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systemtap
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runtime
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transport
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Filename :
relayfs.c
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/* -*- linux-c -*- * relayfs.c - relayfs transport functions * * Copyright (C) IBM Corporation, 2005, 2006 * Copyright (C) 2005-2009 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. */ /* This file is only for older kernels that have no debugfs. */ /* relayfs is required! */ #if !defined (CONFIG_RELAYFS_FS) && !defined (CONFIG_RELAYFS_FS_MODULE) #error "RelayFS does not appear to be in this kernel!" #endif #include <linux/kernel.h> #include <linux/module.h> #include <linux/percpu.h> #include <linux/init.h> #include <linux/relayfs_fs.h> #include <linux/namei.h> /* Note: if struct _stp_relay_data_type changes, staplog.c might need * to be changed. */ struct _stp_relay_data_type { struct rchan *rchan; enum _stp_transport_state transport_state; int flushing; }; struct _stp_relay_data_type _stp_relay_data; /* We need to include procfs.c here so that it can see the * _stp_relay_data_type definition. */ #include "procfs.c" /** * __stp_relay_subbuf_start_callback - subbuf_start() relayfs * callback implementation */ static int __stp_relay_subbuf_start_callback(struct rchan_buf *buf, void *subbuf, unsigned prev_subbuf_idx, void *prev_subbuf) { unsigned padding = buf->padding[prev_subbuf_idx]; if (prev_subbuf) *((unsigned *)prev_subbuf) = padding; return sizeof(padding); /* reserve space for padding */ } /** * __stp_relay_buf_full_callback - buf_full() relayfs callback * implementation */ static void __stp_relay_buf_full_callback(struct rchan_buf *buf, unsigned subbuf_idx, void *subbuf) { unsigned padding = buf->padding[subbuf_idx]; *((unsigned *)subbuf) = padding; } static struct rchan_callbacks stp_rchan_callbacks = { .subbuf_start = __stp_relay_subbuf_start_callback, .buf_full = __stp_relay_buf_full_callback, }; static void _stp_transport_data_fs_start(void) { if (_stp_relay_data.transport_state == STP_TRANSPORT_INITIALIZED) _stp_relay_data.transport_state = STP_TRANSPORT_RUNNING; } static void _stp_transport_data_fs_stop(void) { if (_stp_relay_data.transport_state == STP_TRANSPORT_RUNNING) { _stp_relay_data.transport_state = STP_TRANSPORT_STOPPED; _stp_relay_data.flushing = 1; if (_stp_relay_data.rchan) relay_flush(_stp_relay_data.rchan); } } static void _stp_transport_data_fs_close(void) { _stp_transport_data_fs_stop(); if (_stp_relay_data.rchan) { relay_close(_stp_relay_data.rchan); _stp_relay_data.rchan = NULL; } } static int _stp_transport_data_fs_init(void) { int rc = 0; int i; dbug_trans(1, "relay_open %d %d\n", _stp_subbuf_size, _stp_nsubbufs); _stp_relay_data.transport_state = STP_TRANSPORT_STOPPED; _stp_relay_data.flushing = 0; /* Create "trace" file. */ _stp_relay_data.rchan = relay_open("trace", _stp_get_module_dir(), _stp_subbuf_size, _stp_nsubbufs, 0, &stp_rchan_callbacks); if (!_stp_relay_data.rchan) { rc = -ENOENT; goto err; } { u64 relay_mem; relay_mem = _stp_subbuf_size * _stp_nsubbufs; #ifdef STP_BULKMODE relay_mem *= num_online_cpus(); #endif _stp_allocated_net_memory += relay_mem; _stp_allocated_memory += relay_mem; } /* now set ownership */ for_each_online_cpu(i) { _stp_relay_data.rchan->buf[i]->dentry->d_inode->i_uid = _stp_uid; _stp_relay_data.rchan->buf[i]->dentry->d_inode->i_gid = _stp_gid; } /* We're initialized. */ _stp_relay_data.transport_state = STP_TRANSPORT_INITIALIZED; return rc; err: errk("couldn't create relay channel.\n"); _stp_transport_data_fs_close(); return rc; } static enum _stp_transport_state _stp_transport_get_state(void) { return _stp_relay_data.transport_state; } static void _stp_transport_data_fs_overwrite(int overwrite) { _stp_relay_data.rchan->overwrite = overwrite; } /** * _stp_data_write_reserve - try to reserve size_request bytes * @size_request: number of bytes to attempt to reserve * @entry: entry is returned here * * Returns number of bytes reserved, 0 if full. On return, entry * will point to allocated opaque pointer. Use * _stp_data_entry_data() to get pointer to copy data into. * * (For this code's purposes, entry is filled in with the actual * data pointer, but the caller doesn't know that.) */ static size_t _stp_data_write_reserve(size_t size_request, void **entry) { if (entry == NULL) return -EINVAL; *entry = relay_reserve(_stp_relay_data.rchan, size_request); if (*entry == NULL) return 0; return size_request; } static unsigned char *_stp_data_entry_data(void *entry) { /* Nothing to do here. */ return entry; } static int _stp_data_write_commit(void *entry) { /* Nothing to do here. */ return 0; }