linux-imx

// SPDX-License-Identifier: GPL-2.0

#include <linux/errno.h>

#include <linux/numa.h>

#include <linux/slab.h>

#include <linux/rculist.h>

#include <linux/threads.h>

#include <linux/preempt.h>

#include <linux/irqflags.h>

#include <linux/vmalloc.h>

#include <linux/mm.h>

#include <linux/module.h>

#include <linux/device-mapper.h>

​

#include "dm-core.h"

#include "dm-stats.h"

​

#define DM_MSG_PREFIX "stats"

​

static int dm_stat_need_rcu_barrier;

​

/*

 * Using 64-bit values to avoid overflow (which is a

 * problem that block/genhd.c's IO accounting has).

 */

struct dm_stat_percpu {

    unsigned long long sectors[2];

    unsigned long long ios[2];

    unsigned long long merges[2];

    unsigned long long ticks[2];

    unsigned long long io_ticks[2];

    unsigned long long io_ticks_total;

    unsigned long long time_in_queue;

    unsigned long long *histogram;

};

​

struct dm_stat_shared {

    atomic_t in_flight[2];

    unsigned long long stamp;

    struct dm_stat_percpu tmp;

};

​

struct dm_stat {

    struct list_head list_entry;

    int id;

    unsigned stat_flags;

    size_t n_entries;

    sector_t start;

    sector_t end;

    sector_t step;

    unsigned n_histogram_entries;

    unsigned long long *histogram_boundaries;

    const char *program_id;

    const char *aux_data;

    struct rcu_head rcu_head;

    size_t shared_alloc_size;

    size_t percpu_alloc_size;

    size_t histogram_alloc_size;

    struct dm_stat_percpu *stat_percpu[NR_CPUS];

    struct dm_stat_shared stat_shared[0];

};

​

#define STAT_PRECISE_TIMESTAMPS     1

​

struct dm_stats_last_position {

    sector_t last_sector;

    unsigned last_rw;

};

​

/*

 * A typo on the command line could possibly make the kernel run out of memory

 * and crash. To prevent the crash we account all used memory. We fail if we

 * exhaust 1/4 of all memory or 1/2 of vmalloc space.

 */

#define DM_STATS_MEMORY_FACTOR      4

#define DM_STATS_VMALLOC_FACTOR     2

​

static DEFINE_SPINLOCK(shared_memory_lock);

​

static unsigned long shared_memory_amount;

​

static bool __check_shared_memory(size_t alloc_size)

{

    size_t a;

​

    a = shared_memory_amount + alloc_size;

    if (a < shared_memory_amount)

        return false;

    if (a >> PAGE_SHIFT > totalram_pages() / DM_STATS_MEMORY_FACTOR)

        return false;

#ifdef CONFIG_MMU

    if (a > (VMALLOC_END - VMALLOC_START) / DM_STATS_VMALLOC_FACTOR)

        return false;