linux/drivers/ptp/ptp_private.h
Eric Dumazet 73bde5a329 ptp: annotate data-race around q->head and q->tail
As I was working on a syzbot report, I found that KCSAN would
probably complain that reading q->head or q->tail without
barriers could lead to invalid results.

Add corresponding READ_ONCE() and WRITE_ONCE() to avoid
load-store tearing.

Fixes: d94ba80ebb ("ptp: Added a brand new class driver for ptp clocks.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Link: https://lore.kernel.org/r/20231109174859.3995880-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-11-13 20:51:37 -08:00

158 lines
4.4 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* PTP 1588 clock support - private declarations for the core module.
*
* Copyright (C) 2010 OMICRON electronics GmbH
*/
#ifndef _PTP_PRIVATE_H_
#define _PTP_PRIVATE_H_
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/posix-clock.h>
#include <linux/ptp_clock.h>
#include <linux/ptp_clock_kernel.h>
#include <linux/time.h>
#include <linux/list.h>
#include <linux/bitmap.h>
#include <linux/debugfs.h>
#define PTP_MAX_TIMESTAMPS 128
#define PTP_BUF_TIMESTAMPS 30
#define PTP_DEFAULT_MAX_VCLOCKS 20
#define PTP_MAX_CHANNELS 2048
struct timestamp_event_queue {
struct ptp_extts_event buf[PTP_MAX_TIMESTAMPS];
int head;
int tail;
spinlock_t lock;
struct list_head qlist;
unsigned long *mask;
struct dentry *debugfs_instance;
struct debugfs_u32_array dfs_bitmap;
};
struct ptp_clock {
struct posix_clock clock;
struct device dev;
struct ptp_clock_info *info;
dev_t devid;
int index; /* index into clocks.map */
struct pps_device *pps_source;
long dialed_frequency; /* remembers the frequency adjustment */
struct list_head tsevqs; /* timestamp fifo list */
spinlock_t tsevqs_lock; /* protects tsevqs from concurrent access */
struct mutex pincfg_mux; /* protect concurrent info->pin_config access */
wait_queue_head_t tsev_wq;
int defunct; /* tells readers to go away when clock is being removed */
struct device_attribute *pin_dev_attr;
struct attribute **pin_attr;
struct attribute_group pin_attr_group;
/* 1st entry is a pointer to the real group, 2nd is NULL terminator */
const struct attribute_group *pin_attr_groups[2];
struct kthread_worker *kworker;
struct kthread_delayed_work aux_work;
unsigned int max_vclocks;
unsigned int n_vclocks;
int *vclock_index;
struct mutex n_vclocks_mux; /* protect concurrent n_vclocks access */
bool is_virtual_clock;
bool has_cycles;
struct dentry *debugfs_root;
};
#define info_to_vclock(d) container_of((d), struct ptp_vclock, info)
#define cc_to_vclock(d) container_of((d), struct ptp_vclock, cc)
#define dw_to_vclock(d) container_of((d), struct ptp_vclock, refresh_work)
struct ptp_vclock {
struct ptp_clock *pclock;
struct ptp_clock_info info;
struct ptp_clock *clock;
struct hlist_node vclock_hash_node;
struct cyclecounter cc;
struct timecounter tc;
struct mutex lock; /* protects tc/cc */
};
/*
* The function queue_cnt() is safe for readers to call without
* holding q->lock. Readers use this function to verify that the queue
* is nonempty before proceeding with a dequeue operation. The fact
* that a writer might concurrently increment the tail does not
* matter, since the queue remains nonempty nonetheless.
*/
static inline int queue_cnt(const struct timestamp_event_queue *q)
{
/*
* Paired with WRITE_ONCE() in enqueue_external_timestamp(),
* ptp_read(), extts_fifo_show().
*/
int cnt = READ_ONCE(q->tail) - READ_ONCE(q->head);
return cnt < 0 ? PTP_MAX_TIMESTAMPS + cnt : cnt;
}
/* Check if ptp virtual clock is in use */
static inline bool ptp_vclock_in_use(struct ptp_clock *ptp)
{
bool in_use = false;
if (mutex_lock_interruptible(&ptp->n_vclocks_mux))
return true;
if (!ptp->is_virtual_clock && ptp->n_vclocks)
in_use = true;
mutex_unlock(&ptp->n_vclocks_mux);
return in_use;
}
/* Check if ptp clock shall be free running */
static inline bool ptp_clock_freerun(struct ptp_clock *ptp)
{
if (ptp->has_cycles)
return false;
return ptp_vclock_in_use(ptp);
}
extern struct class *ptp_class;
/*
* see ptp_chardev.c
*/
/* caller must hold pincfg_mux */
int ptp_set_pinfunc(struct ptp_clock *ptp, unsigned int pin,
enum ptp_pin_function func, unsigned int chan);
long ptp_ioctl(struct posix_clock_context *pccontext, unsigned int cmd,
unsigned long arg);
int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode);
int ptp_release(struct posix_clock_context *pccontext);
ssize_t ptp_read(struct posix_clock_context *pccontext, uint flags, char __user *buf,
size_t cnt);
__poll_t ptp_poll(struct posix_clock_context *pccontext, struct file *fp,
poll_table *wait);
/*
* see ptp_sysfs.c
*/
extern const struct attribute_group *ptp_groups[];
int ptp_populate_pin_groups(struct ptp_clock *ptp);
void ptp_cleanup_pin_groups(struct ptp_clock *ptp);
struct ptp_vclock *ptp_vclock_register(struct ptp_clock *pclock);
void ptp_vclock_unregister(struct ptp_vclock *vclock);
#endif