif /* !STP_BULKMODE */
}
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