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linux-next/drivers/hwtracing/stm/stm.h
Alexander Shishkin cde4ad8368 stm class: Guard output assignment against concurrency
It is possible to concurrently assign the same output (a character
device writer or an stm_source device) to different stm devices,
which sets off a strategically placed warning in stm_output_assign().

To avoid this, use a spinlock to serialize (un)assignments between
outputs and stm devices.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-20 14:09:14 -08:00

90 lines
2.3 KiB
C

/*
* System Trace Module (STM) infrastructure
* Copyright (c) 2014, Intel Corporation.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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.
*
* STM class implements generic infrastructure for System Trace Module devices
* as defined in MIPI STPv2 specification.
*/
#ifndef _STM_STM_H_
#define _STM_STM_H_
struct stp_policy;
struct stp_policy_node;
struct stp_policy_node *
stp_policy_node_lookup(struct stm_device *stm, char *s);
void stp_policy_node_put(struct stp_policy_node *policy_node);
void stp_policy_unbind(struct stp_policy *policy);
void stp_policy_node_get_ranges(struct stp_policy_node *policy_node,
unsigned int *mstart, unsigned int *mend,
unsigned int *cstart, unsigned int *cend);
int stp_configfs_init(void);
void stp_configfs_exit(void);
struct stp_master {
unsigned int nr_free;
unsigned long chan_map[0];
};
struct stm_device {
struct device dev;
struct module *owner;
struct stp_policy *policy;
struct mutex policy_mutex;
int major;
unsigned int sw_nmasters;
struct stm_data *data;
struct mutex link_mutex;
spinlock_t link_lock;
struct list_head link_list;
/* master allocation */
spinlock_t mc_lock;
struct stp_master *masters[0];
};
#define to_stm_device(_d) \
container_of((_d), struct stm_device, dev)
struct stm_output {
spinlock_t lock;
unsigned int master;
unsigned int channel;
unsigned int nr_chans;
};
struct stm_file {
struct stm_device *stm;
struct stp_policy_node *policy_node;
struct stm_output output;
};
struct stm_device *stm_find_device(const char *name);
void stm_put_device(struct stm_device *stm);
struct stm_source_device {
struct device dev;
struct stm_source_data *data;
spinlock_t link_lock;
struct stm_device __rcu *link;
struct list_head link_entry;
/* one output per stm_source device */
struct stp_policy_node *policy_node;
struct stm_output output;
};
#define to_stm_source_device(_d) \
container_of((_d), struct stm_source_device, dev)
#endif /* _STM_STM_H_ */