freebsd-dev/sys/dev/tcp_log/tcp_log_dev.c
Warner Losh 52467047aa Regularize the Netflix copyright
Use recent best practices for Copyright form at the top of
the license:
1. Remove all the All Rights Reserved clauses on our stuff. Where we
   piggybacked others, use a separate line to make things clear.
2. Use "Netflix, Inc." everywhere.
3. Use a single line for the copyright for grep friendliness.
4. Use date ranges in all places for our stuff.

Approved by: Netflix Legal (who gave me the form), adrian@ (pmc files)
2019-02-04 21:28:25 +00:00

521 lines
14 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2016-2017 Netflix, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/filio.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/poll.h>
#include <sys/queue.h>
#include <sys/refcount.h>
#include <sys/mutex.h>
#include <sys/selinfo.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <sys/tree.h>
#include <sys/uio.h>
#include <machine/atomic.h>
#include <sys/counter.h>
#include <dev/tcp_log/tcp_log_dev.h>
#ifdef TCPLOG_DEBUG_COUNTERS
extern counter_u64_t tcp_log_que_read;
extern counter_u64_t tcp_log_que_freed;
#endif
static struct cdev *tcp_log_dev;
static struct selinfo tcp_log_sel;
static struct log_queueh tcp_log_dev_queue_head = STAILQ_HEAD_INITIALIZER(tcp_log_dev_queue_head);
static struct log_infoh tcp_log_dev_reader_head = STAILQ_HEAD_INITIALIZER(tcp_log_dev_reader_head);
MALLOC_DEFINE(M_TCPLOGDEV, "tcp_log_dev", "TCP log device data structures");
static int tcp_log_dev_listeners = 0;
static struct mtx tcp_log_dev_queue_lock;
#define TCP_LOG_DEV_QUEUE_LOCK() mtx_lock(&tcp_log_dev_queue_lock)
#define TCP_LOG_DEV_QUEUE_UNLOCK() mtx_unlock(&tcp_log_dev_queue_lock)
#define TCP_LOG_DEV_QUEUE_LOCK_ASSERT() mtx_assert(&tcp_log_dev_queue_lock, MA_OWNED)
#define TCP_LOG_DEV_QUEUE_UNLOCK_ASSERT() mtx_assert(&tcp_log_dev_queue_lock, MA_NOTOWNED)
#define TCP_LOG_DEV_QUEUE_REF(tldq) refcount_acquire(&((tldq)->tldq_refcnt))
#define TCP_LOG_DEV_QUEUE_UNREF(tldq) refcount_release(&((tldq)->tldq_refcnt))
static void tcp_log_dev_clear_refcount(struct tcp_log_dev_queue *entry);
static void tcp_log_dev_clear_cdevpriv(void *data);
static int tcp_log_dev_open(struct cdev *dev __unused, int flags,
int devtype __unused, struct thread *td __unused);
static int tcp_log_dev_write(struct cdev *dev __unused,
struct uio *uio __unused, int flags __unused);
static int tcp_log_dev_read(struct cdev *dev __unused, struct uio *uio,
int flags __unused);
static int tcp_log_dev_ioctl(struct cdev *dev __unused, u_long cmd,
caddr_t data, int fflag __unused, struct thread *td __unused);
static int tcp_log_dev_poll(struct cdev *dev __unused, int events,
struct thread *td);
enum tcp_log_dev_queue_lock_state {
QUEUE_UNLOCKED = 0,
QUEUE_LOCKED,
};
static struct cdevsw tcp_log_cdevsw = {
.d_version = D_VERSION,
.d_read = tcp_log_dev_read,
.d_open = tcp_log_dev_open,
.d_write = tcp_log_dev_write,
.d_poll = tcp_log_dev_poll,
.d_ioctl = tcp_log_dev_ioctl,
#ifdef NOTYET
.d_mmap = tcp_log_dev_mmap,
#endif
.d_name = "tcp_log",
};
static __inline void
tcp_log_dev_queue_validate_lock(int lockstate)
{
#ifdef INVARIANTS
switch (lockstate) {
case QUEUE_LOCKED:
TCP_LOG_DEV_QUEUE_LOCK_ASSERT();
break;
case QUEUE_UNLOCKED:
TCP_LOG_DEV_QUEUE_UNLOCK_ASSERT();
break;
default:
kassert_panic("%s:%d: unknown queue lock state", __func__,
__LINE__);
}
#endif
}
/*
* Clear the refcount. If appropriate, it will remove the entry from the
* queue and call the destructor.
*
* This must be called with the queue lock held.
*/
static void
tcp_log_dev_clear_refcount(struct tcp_log_dev_queue *entry)
{
KASSERT(entry != NULL, ("%s: called with NULL entry", __func__));
TCP_LOG_DEV_QUEUE_LOCK_ASSERT();
if (TCP_LOG_DEV_QUEUE_UNREF(entry)) {
#ifdef TCPLOG_DEBUG_COUNTERS
counter_u64_add(tcp_log_que_freed, 1);
#endif
/* Remove the entry from the queue and call the destructor. */
STAILQ_REMOVE(&tcp_log_dev_queue_head, entry, tcp_log_dev_queue,
tldq_queue);
(*entry->tldq_dtor)(entry);
}
}
static void
tcp_log_dev_clear_cdevpriv(void *data)
{
struct tcp_log_dev_info *priv;
struct tcp_log_dev_queue *entry, *entry_tmp;
priv = (struct tcp_log_dev_info *)data;
if (priv == NULL)
return;
/*
* Lock the queue and drop our references. We hold references to all
* the entries starting with tldi_head (or, if tldi_head == NULL, all
* entries in the queue).
*
* Because we don't want anyone adding addition things to the queue
* while we are doing this, we lock the queue.
*/
TCP_LOG_DEV_QUEUE_LOCK();
if (priv->tldi_head != NULL) {
entry = priv->tldi_head;
STAILQ_FOREACH_FROM_SAFE(entry, &tcp_log_dev_queue_head,
tldq_queue, entry_tmp) {
tcp_log_dev_clear_refcount(entry);
}
}
tcp_log_dev_listeners--;
KASSERT(tcp_log_dev_listeners >= 0,
("%s: tcp_log_dev_listeners is unexpectedly negative", __func__));
STAILQ_REMOVE(&tcp_log_dev_reader_head, priv, tcp_log_dev_info,
tldi_list);
TCP_LOG_DEV_QUEUE_LOCK_ASSERT();
TCP_LOG_DEV_QUEUE_UNLOCK();
free(priv, M_TCPLOGDEV);
}
static int
tcp_log_dev_open(struct cdev *dev __unused, int flags, int devtype __unused,
struct thread *td __unused)
{
struct tcp_log_dev_info *priv;
struct tcp_log_dev_queue *entry;
int rv;
/*
* Ideally, we shouldn't see these because of file system
* permissions.
*/
if (flags & (FWRITE | FEXEC | FAPPEND | O_TRUNC))
return (ENODEV);
/* Allocate space to hold information about where we are. */
priv = malloc(sizeof(struct tcp_log_dev_info), M_TCPLOGDEV,
M_ZERO | M_WAITOK);
/* Stash the private data away. */
rv = devfs_set_cdevpriv((void *)priv, tcp_log_dev_clear_cdevpriv);
if (!rv) {
/*
* Increase the listener count, add this reader to the list, and
* take references on all current queues.
*/
TCP_LOG_DEV_QUEUE_LOCK();
tcp_log_dev_listeners++;
STAILQ_INSERT_HEAD(&tcp_log_dev_reader_head, priv, tldi_list);
priv->tldi_head = STAILQ_FIRST(&tcp_log_dev_queue_head);
if (priv->tldi_head != NULL)
priv->tldi_cur = priv->tldi_head->tldq_buf;
STAILQ_FOREACH(entry, &tcp_log_dev_queue_head, tldq_queue)
TCP_LOG_DEV_QUEUE_REF(entry);
TCP_LOG_DEV_QUEUE_UNLOCK();
} else {
/* Free the entry. */
free(priv, M_TCPLOGDEV);
}
return (rv);
}
static int
tcp_log_dev_write(struct cdev *dev __unused, struct uio *uio __unused,
int flags __unused)
{
return (ENODEV);
}
static __inline void
tcp_log_dev_rotate_bufs(struct tcp_log_dev_info *priv, int *lockstate)
{
struct tcp_log_dev_queue *entry;
KASSERT(priv->tldi_head != NULL,
("%s:%d: priv->tldi_head unexpectedly NULL",
__func__, __LINE__));
KASSERT(priv->tldi_head->tldq_buf == priv->tldi_cur,
("%s:%d: buffer mismatch (%p vs %p)",
__func__, __LINE__, priv->tldi_head->tldq_buf,
priv->tldi_cur));
tcp_log_dev_queue_validate_lock(*lockstate);
if (*lockstate == QUEUE_UNLOCKED) {
TCP_LOG_DEV_QUEUE_LOCK();
*lockstate = QUEUE_LOCKED;
}
entry = priv->tldi_head;
priv->tldi_head = STAILQ_NEXT(entry, tldq_queue);
tcp_log_dev_clear_refcount(entry);
priv->tldi_cur = NULL;
}
static int
tcp_log_dev_read(struct cdev *dev __unused, struct uio *uio, int flags)
{
struct tcp_log_common_header *buf;
struct tcp_log_dev_info *priv;
struct tcp_log_dev_queue *entry;
ssize_t len;
int lockstate, rv;
/* Get our private info. */
rv = devfs_get_cdevpriv((void **)&priv);
if (rv)
return (rv);
lockstate = QUEUE_UNLOCKED;
/* Do we need to get a new buffer? */
while (priv->tldi_cur == NULL ||
priv->tldi_cur->tlch_length <= priv->tldi_off) {
/* Did we somehow forget to rotate? */
KASSERT(priv->tldi_cur == NULL,
("%s:%d: tldi_cur is unexpectedly non-NULL", __func__,
__LINE__));
if (priv->tldi_cur != NULL)
tcp_log_dev_rotate_bufs(priv, &lockstate);
/*
* Before we start looking at tldi_head, we need a lock on the
* queue to make sure tldi_head stays stable.
*/
if (lockstate == QUEUE_UNLOCKED) {
TCP_LOG_DEV_QUEUE_LOCK();
lockstate = QUEUE_LOCKED;
}
/* We need the next buffer. Do we have one? */
if (priv->tldi_head == NULL && (flags & FNONBLOCK)) {
rv = EAGAIN;
goto done;
}
if (priv->tldi_head == NULL) {
/* Sleep and wait for more things we can read. */
rv = mtx_sleep(&tcp_log_dev_listeners,
&tcp_log_dev_queue_lock, PCATCH, "tcplogdev", 0);
if (rv)
goto done;
if (priv->tldi_head == NULL)
continue;
}
/*
* We have an entry to read. We want to try to create a
* buffer, if one doesn't already exist.
*/
entry = priv->tldi_head;
if (entry->tldq_buf == NULL) {
TCP_LOG_DEV_QUEUE_LOCK_ASSERT();
buf = (*entry->tldq_xform)(entry);
if (buf == NULL) {
rv = EBUSY;
goto done;
}
entry->tldq_buf = buf;
}
priv->tldi_cur = entry->tldq_buf;
priv->tldi_off = 0;
}
/* Copy what we can from this buffer to the output buffer. */
if (uio->uio_resid > 0) {
/* Drop locks so we can take page faults. */
if (lockstate == QUEUE_LOCKED)
TCP_LOG_DEV_QUEUE_UNLOCK();
lockstate = QUEUE_UNLOCKED;
KASSERT(priv->tldi_cur != NULL,
("%s: priv->tldi_cur is unexpectedly NULL", __func__));
/* Copy as much as we can to this uio. */
len = priv->tldi_cur->tlch_length - priv->tldi_off;
if (len > uio->uio_resid)
len = uio->uio_resid;
rv = uiomove(((uint8_t *)priv->tldi_cur) + priv->tldi_off,
len, uio);
if (rv != 0)
goto done;
priv->tldi_off += len;
#ifdef TCPLOG_DEBUG_COUNTERS
counter_u64_add(tcp_log_que_read, len);
#endif
}
/* Are we done with this buffer? If so, find the next one. */
if (priv->tldi_off >= priv->tldi_cur->tlch_length) {
KASSERT(priv->tldi_off == priv->tldi_cur->tlch_length,
("%s: offset (%ju) exceeds length (%ju)", __func__,
(uintmax_t)priv->tldi_off,
(uintmax_t)priv->tldi_cur->tlch_length));
tcp_log_dev_rotate_bufs(priv, &lockstate);
}
done:
tcp_log_dev_queue_validate_lock(lockstate);
if (lockstate == QUEUE_LOCKED)
TCP_LOG_DEV_QUEUE_UNLOCK();
return (rv);
}
static int
tcp_log_dev_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data,
int fflag __unused, struct thread *td __unused)
{
struct tcp_log_dev_info *priv;
int rv;
/* Get our private info. */
rv = devfs_get_cdevpriv((void **)&priv);
if (rv)
return (rv);
/*
* Set things. Here, we are most concerned about the non-blocking I/O
* flag.
*/
rv = 0;
switch (cmd) {
case FIONBIO:
break;
case FIOASYNC:
if (*(int *)data != 0)
rv = EINVAL;
break;
default:
rv = ENOIOCTL;
}
return (rv);
}
static int
tcp_log_dev_poll(struct cdev *dev __unused, int events, struct thread *td)
{
struct tcp_log_dev_info *priv;
int revents;
/*
* Get our private info. If this fails, claim that all events are
* ready. That should prod the user to do something that will
* make the error evident to them.
*/
if (devfs_get_cdevpriv((void **)&priv))
return (events);
revents = 0;
if (events & (POLLIN | POLLRDNORM)) {
/*
* We can (probably) read right now if we are partway through
* a buffer or if we are just about to start a buffer.
* Because we are going to read tldi_head, we should acquire
* a read lock on the queue.
*/
TCP_LOG_DEV_QUEUE_LOCK();
if ((priv->tldi_head != NULL && priv->tldi_cur == NULL) ||
(priv->tldi_cur != NULL &&
priv->tldi_off < priv->tldi_cur->tlch_length))
revents = events & (POLLIN | POLLRDNORM);
else
selrecord(td, &tcp_log_sel);
TCP_LOG_DEV_QUEUE_UNLOCK();
} else {
/*
* It only makes sense to poll for reading. So, again, prod the
* user to do something that will make the error of their ways
* apparent.
*/
revents = events;
}
return (revents);
}
int
tcp_log_dev_add_log(struct tcp_log_dev_queue *entry)
{
struct tcp_log_dev_info *priv;
int rv;
bool wakeup_needed;
KASSERT(entry->tldq_buf != NULL || entry->tldq_xform != NULL,
("%s: Called with both tldq_buf and tldq_xform set to NULL",
__func__));
KASSERT(entry->tldq_dtor != NULL,
("%s: Called with tldq_dtor set to NULL", __func__));
/* Get a lock on the queue. */
TCP_LOG_DEV_QUEUE_LOCK();
/* If no one is listening, tell the caller to free the resources. */
if (tcp_log_dev_listeners == 0) {
rv = ENXIO;
goto done;
}
/* Add this to the end of the tailq. */
STAILQ_INSERT_TAIL(&tcp_log_dev_queue_head, entry, tldq_queue);
/* Add references for all current listeners. */
refcount_init(&entry->tldq_refcnt, tcp_log_dev_listeners);
/*
* If any listener is currently stuck on NULL, that means they are
* waiting. Point their head to this new entry.
*/
wakeup_needed = false;
STAILQ_FOREACH(priv, &tcp_log_dev_reader_head, tldi_list)
if (priv->tldi_head == NULL) {
priv->tldi_head = entry;
wakeup_needed = true;
}
if (wakeup_needed) {
selwakeup(&tcp_log_sel);
wakeup(&tcp_log_dev_listeners);
}
rv = 0;
done:
TCP_LOG_DEV_QUEUE_LOCK_ASSERT();
TCP_LOG_DEV_QUEUE_UNLOCK();
return (rv);
}
static int
tcp_log_dev_modevent(module_t mod __unused, int type, void *data __unused)
{
/* TODO: Support intelligent unloading. */
switch (type) {
case MOD_LOAD:
if (bootverbose)
printf("tcp_log: tcp_log device\n");
memset(&tcp_log_sel, 0, sizeof(tcp_log_sel));
memset(&tcp_log_dev_queue_lock, 0, sizeof(struct mtx));
mtx_init(&tcp_log_dev_queue_lock, "tcp_log dev",
"tcp_log device queues", MTX_DEF);
tcp_log_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD,
&tcp_log_cdevsw, 0, NULL, UID_ROOT, GID_WHEEL, 0400,
"tcp_log");
break;
default:
return (EOPNOTSUPP);
}
return (0);
}
DEV_MODULE(tcp_log_dev, tcp_log_dev_modevent, NULL);
MODULE_VERSION(tcp_log_dev, 1);