Revision 9107c89e269d2738019861bb518e3d59bef01781 authored by Peter Zijlstra on 24 February 2016, 17:45:45 UTC, committed by Ingo Molnar on 25 February 2016, 07:42:34 UTC
perf_install_in_context() relies upon the context switch hooks to have scheduled in events when the IPI misses its target -- after all, if the task has moved from the CPU (or wasn't running at all), it will have to context switch to run elsewhere. This however doesn't appear to be happening. It is possible for the IPI to not happen (task wasn't running) only to later observe the task running with an inactive context. The only possible explanation is that the context switch hooks are not called. Therefore put in a sync_sched() after toggling the jump_label to guarantee all CPUs will have them enabled before we install an event. A simple if (0->1) sync_sched() will not in fact work, because any further increment can race and complete before the sync_sched(). Therefore we must jump through some hoops. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dvyukov@google.com Cc: eranian@google.com Cc: oleg@redhat.com Cc: panand@redhat.com Cc: sasha.levin@oracle.com Cc: vince@deater.net Link: http://lkml.kernel.org/r/20160224174947.980211985@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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hostaudio_kern.c
/*
* Copyright (C) 2002 Steve Schmidtke
* Licensed under the GPL
*/
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sound.h>
#include <linux/soundcard.h>
#include <linux/mutex.h>
#include <asm/uaccess.h>
#include <init.h>
#include <os.h>
struct hostaudio_state {
int fd;
};
struct hostmixer_state {
int fd;
};
#define HOSTAUDIO_DEV_DSP "/dev/sound/dsp"
#define HOSTAUDIO_DEV_MIXER "/dev/sound/mixer"
/*
* Changed either at boot time or module load time. At boot, this is
* single-threaded; at module load, multiple modules would each have
* their own copy of these variables.
*/
static char *dsp = HOSTAUDIO_DEV_DSP;
static char *mixer = HOSTAUDIO_DEV_MIXER;
#define DSP_HELP \
" This is used to specify the host dsp device to the hostaudio driver.\n" \
" The default is \"" HOSTAUDIO_DEV_DSP "\".\n\n"
#define MIXER_HELP \
" This is used to specify the host mixer device to the hostaudio driver.\n"\
" The default is \"" HOSTAUDIO_DEV_MIXER "\".\n\n"
module_param(dsp, charp, 0644);
MODULE_PARM_DESC(dsp, DSP_HELP);
module_param(mixer, charp, 0644);
MODULE_PARM_DESC(mixer, MIXER_HELP);
#ifndef MODULE
static int set_dsp(char *name, int *add)
{
dsp = name;
return 0;
}
__uml_setup("dsp=", set_dsp, "dsp=<dsp device>\n" DSP_HELP);
static int set_mixer(char *name, int *add)
{
mixer = name;
return 0;
}
__uml_setup("mixer=", set_mixer, "mixer=<mixer device>\n" MIXER_HELP);
#endif
static DEFINE_MUTEX(hostaudio_mutex);
/* /dev/dsp file operations */
static ssize_t hostaudio_read(struct file *file, char __user *buffer,
size_t count, loff_t *ppos)
{
struct hostaudio_state *state = file->private_data;
void *kbuf;
int err;
#ifdef DEBUG
printk(KERN_DEBUG "hostaudio: read called, count = %d\n", count);
#endif
kbuf = kmalloc(count, GFP_KERNEL);
if (kbuf == NULL)
return -ENOMEM;
err = os_read_file(state->fd, kbuf, count);
if (err < 0)
goto out;
if (copy_to_user(buffer, kbuf, err))
err = -EFAULT;
out:
kfree(kbuf);
return err;
}
static ssize_t hostaudio_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
struct hostaudio_state *state = file->private_data;
void *kbuf;
int err;
#ifdef DEBUG
printk(KERN_DEBUG "hostaudio: write called, count = %d\n", count);
#endif
kbuf = memdup_user(buffer, count);
if (IS_ERR(kbuf))
return PTR_ERR(kbuf);
err = os_write_file(state->fd, kbuf, count);
if (err < 0)
goto out;
*ppos += err;
out:
kfree(kbuf);
return err;
}
static unsigned int hostaudio_poll(struct file *file,
struct poll_table_struct *wait)
{
unsigned int mask = 0;
#ifdef DEBUG
printk(KERN_DEBUG "hostaudio: poll called (unimplemented)\n");
#endif
return mask;
}
static long hostaudio_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
struct hostaudio_state *state = file->private_data;
unsigned long data = 0;
int err;
#ifdef DEBUG
printk(KERN_DEBUG "hostaudio: ioctl called, cmd = %u\n", cmd);
#endif
switch(cmd){
case SNDCTL_DSP_SPEED:
case SNDCTL_DSP_STEREO:
case SNDCTL_DSP_GETBLKSIZE:
case SNDCTL_DSP_CHANNELS:
case SNDCTL_DSP_SUBDIVIDE:
case SNDCTL_DSP_SETFRAGMENT:
if (get_user(data, (int __user *) arg))
return -EFAULT;
break;
default:
break;
}
err = os_ioctl_generic(state->fd, cmd, (unsigned long) &data);
switch(cmd){
case SNDCTL_DSP_SPEED:
case SNDCTL_DSP_STEREO:
case SNDCTL_DSP_GETBLKSIZE:
case SNDCTL_DSP_CHANNELS:
case SNDCTL_DSP_SUBDIVIDE:
case SNDCTL_DSP_SETFRAGMENT:
if (put_user(data, (int __user *) arg))
return -EFAULT;
break;
default:
break;
}
return err;
}
static int hostaudio_open(struct inode *inode, struct file *file)
{
struct hostaudio_state *state;
int r = 0, w = 0;
int ret;
#ifdef DEBUG
kernel_param_lock(THIS_MODULE);
printk(KERN_DEBUG "hostaudio: open called (host: %s)\n", dsp);
kernel_param_unlock(THIS_MODULE);
#endif
state = kmalloc(sizeof(struct hostaudio_state), GFP_KERNEL);
if (state == NULL)
return -ENOMEM;
if (file->f_mode & FMODE_READ)
r = 1;
if (file->f_mode & FMODE_WRITE)
w = 1;
kernel_param_lock(THIS_MODULE);
mutex_lock(&hostaudio_mutex);
ret = os_open_file(dsp, of_set_rw(OPENFLAGS(), r, w), 0);
mutex_unlock(&hostaudio_mutex);
kernel_param_unlock(THIS_MODULE);
if (ret < 0) {
kfree(state);
return ret;
}
state->fd = ret;
file->private_data = state;
return 0;
}
static int hostaudio_release(struct inode *inode, struct file *file)
{
struct hostaudio_state *state = file->private_data;
#ifdef DEBUG
printk(KERN_DEBUG "hostaudio: release called\n");
#endif
os_close_file(state->fd);
kfree(state);
return 0;
}
/* /dev/mixer file operations */
static long hostmixer_ioctl_mixdev(struct file *file,
unsigned int cmd, unsigned long arg)
{
struct hostmixer_state *state = file->private_data;
#ifdef DEBUG
printk(KERN_DEBUG "hostmixer: ioctl called\n");
#endif
return os_ioctl_generic(state->fd, cmd, arg);
}
static int hostmixer_open_mixdev(struct inode *inode, struct file *file)
{
struct hostmixer_state *state;
int r = 0, w = 0;
int ret;
#ifdef DEBUG
printk(KERN_DEBUG "hostmixer: open called (host: %s)\n", mixer);
#endif
state = kmalloc(sizeof(struct hostmixer_state), GFP_KERNEL);
if (state == NULL)
return -ENOMEM;
if (file->f_mode & FMODE_READ)
r = 1;
if (file->f_mode & FMODE_WRITE)
w = 1;
kernel_param_lock(THIS_MODULE);
mutex_lock(&hostaudio_mutex);
ret = os_open_file(mixer, of_set_rw(OPENFLAGS(), r, w), 0);
mutex_unlock(&hostaudio_mutex);
kernel_param_unlock(THIS_MODULE);
if (ret < 0) {
kernel_param_lock(THIS_MODULE);
printk(KERN_ERR "hostaudio_open_mixdev failed to open '%s', "
"err = %d\n", dsp, -ret);
kernel_param_unlock(THIS_MODULE);
kfree(state);
return ret;
}
file->private_data = state;
return 0;
}
static int hostmixer_release(struct inode *inode, struct file *file)
{
struct hostmixer_state *state = file->private_data;
#ifdef DEBUG
printk(KERN_DEBUG "hostmixer: release called\n");
#endif
os_close_file(state->fd);
kfree(state);
return 0;
}
/* kernel module operations */
static const struct file_operations hostaudio_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.read = hostaudio_read,
.write = hostaudio_write,
.poll = hostaudio_poll,
.unlocked_ioctl = hostaudio_ioctl,
.mmap = NULL,
.open = hostaudio_open,
.release = hostaudio_release,
};
static const struct file_operations hostmixer_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.unlocked_ioctl = hostmixer_ioctl_mixdev,
.open = hostmixer_open_mixdev,
.release = hostmixer_release,
};
struct {
int dev_audio;
int dev_mixer;
} module_data;
MODULE_AUTHOR("Steve Schmidtke");
MODULE_DESCRIPTION("UML Audio Relay");
MODULE_LICENSE("GPL");
static int __init hostaudio_init_module(void)
{
kernel_param_lock(THIS_MODULE);
printk(KERN_INFO "UML Audio Relay (host dsp = %s, host mixer = %s)\n",
dsp, mixer);
kernel_param_unlock(THIS_MODULE);
module_data.dev_audio = register_sound_dsp(&hostaudio_fops, -1);
if (module_data.dev_audio < 0) {
printk(KERN_ERR "hostaudio: couldn't register DSP device!\n");
return -ENODEV;
}
module_data.dev_mixer = register_sound_mixer(&hostmixer_fops, -1);
if (module_data.dev_mixer < 0) {
printk(KERN_ERR "hostmixer: couldn't register mixer "
"device!\n");
unregister_sound_dsp(module_data.dev_audio);
return -ENODEV;
}
return 0;
}
static void __exit hostaudio_cleanup_module (void)
{
unregister_sound_mixer(module_data.dev_mixer);
unregister_sound_dsp(module_data.dev_audio);
}
module_init(hostaudio_init_module);
module_exit(hostaudio_cleanup_module);
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