Revision 382225e62bdb8059b7f915b133426425516dd300 authored by Takashi Iwai on 22 February 2011, 09:21:18 UTC, committed by Takashi Iwai on 23 February 2011, 07:15:43 UTC
When a USB audio device is disconnected, snd_usb_audio_disconnect() kills all audio URBs. At the same time, the application, after being notified of the disconnection, might close the device, in which case ALSA calls the .hw_free callback, which should free the URBs too. Commit de1b8b93a0ba "[ALSA] Fix hang-up at disconnection of usb-audio" prevented snd_usb_hw_free() from freeing the URBs to avoid a hang that resulted from this race, but this introduced another race because the URB callbacks could now be executed after snd_usb_hw_free() has returned, and try to access already freed data. Fix the first race by introducing a mutex to serialize the disconnect callback and all PCM callbacks that manage URBs (hw_free and hw_params). Reported-and-tested-by: Pierre-Louis Bossart <pierre-louis.bossart@intel.com> Cc: <stable@kernel.org> [CL: also serialize hw_params callback] Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Signed-off-by: Takashi Iwai <tiwai@suse.de>
1 parent 3064967
kmod.h
#ifndef __LINUX_KMOD_H__
#define __LINUX_KMOD_H__
/*
* include/linux/kmod.h
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/gfp.h>
#include <linux/stddef.h>
#include <linux/errno.h>
#include <linux/compiler.h>
#include <linux/workqueue.h>
#define KMOD_PATH_LEN 256
#ifdef CONFIG_MODULES
extern char modprobe_path[]; /* for sysctl */
/* modprobe exit status on success, -ve on error. Return value
* usually useless though. */
extern int __request_module(bool wait, const char *name, ...) \
__attribute__((format(printf, 2, 3)));
#define request_module(mod...) __request_module(true, mod)
#define request_module_nowait(mod...) __request_module(false, mod)
#define try_then_request_module(x, mod...) \
((x) ?: (__request_module(true, mod), (x)))
#else
static inline int request_module(const char *name, ...) { return -ENOSYS; }
static inline int request_module_nowait(const char *name, ...) { return -ENOSYS; }
#define try_then_request_module(x, mod...) (x)
#endif
struct key;
struct file;
enum umh_wait {
UMH_NO_WAIT = -1, /* don't wait at all */
UMH_WAIT_EXEC = 0, /* wait for the exec, but not the process */
UMH_WAIT_PROC = 1, /* wait for the process to complete */
};
struct subprocess_info {
struct work_struct work;
struct completion *complete;
char *path;
char **argv;
char **envp;
enum umh_wait wait;
int retval;
int (*init)(struct subprocess_info *info);
void (*cleanup)(struct subprocess_info *info);
void *data;
};
/* Allocate a subprocess_info structure */
struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
char **envp, gfp_t gfp_mask);
/* Set various pieces of state into the subprocess_info structure */
void call_usermodehelper_setfns(struct subprocess_info *info,
int (*init)(struct subprocess_info *info),
void (*cleanup)(struct subprocess_info *info),
void *data);
/* Actually execute the sub-process */
int call_usermodehelper_exec(struct subprocess_info *info, enum umh_wait wait);
/* Free the subprocess_info. This is only needed if you're not going
to call call_usermodehelper_exec */
void call_usermodehelper_freeinfo(struct subprocess_info *info);
static inline int
call_usermodehelper_fns(char *path, char **argv, char **envp,
enum umh_wait wait,
int (*init)(struct subprocess_info *info),
void (*cleanup)(struct subprocess_info *), void *data)
{
struct subprocess_info *info;
gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
if (info == NULL)
return -ENOMEM;
call_usermodehelper_setfns(info, init, cleanup, data);
return call_usermodehelper_exec(info, wait);
}
static inline int
call_usermodehelper(char *path, char **argv, char **envp, enum umh_wait wait)
{
return call_usermodehelper_fns(path, argv, envp, wait,
NULL, NULL, NULL);
}
extern void usermodehelper_init(void);
extern int usermodehelper_disable(void);
extern void usermodehelper_enable(void);
#endif /* __LINUX_KMOD_H__ */
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