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USB: core: remove polling for /sys/kernel/debug/usb/devices 

The latest reference to usbfs_conn_disc_event() removed in
commit fb28d58b72 ("USB: remove CONFIG_USB_DEVICEFS")
in 2012 and now a user poll() waits infinitely for content changes.

Signed-off-by: Sergey Korolev <s.korolev@ndmsystems.com>
Link: https://lore.kernel.org/r/20200809161233.13135-1-s.korolev@ndmsystems.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sergey Korolev 2020-08-09 19:12:30 +03:00 committed by Greg Kroah-Hartman
parent da0cb63100
commit 97b65223c1
2 changed files with 0 additions and 42 deletions
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41
drivers/usb/core/devices.c
View File

@ -39,7 +39,6 @@
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/poll.h>
#include <linux/usb.h>
#include <linux/usbdevice_fs.h>
#include <linux/usb/hcd.h>
@ -97,22 +96,6 @@ static const char format_endpt[] =
/* E: Ad=xx(s) Atr=xx(ssss) MxPS=dddd Ivl=D?s */
"E: Ad=%02x(%c) Atr=%02x(%-4s) MxPS=%4d Ivl=%d%cs\n";
/*
* Wait for an connect/disconnect event to happen. We initialize
* the event counter with an odd number, and each event will increment
* the event counter by two, so it will always _stay_ odd. That means
* that it will never be zero, so "event 0" will never match a current
* event, and thus 'poll' will always trigger as readable for the first
* time it gets called.
*/
static struct device_connect_event {
atomic_t count;
wait_queue_head_t wait;
} device_event = {
.count = ATOMIC_INIT(1),
.wait = __WAIT_QUEUE_HEAD_INITIALIZER(device_event.wait)
};
struct class_info {
int class;
char *class_name;
@ -146,12 +129,6 @@ static const struct class_info clas_info[] = {
/*****************************************************************/
void usbfs_conn_disc_event(void)
{
atomic_add(2, &device_event.count);
wake_up(&device_event.wait);
}
static const char *class_decode(const int class)
{
int ix;
@ -623,25 +600,7 @@ static ssize_t usb_device_read(struct file *file, char __user *buf,
return total_written;
}
/* Kernel lock for "lastev" protection */
static __poll_t usb_device_poll(struct file *file,
struct poll_table_struct *wait)
{
unsigned int event_count;
poll_wait(file, &device_event.wait, wait);
event_count = atomic_read(&device_event.count);
if (file->f_version != event_count) {
file->f_version = event_count;
return EPOLLIN | EPOLLRDNORM;
}
return 0;
}
const struct file_operations usbfs_devices_fops = {
.llseek = no_seek_end_llseek,
.read = usb_device_read,
.poll = usb_device_poll,
};

1
drivers/usb/core/usb.h
View File

@ -191,7 +191,6 @@ extern const struct attribute_group *usb_interface_groups[];
extern struct usb_driver usbfs_driver;
extern const struct file_operations usbfs_devices_fops;
extern const struct file_operations usbdev_file_operations;
extern void usbfs_conn_disc_event(void);
extern int usb_devio_init(void);
extern void usb_devio_cleanup(void);