linux/include/media/rc-core.h
Mauro Carvalho Chehab c73bbaa4ec [media] rc-core: don't lock device at rc_register_device()
The mutex lock at rc_register_device() was added by commit 08aeb7c9a4
("[media] rc: add locking to fix register/show race").

It is meant to avoid race issues when trying to open a sysfs file while
the RC register didn't complete.

Adding a lock there causes troubles, as detected by the Kernel lock
debug instrumentation at the Kernel:

    ======================================================
    [ INFO: possible circular locking dependency detected ]
    4.5.0-rc3+ #46 Not tainted
    -------------------------------------------------------
    systemd-udevd/2681 is trying to acquire lock:
     (s_active#171){++++.+}, at: [<ffffffff8171a115>] kernfs_remove_by_name_ns+0x45/0xa0

    but task is already holding lock:
     (&dev->lock){+.+.+.}, at: [<ffffffffa0724def>] rc_register_device+0xb2f/0x1450 [rc_core]

    which lock already depends on the new lock.

    the existing dependency chain (in reverse order) is:

    -> #1 (&dev->lock){+.+.+.}:
           [<ffffffff8124817d>] lock_acquire+0x13d/0x320
           [<ffffffff822de966>] mutex_lock_nested+0xb6/0x860
           [<ffffffffa0721f2b>] show_protocols+0x3b/0x3f0 [rc_core]
           [<ffffffff81cdaba5>] dev_attr_show+0x45/0xc0
           [<ffffffff8171f1b3>] sysfs_kf_seq_show+0x203/0x3c0
           [<ffffffff8171a6a1>] kernfs_seq_show+0x121/0x1b0
           [<ffffffff81617c71>] seq_read+0x2f1/0x1160
           [<ffffffff8171c911>] kernfs_fop_read+0x321/0x460
           [<ffffffff815abc20>] __vfs_read+0xe0/0x3d0
           [<ffffffff815ae90e>] vfs_read+0xde/0x2d0
           [<ffffffff815b1d01>] SyS_read+0x111/0x230
           [<ffffffff822e8636>] entry_SYSCALL_64_fastpath+0x16/0x76

    -> #0 (s_active#171){++++.+}:
           [<ffffffff81244f24>] __lock_acquire+0x4304/0x5990
           [<ffffffff8124817d>] lock_acquire+0x13d/0x320
           [<ffffffff81717d3a>] __kernfs_remove+0x58a/0x810
           [<ffffffff8171a115>] kernfs_remove_by_name_ns+0x45/0xa0
           [<ffffffff81721592>] remove_files.isra.0+0x72/0x190
           [<ffffffff8172174b>] sysfs_remove_group+0x9b/0x150
           [<ffffffff81721854>] sysfs_remove_groups+0x54/0xa0
           [<ffffffff81cd97d0>] device_remove_attrs+0xb0/0x140
           [<ffffffff81cdb27c>] device_del+0x38c/0x6b0
           [<ffffffffa0724b8b>] rc_register_device+0x8cb/0x1450 [rc_core]
           [<ffffffffa1326a7b>] dvb_usb_remote_init+0x66b/0x14d0 [dvb_usb]
           [<ffffffffa1321c81>] dvb_usb_device_init+0xf21/0x1860 [dvb_usb]
           [<ffffffffa13517dc>] dib0700_probe+0x14c/0x410 [dvb_usb_dib0700]
           [<ffffffff81dbb1dd>] usb_probe_interface+0x45d/0x940
           [<ffffffff81ce7e7a>] driver_probe_device+0x21a/0xc30
           [<ffffffff81ce89b1>] __driver_attach+0x121/0x160
           [<ffffffff81ce21bf>] bus_for_each_dev+0x11f/0x1a0
           [<ffffffff81ce6cdd>] driver_attach+0x3d/0x50
           [<ffffffff81ce5df9>] bus_add_driver+0x4c9/0x770
           [<ffffffff81cea39c>] driver_register+0x18c/0x3b0
           [<ffffffff81db6e98>] usb_register_driver+0x1f8/0x440
           [<ffffffffa074001e>] dib0700_driver_init+0x1e/0x1000 [dvb_usb_dib0700]
           [<ffffffff810021b1>] do_one_initcall+0x141/0x300
           [<ffffffff8144d8eb>] do_init_module+0x1d0/0x5ad
           [<ffffffff812f27b6>] load_module+0x6666/0x9ba0
           [<ffffffff812f5fe8>] SyS_finit_module+0x108/0x130
           [<ffffffff822e8636>] entry_SYSCALL_64_fastpath+0x16/0x76

    other info that might help us debug this:

     Possible unsafe locking scenario:

           CPU0                    CPU1
           ----                    ----
      lock(&dev->lock);
                                   lock(s_active#171);
                                   lock(&dev->lock);
      lock(s_active#171);

     *** DEADLOCK ***

    3 locks held by systemd-udevd/2681:
     #0:  (&dev->mutex){......}, at: [<ffffffff81ce8933>] __driver_attach+0xa3/0x160
     #1:  (&dev->mutex){......}, at: [<ffffffff81ce8941>] __driver_attach+0xb1/0x160
     #2:  (&dev->lock){+.+.+.}, at: [<ffffffffa0724def>] rc_register_device+0xb2f/0x1450 [rc_core]

In this specific case, some error happened during device init,
causing IR to be disabled.

Let's fix it by adding a var that will tell when the device is
initialized. Any calls before that will return a -EINVAL.

That should prevent the race issues.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2016-02-16 08:40:41 -02:00

284 lines
9.3 KiB
C

/*
* Remote Controller core header
*
* Copyright (C) 2009-2010 by Mauro Carvalho Chehab
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#ifndef _RC_CORE
#define _RC_CORE
#include <linux/spinlock.h>
#include <linux/kfifo.h>
#include <linux/time.h>
#include <linux/timer.h>
#include <media/rc-map.h>
extern int rc_core_debug;
#define IR_dprintk(level, fmt, ...) \
do { \
if (rc_core_debug >= level) \
printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); \
} while (0)
enum rc_driver_type {
RC_DRIVER_SCANCODE = 0, /* Driver or hardware generates a scancode */
RC_DRIVER_IR_RAW, /* Needs a Infra-Red pulse/space decoder */
};
/**
* struct rc_scancode_filter - Filter scan codes.
* @data: Scancode data to match.
* @mask: Mask of bits of scancode to compare.
*/
struct rc_scancode_filter {
u32 data;
u32 mask;
};
/**
* enum rc_filter_type - Filter type constants.
* @RC_FILTER_NORMAL: Filter for normal operation.
* @RC_FILTER_WAKEUP: Filter for waking from suspend.
* @RC_FILTER_MAX: Number of filter types.
*/
enum rc_filter_type {
RC_FILTER_NORMAL = 0,
RC_FILTER_WAKEUP,
RC_FILTER_MAX
};
/**
* struct rc_dev - represents a remote control device
* @dev: driver model's view of this device
* @initialized: true if the device init has completed
* @sysfs_groups: sysfs attribute groups
* @input_name: name of the input child device
* @input_phys: physical path to the input child device
* @input_id: id of the input child device (struct input_id)
* @driver_name: name of the hardware driver which registered this device
* @map_name: name of the default keymap
* @rc_map: current scan/key table
* @lock: used to ensure we've filled in all protocol details before
* anyone can call show_protocols or store_protocols
* @minor: unique minor remote control device number
* @raw: additional data for raw pulse/space devices
* @input_dev: the input child device used to communicate events to userspace
* @driver_type: specifies if protocol decoding is done in hardware or software
* @idle: used to keep track of RX state
* @allowed_protocols: bitmask with the supported RC_BIT_* protocols
* @enabled_protocols: bitmask with the enabled RC_BIT_* protocols
* @allowed_wakeup_protocols: bitmask with the supported RC_BIT_* wakeup protocols
* @enabled_wakeup_protocols: bitmask with the enabled RC_BIT_* wakeup protocols
* @scancode_filter: scancode filter
* @scancode_wakeup_filter: scancode wakeup filters
* @scancode_mask: some hardware decoders are not capable of providing the full
* scancode to the application. As this is a hardware limit, we can't do
* anything with it. Yet, as the same keycode table can be used with other
* devices, a mask is provided to allow its usage. Drivers should generally
* leave this field in blank
* @users: number of current users of the device
* @priv: driver-specific data
* @keylock: protects the remaining members of the struct
* @keypressed: whether a key is currently pressed
* @keyup_jiffies: time (in jiffies) when the current keypress should be released
* @timer_keyup: timer for releasing a keypress
* @last_keycode: keycode of last keypress
* @last_protocol: protocol of last keypress
* @last_scancode: scancode of last keypress
* @last_toggle: toggle value of last command
* @timeout: optional time after which device stops sending data
* @min_timeout: minimum timeout supported by device
* @max_timeout: maximum timeout supported by device
* @rx_resolution : resolution (in ns) of input sampler
* @tx_resolution: resolution (in ns) of output sampler
* @change_protocol: allow changing the protocol used on hardware decoders
* @change_wakeup_protocol: allow changing the protocol used for wakeup
* filtering
* @open: callback to allow drivers to enable polling/irq when IR input device
* is opened.
* @close: callback to allow drivers to disable polling/irq when IR input device
* is opened.
* @s_tx_mask: set transmitter mask (for devices with multiple tx outputs)
* @s_tx_carrier: set transmit carrier frequency
* @s_tx_duty_cycle: set transmit duty cycle (0% - 100%)
* @s_rx_carrier_range: inform driver about carrier it is expected to handle
* @tx_ir: transmit IR
* @s_idle: enable/disable hardware idle mode, upon which,
* device doesn't interrupt host until it sees IR pulses
* @s_learning_mode: enable wide band receiver used for learning
* @s_carrier_report: enable carrier reports
* @s_filter: set the scancode filter
* @s_wakeup_filter: set the wakeup scancode filter
*/
struct rc_dev {
struct device dev;
bool initialized;
const struct attribute_group *sysfs_groups[5];
const char *input_name;
const char *input_phys;
struct input_id input_id;
char *driver_name;
const char *map_name;
struct rc_map rc_map;
struct mutex lock;
unsigned int minor;
struct ir_raw_event_ctrl *raw;
struct input_dev *input_dev;
enum rc_driver_type driver_type;
bool idle;
u64 allowed_protocols;
u64 enabled_protocols;
u64 allowed_wakeup_protocols;
u64 enabled_wakeup_protocols;
struct rc_scancode_filter scancode_filter;
struct rc_scancode_filter scancode_wakeup_filter;
u32 scancode_mask;
u32 users;
void *priv;
spinlock_t keylock;
bool keypressed;
unsigned long keyup_jiffies;
struct timer_list timer_keyup;
u32 last_keycode;
enum rc_type last_protocol;
u32 last_scancode;
u8 last_toggle;
u32 timeout;
u32 min_timeout;
u32 max_timeout;
u32 rx_resolution;
u32 tx_resolution;
int (*change_protocol)(struct rc_dev *dev, u64 *rc_type);
int (*change_wakeup_protocol)(struct rc_dev *dev, u64 *rc_type);
int (*open)(struct rc_dev *dev);
void (*close)(struct rc_dev *dev);
int (*s_tx_mask)(struct rc_dev *dev, u32 mask);
int (*s_tx_carrier)(struct rc_dev *dev, u32 carrier);
int (*s_tx_duty_cycle)(struct rc_dev *dev, u32 duty_cycle);
int (*s_rx_carrier_range)(struct rc_dev *dev, u32 min, u32 max);
int (*tx_ir)(struct rc_dev *dev, unsigned *txbuf, unsigned n);
void (*s_idle)(struct rc_dev *dev, bool enable);
int (*s_learning_mode)(struct rc_dev *dev, int enable);
int (*s_carrier_report) (struct rc_dev *dev, int enable);
int (*s_filter)(struct rc_dev *dev,
struct rc_scancode_filter *filter);
int (*s_wakeup_filter)(struct rc_dev *dev,
struct rc_scancode_filter *filter);
};
#define to_rc_dev(d) container_of(d, struct rc_dev, dev)
/*
* From rc-main.c
* Those functions can be used on any type of Remote Controller. They
* basically creates an input_dev and properly reports the device as a
* Remote Controller, at sys/class/rc.
*/
struct rc_dev *rc_allocate_device(void);
void rc_free_device(struct rc_dev *dev);
int rc_register_device(struct rc_dev *dev);
void rc_unregister_device(struct rc_dev *dev);
int rc_open(struct rc_dev *rdev);
void rc_close(struct rc_dev *rdev);
void rc_repeat(struct rc_dev *dev);
void rc_keydown(struct rc_dev *dev, enum rc_type protocol, u32 scancode, u8 toggle);
void rc_keydown_notimeout(struct rc_dev *dev, enum rc_type protocol, u32 scancode, u8 toggle);
void rc_keyup(struct rc_dev *dev);
u32 rc_g_keycode_from_table(struct rc_dev *dev, u32 scancode);
/*
* From rc-raw.c
* The Raw interface is specific to InfraRed. It may be a good idea to
* split it later into a separate header.
*/
enum raw_event_type {
IR_SPACE = (1 << 0),
IR_PULSE = (1 << 1),
IR_START_EVENT = (1 << 2),
IR_STOP_EVENT = (1 << 3),
};
struct ir_raw_event {
union {
u32 duration;
struct {
u32 carrier;
u8 duty_cycle;
};
};
unsigned pulse:1;
unsigned reset:1;
unsigned timeout:1;
unsigned carrier_report:1;
};
#define DEFINE_IR_RAW_EVENT(event) \
struct ir_raw_event event = { \
{ .duration = 0 } , \
.pulse = 0, \
.reset = 0, \
.timeout = 0, \
.carrier_report = 0 }
static inline void init_ir_raw_event(struct ir_raw_event *ev)
{
memset(ev, 0, sizeof(*ev));
}
#define IR_DEFAULT_TIMEOUT MS_TO_NS(125)
#define IR_MAX_DURATION 500000000 /* 500 ms */
#define US_TO_NS(usec) ((usec) * 1000)
#define MS_TO_US(msec) ((msec) * 1000)
#define MS_TO_NS(msec) ((msec) * 1000 * 1000)
void ir_raw_event_handle(struct rc_dev *dev);
int ir_raw_event_store(struct rc_dev *dev, struct ir_raw_event *ev);
int ir_raw_event_store_edge(struct rc_dev *dev, enum raw_event_type type);
int ir_raw_event_store_with_filter(struct rc_dev *dev,
struct ir_raw_event *ev);
void ir_raw_event_set_idle(struct rc_dev *dev, bool idle);
static inline void ir_raw_event_reset(struct rc_dev *dev)
{
DEFINE_IR_RAW_EVENT(ev);
ev.reset = true;
ir_raw_event_store(dev, &ev);
ir_raw_event_handle(dev);
}
/* extract mask bits out of data and pack them into the result */
static inline u32 ir_extract_bits(u32 data, u32 mask)
{
u32 vbit = 1, value = 0;
do {
if (mask & 1) {
if (data & 1)
value |= vbit;
vbit <<= 1;
}
data >>= 1;
} while (mask >>= 1);
return value;
}
#endif /* _RC_CORE */