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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2008 Advanced Micro Devices, Inc.
  *
  * Author: Joerg Roedel <joerg.roedel@amd.com>
  */
 
 #define pr_fmt(fmt) "DMA-API: " fmt
 
 #include <linux/sched/task_stack.h>
 #include <linux/scatterlist.h>
 #include <linux/dma-map-ops.h>
 #include <linux/sched/task.h>
 #include <linux/stacktrace.h>
 #include <linux/spinlock.h>
 #include <linux/vmalloc.h>
 #include <linux/debugfs.h>
 #include <linux/uaccess.h>
 #include <linux/export.h>
 #include <linux/device.h>
 #include <linux/types.h>
 #include <linux/sched.h>
 #include <linux/ctype.h>
 #include <linux/list.h>
 #include <linux/slab.h>
 #include <asm/sections.h>
 #include "debug.h"
 
 #define HASH_SIZE       16384ULL
 #define HASH_FN_SHIFT   13
 #define HASH_FN_MASK    (HASH_SIZE - 1)
 
 #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
 /* If the pool runs out, add this many new entries at once */
 #define DMA_DEBUG_DYNAMIC_ENTRIES (PAGE_SIZE / sizeof(struct dma_debug_entry))
 
 enum {
     dma_debug_single,
     dma_debug_sg,
     dma_debug_coherent,
     dma_debug_resource,
 };
 
 enum map_err_types {
     MAP_ERR_CHECK_NOT_APPLICABLE,
     MAP_ERR_NOT_CHECKED,
     MAP_ERR_CHECKED,
 };
 
 #define DMA_DEBUG_STACKTRACE_ENTRIES 5
 
 /**
  * struct dma_debug_entry - track a dma_map* or dma_alloc_coherent mapping
  * @list: node on pre-allocated free_entries list
  * @dev: 'dev' argument to dma_map_{page|single|sg} or dma_alloc_coherent
  * @size: length of the mapping
  * @type: single, page, sg, coherent
  * @direction: enum dma_data_direction
  * @sg_call_ents: 'nents' from dma_map_sg
  * @sg_mapped_ents: 'mapped_ents' from dma_map_sg
  * @pfn: page frame of the start address
  * @offset: offset of mapping relative to pfn
  * @map_err_type: track whether dma_mapping_error() was checked
  * @stacktrace: support backtraces when a violation is detected
  */
 struct dma_debug_entry {
     struct list_head list;
     struct device    *dev;
     u64              dev_addr;
     u64              size;
     int              type;
     int              direction;
     int      sg_call_ents;
     int      sg_mapped_ents;
     unsigned long    pfn;
     size_t       offset;
     enum map_err_types  map_err_type;
 #ifdef CONFIG_STACKTRACE
     unsigned int    stack_len;
     unsigned long   stack_entries[DMA_DEBUG_STACKTRACE_ENTRIES];
 #endif
 } ____cacheline_aligned_in_smp;
 
 typedef bool (*match_fn)(struct dma_debug_entry *, struct dma_debug_entry *);
 
 struct hash_bucket {
     struct list_head list;
     spinlock_t lock;
 };
 
 /* Hash list to save the allocated dma addresses */
 static struct hash_bucket dma_entry_hash[HASH_SIZE];
 /* List of pre-allocated dma_debug_entry's */
 static LIST_HEAD(free_entries);
 /* Lock for the list above */
 static DEFINE_SPINLOCK(free_entries_lock);
 
 /* Global disable flag - will be set in case of an error */
 static bool global_disable __read_mostly;
 
 /* Early initialization disable flag, set at the end of dma_debug_init */
 static bool dma_debug_initialized __read_mostly;
 
 static inline bool dma_debug_disabled(void)
 {
     return global_disable || !dma_debug_initialized;
 }
 
 /* Global error count */
 static u32 error_count;
 
 /* Global error show enable*/
 static u32 show_all_errors __read_mostly;
 /* Number of errors to show */
 static u32 show_num_errors = 1;
 
 static u32 num_free_entries;
 static u32 min_free_entries;
 static u32 nr_total_entries;
 
 /* number of preallocated entries requested by kernel cmdline */
 static u32 nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;
 
 /* per-driver filter related state */
 
 #define NAME_MAX_LEN    64
 
 static char                  current_driver_name[NAME_MAX_LEN] __read_mostly;
 static struct device_driver *current_driver                    __read_mostly;
 
 static DEFINE_RWLOCK(driver_name_lock);
 
 static const char *const maperr2str[] = {
     [MAP_ERR_CHECK_NOT_APPLICABLE] = "dma map error check not applicable",
     [MAP_ERR_NOT_CHECKED] = "dma map error not checked",
     [MAP_ERR_CHECKED] = "dma map error checked",
 };
 
 static const char *type2name[] = {
     [dma_debug_single] = "single",
     [dma_debug_sg] = "scather-gather",
     [dma_debug_coherent] = "coherent",
     [dma_debug_resource] = "resource",
 };
 
 static const char *dir2name[] = {
     [DMA_BIDIRECTIONAL] = "DMA_BIDIRECTIONAL",
     [DMA_TO_DEVICE]     = "DMA_TO_DEVICE",
     [DMA_FROM_DEVICE]   = "DMA_FROM_DEVICE",
     [DMA_NONE]      = "DMA_NONE",
 };
 
 /*
  * The access to some variables in this macro is racy. We can't use atomic_t
  * here because all these variables are exported to debugfs. Some of them even
  * writeable. This is also the reason why a lock won't help much. But anyway,
  * the races are no big deal. Here is why:
  *
  *   error_count: the addition is racy, but the worst thing that can happen is
  *                that we don't count some errors
  *   show_num_errors: the subtraction is racy. Also no big deal because in
  *                    worst case this will result in one warning more in the
  *                    system log than the user configured. This variable is
  *                    writeable via debugfs.
  */
 static inline void dump_entry_trace(struct dma_debug_entry *entry)
 {
 #ifdef CONFIG_STACKTRACE
     if (entry) {
         pr_warn("Mapped at:\n");
         stack_trace_print(entry->stack_entries, entry->stack_len, 0);
     }
 #endif
 }
 
 static bool driver_filter(struct device *dev)
 {
     struct device_driver *drv;
     unsigned long flags;
     bool ret;
 
     /* driver filter off */
     if (likely(!current_driver_name[0]))
         return true;
 
     /* driver filter on and initialized */
     if (current_driver && dev && dev->driver == current_driver)
         return true;
 
     /* driver filter on, but we can't filter on a NULL device... */
     if (!dev)
         return false;
 
     if (current_driver || !current_driver_name[0])
         return false;
 
     /* driver filter on but not yet initialized */
     drv = dev->driver;
     if (!drv)
         return false;
 
     /* lock to protect against change of current_driver_name */
     read_lock_irqsave(&driver_name_lock, flags);
 
     ret = false;
     if (drv->name &&
         strncmp(current_driver_name, drv->name, NAME_MAX_LEN - 1) == 0) {
         current_driver = drv;
         ret = true;
     }
 
     read_unlock_irqrestore(&driver_name_lock, flags);
 
     return ret;
 }
 
 #define err_printk(dev, entry, format, arg...) do {         \
         error_count += 1;                   \
         if (driver_filter(dev) &&               \
             (show_all_errors || show_num_errors > 0)) {     \
             WARN(1, pr_fmt("%s %s: ") format,       \
                  dev ? dev_driver_string(dev) : "NULL", \
                  dev ? dev_name(dev) : "NULL", ## arg); \
             dump_entry_trace(entry);            \
         }                           \
         if (!show_all_errors && show_num_errors > 0)        \
             show_num_errors -= 1;               \
     } while (0);
 
 /*
  * Hash related functions
  *
  * Every DMA-API request is saved into a struct dma_debug_entry. To
  * have quick access to these structs they are stored into a hash.
  */
 static int hash_fn(struct dma_debug_entry *entry)
 {
     /*
      * Hash function is based on the dma address.
      * We use bits 20-27 here as the index into the hash
      */
     return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK;
 }
 
 /*
  * Request exclusive access to a hash bucket for a given dma_debug_entry.
  */
 static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
                        unsigned long *flags)
     __acquires(&dma_entry_hash[idx].lock)
 {
     int idx = hash_fn(entry);
     unsigned long __flags;
 
     spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags);
     *flags = __flags;
     return &dma_entry_hash[idx];
 }
 
 /*
  * Give up exclusive access to the hash bucket
  */
 static void put_hash_bucket(struct hash_bucket *bucket,
                 unsigned long flags)
     __releases(&bucket->lock)
 {
     spin_unlock_irqrestore(&bucket->lock, flags);
 }
 
 static bool exact_match(struct dma_debug_entry *a, struct dma_debug_entry *b)
 {
     return ((a->dev_addr == b->dev_addr) &&
         (a->dev == b->dev)) ? true : false;
 }
 
 static bool containing_match(struct dma_debug_entry *a,
                  struct dma_debug_entry *b)
 {
     if (a->dev != b->dev)
         return false;
 
     if ((b->dev_addr <= a->dev_addr) &&
         ((b->dev_addr + b->size) >= (a->dev_addr + a->size)))
         return true;
 
     return false;
 }
 
 /*
  * Search a given entry in the hash bucket list
  */
 static struct dma_debug_entry *__hash_bucket_find(struct hash_bucket *bucket,
                           struct dma_debug_entry *ref,
                           match_fn match)
 {
     struct dma_debug_entry *entry, *ret = NULL;
     int matches = 0, match_lvl, last_lvl = -1;
 
     list_for_each_entry(entry, &bucket->list, list) {
         if (!match(ref, entry))
             continue;
 
         /*
          * Some drivers map the same physical address multiple
          * times. Without a hardware IOMMU this results in the
          * same device addresses being put into the dma-debug
          * hash multiple times too. This can result in false
          * positives being reported. Therefore we implement a
          * best-fit algorithm here which returns the entry from
          * the hash which fits best to the reference value
          * instead of the first-fit.
          */
         matches += 1;
         match_lvl = 0;
         entry->size         == ref->size         ? ++match_lvl : 0;
         entry->type         == ref->type         ? ++match_lvl : 0;
         entry->direction    == ref->direction    ? ++match_lvl : 0;
         entry->sg_call_ents == ref->sg_call_ents ? ++match_lvl : 0;
 
         if (match_lvl == 4) {
             /* perfect-fit - return the result */
             return entry;
         } else if (match_lvl > last_lvl) {
             /*
              * We found an entry that fits better then the
              * previous one or it is the 1st match.
              */
             last_lvl = match_lvl;
             ret      = entry;
         }
     }
 
     /*
      * If we have multiple matches but no perfect-fit, just return
      * NULL.
      */
     ret = (matches == 1) ? ret : NULL;
 
     return ret;
 }
 
 static struct dma_debug_entry *bucket_find_exact(struct hash_bucket *bucket,
                          struct dma_debug_entry *ref)
 {
     return __hash_bucket_find(bucket, ref, exact_match);
 }
 
 static struct dma_debug_entry *bucket_find_contain(struct hash_bucket **bucket,
                            struct dma_debug_entry *ref,
                            unsigned long *flags)
 {
 
     struct dma_debug_entry *entry, index = *ref;
     int limit = min(HASH_SIZE, (index.dev_addr >> HASH_FN_SHIFT) + 1);
 
     for (int i = 0; i < limit; i++) {
         entry = __hash_bucket_find(*bucket, ref, containing_match);
 
         if (entry)
             return entry;
 
         /*
          * Nothing found, go back a hash bucket
          */
         put_hash_bucket(*bucket, *flags);
         index.dev_addr -= (1 << HASH_FN_SHIFT);
         *bucket = get_hash_bucket(&index, flags);
     }
 
     return NULL;
 }
 
 /*
  * Add an entry to a hash bucket
  */
 static void hash_bucket_add(struct hash_bucket *bucket,
                 struct dma_debug_entry *entry)
 {
     list_add_tail(&entry->list, &bucket->list);
 }
 
 /*
  * Remove entry from a hash bucket list
  */
 static void hash_bucket_del(struct dma_debug_entry *entry)
 {
     list_del(&entry->list);
 }
 
 static unsigned long long phys_addr(struct dma_debug_entry *entry)
 {
     if (entry->type == dma_debug_resource)
         return __pfn_to_phys(entry->pfn) + entry->offset;
 
     return page_to_phys(pfn_to_page(entry->pfn)) + entry->offset;
 }
 
 /*
  * Dump mapping entries for debugging purposes
  */
 void debug_dma_dump_mappings(struct device *dev)
 {
     int idx;
 
     for (idx = 0; idx < HASH_SIZE; idx++) {
         struct hash_bucket *bucket = &dma_entry_hash[idx];
         struct dma_debug_entry *entry;
         unsigned long flags;
 
         spin_lock_irqsave(&bucket->lock, flags);
 
         list_for_each_entry(entry, &bucket->list, list) {
             if (!dev || dev == entry->dev) {
                 dev_info(entry->dev,
                      "%s idx %d P=%Lx N=%lx D=%Lx L=%Lx %s %s\n",
                      type2name[entry->type], idx,
                      phys_addr(entry), entry->pfn,
                      entry->dev_addr, entry->size,
                      dir2name[entry->direction],
                      maperr2str[entry->map_err_type]);
             }
         }
 
         spin_unlock_irqrestore(&bucket->lock, flags);
         cond_resched();
     }
 }
 
 /*
  * For each mapping (initial cacheline in the case of
  * dma_alloc_coherent/dma_map_page, initial cacheline in each page of a
  * scatterlist, or the cacheline specified in dma_map_single) insert
  * into this tree using the cacheline as the key. At
  * dma_unmap_{single|sg|page} or dma_free_coherent delete the entry.  If
  * the entry already exists at insertion time add a tag as a reference
  * count for the overlapping mappings.  For now, the overlap tracking
  * just ensures that 'unmaps' balance 'maps' before marking the
  * cacheline idle, but we should also be flagging overlaps as an API
  * violation.
  *
  * Memory usage is mostly constrained by the maximum number of available
  * dma-debug entries in that we need a free dma_debug_entry before
  * inserting into the tree.  In the case of dma_map_page and
  * dma_alloc_coherent there is only one dma_debug_entry and one
  * dma_active_cacheline entry to track per event.  dma_map_sg(), on the
  * other hand, consumes a single dma_debug_entry, but inserts 'nents'
  * entries into the tree.
  */
 static RADIX_TREE(dma_active_cacheline, GFP_ATOMIC);
 static DEFINE_SPINLOCK(radix_lock);
 #define ACTIVE_CACHELINE_MAX_OVERLAP ((1 << RADIX_TREE_MAX_TAGS) - 1)
 #define CACHELINE_PER_PAGE_SHIFT (PAGE_SHIFT - L1_CACHE_SHIFT)
 #define CACHELINES_PER_PAGE (1 << CACHELINE_PER_PAGE_SHIFT)
 
 static phys_addr_t to_cacheline_number(struct dma_debug_entry *entry)
 {
     return (entry->pfn << CACHELINE_PER_PAGE_SHIFT) +
         (entry->offset >> L1_CACHE_SHIFT);
 }
 
 static int active_cacheline_read_overlap(phys_addr_t cln)
 {
     int overlap = 0, i;
 
     for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--)
         if (radix_tree_tag_get(&dma_active_cacheline, cln, i))
             overlap |= 1 << i;
     return overlap;
 }
 
 static int active_cacheline_set_overlap(phys_addr_t cln, int overlap)
 {
     int i;
 
     if (overlap > ACTIVE_CACHELINE_MAX_OVERLAP || overlap < 0)
         return overlap;
 
     for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--)
         if (overlap & 1 << i)
             radix_tree_tag_set(&dma_active_cacheline, cln, i);
         else
             radix_tree_tag_clear(&dma_active_cacheline, cln, i);
 
     return overlap;
 }
 
 static void active_cacheline_inc_overlap(phys_addr_t cln)
 {
     int overlap = active_cacheline_read_overlap(cln);
 
     overlap = active_cacheline_set_overlap(cln, ++overlap);
 
     /* If we overflowed the overlap counter then we're potentially
      * leaking dma-mappings.
      */
     WARN_ONCE(overlap > ACTIVE_CACHELINE_MAX_OVERLAP,
           pr_fmt("exceeded %d overlapping mappings of cacheline %pa\n"),
           ACTIVE_CACHELINE_MAX_OVERLAP, &cln);
 }
 
 static int active_cacheline_dec_overlap(phys_addr_t cln)
 {
     int overlap = active_cacheline_read_overlap(cln);
 
     return active_cacheline_set_overlap(cln, --overlap);
 }
 
 static int active_cacheline_insert(struct dma_debug_entry *entry)
 {
     phys_addr_t cln = to_cacheline_number(entry);
     unsigned long flags;
     int rc;
 
     /* If the device is not writing memory then we don't have any
      * concerns about the cpu consuming stale data.  This mitigates
      * legitimate usages of overlapping mappings.
      */
     if (entry->direction == DMA_TO_DEVICE)
         return 0;
 
     spin_lock_irqsave(&radix_lock, flags);
     rc = radix_tree_insert(&dma_active_cacheline, cln, entry);
     if (rc == -EEXIST)
         active_cacheline_inc_overlap(cln);
     spin_unlock_irqrestore(&radix_lock, flags);
 
     return rc;
 }
 
 static void active_cacheline_remove(struct dma_debug_entry *entry)
 {
     phys_addr_t cln = to_cacheline_number(entry);
     unsigned long flags;
 
     /* ...mirror the insert case */
     if (entry->direction == DMA_TO_DEVICE)
         return;
 
     spin_lock_irqsave(&radix_lock, flags);
     /* since we are counting overlaps the final put of the
      * cacheline will occur when the overlap count is 0.
      * active_cacheline_dec_overlap() returns -1 in that case
      */
     if (active_cacheline_dec_overlap(cln) < 0)
         radix_tree_delete(&dma_active_cacheline, cln);
     spin_unlock_irqrestore(&radix_lock, flags);
 }
 
 /*
  * Wrapper function for adding an entry to the hash.
  * This function takes care of locking itself.
  */
 static void add_dma_entry(struct dma_debug_entry *entry, unsigned long attrs)
 {
     struct hash_bucket *bucket;
     unsigned long flags;
     int rc;
 
     bucket = get_hash_bucket(entry, &flags);
     hash_bucket_add(bucket, entry);
     put_hash_bucket(bucket, flags);
 
     rc = active_cacheline_insert(entry);
     if (rc == -ENOMEM) {
         pr_err_once("cacheline tracking ENOMEM, dma-debug disabled\n");
         global_disable = true;
     } else if (rc == -EEXIST && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
         err_printk(entry->dev, entry,
             "cacheline tracking EEXIST, overlapping mappings aren't supported\n");
     }
 }
 
 static int dma_debug_create_entries(gfp_t gfp)
 {
     struct dma_debug_entry *entry;
     int i;
 
     entry = (void *)get_zeroed_page(gfp);
     if (!entry)
         return -ENOMEM;
 
     for (i = 0; i < DMA_DEBUG_DYNAMIC_ENTRIES; i++)
         list_add_tail(&entry[i].list, &free_entries);
 
     num_free_entries += DMA_DEBUG_DYNAMIC_ENTRIES;
     nr_total_entries += DMA_DEBUG_DYNAMIC_ENTRIES;
 
     return 0;
 }
 
 static struct dma_debug_entry *__dma_entry_alloc(void)
 {
     struct dma_debug_entry *entry;
 
     entry = list_entry(free_entries.next, struct dma_debug_entry, list);
     list_del(&entry->list);
     memset(entry, 0, sizeof(*entry));
 
     num_free_entries -= 1;
     if (num_free_entries < min_free_entries)
         min_free_entries = num_free_entries;
 
     return entry;
 }
 
 static void __dma_entry_alloc_check_leak(void)
 {
     u32 tmp = nr_total_entries % nr_prealloc_entries;
 
     /* Shout each time we tick over some multiple of the initial pool */
     if (tmp < DMA_DEBUG_DYNAMIC_ENTRIES) {
         pr_info("dma_debug_entry pool grown to %u (%u00%%)\n",
             nr_total_entries,
             (nr_total_entries / nr_prealloc_entries));
     }
 }
 
 /* struct dma_entry allocator
  *
  * The next two functions implement the allocator for
  * struct dma_debug_entries.
  */
 static struct dma_debug_entry *dma_entry_alloc(void)
 {
     struct dma_debug_entry *entry;
     unsigned long flags;
 
     spin_lock_irqsave(&free_entries_lock, flags);
     if (num_free_entries == 0) {
         if (dma_debug_create_entries(GFP_ATOMIC)) {
             global_disable = true;
             spin_unlock_irqrestore(&free_entries_lock, flags);
             pr_err("debugging out of memory - disabling\n");
             return NULL;
         }
         __dma_entry_alloc_check_leak();
     }
 
     entry = __dma_entry_alloc();
 
     spin_unlock_irqrestore(&free_entries_lock, flags);
 
 #ifdef CONFIG_STACKTRACE
     entry->stack_len = stack_trace_save(entry->stack_entries,
                         ARRAY_SIZE(entry->stack_entries),
                         1);
 #endif
     return entry;
 }
 
 static void dma_entry_free(struct dma_debug_entry *entry)
 {
     unsigned long flags;
 
     active_cacheline_remove(entry);
 
     /*
      * add to beginning of the list - this way the entries are
      * more likely cache hot when they are reallocated.
      */
     spin_lock_irqsave(&free_entries_lock, flags);
     list_add(&entry->list, &free_entries);
     num_free_entries += 1;
     spin_unlock_irqrestore(&free_entries_lock, flags);
 }
 
 /*
  * DMA-API debugging init code
  *
  * The init code does two things:
  *   1. Initialize core data structures
  *   2. Preallocate a given number of dma_debug_entry structs
  */
 
 static ssize_t filter_read(struct file *file, char __user *user_buf,
                size_t count, loff_t *ppos)
 {
     char buf[NAME_MAX_LEN + 1];
     unsigned long flags;
     int len;
 
     if (!current_driver_name[0])
         return 0;
 
     /*
      * We can't copy to userspace directly because current_driver_name can
      * only be read under the driver_name_lock with irqs disabled. So
      * create a temporary copy first.
      */
     read_lock_irqsave(&driver_name_lock, flags);
     len = scnprintf(buf, NAME_MAX_LEN + 1, "%s\n", current_driver_name);
     read_unlock_irqrestore(&driver_name_lock, flags);
 
     return simple_read_from_buffer(user_buf, count, ppos, buf, len);
 }
 
 static ssize_t filter_write(struct file *file, const char __user *userbuf,
                 size_t count, loff_t *ppos)
 {
     char buf[NAME_MAX_LEN];
     unsigned long flags;
     size_t len;
     int i;
 
     /*
      * We can't copy from userspace directly. Access to
      * current_driver_name is protected with a write_lock with irqs
      * disabled. Since copy_from_user can fault and may sleep we
      * need to copy to temporary buffer first
      */
     len = min(count, (size_t)(NAME_MAX_LEN - 1));
     if (copy_from_user(buf, userbuf, len))
         return -EFAULT;
 
     buf[len] = 0;
 
     write_lock_irqsave(&driver_name_lock, flags);
 
     /*
      * Now handle the string we got from userspace very carefully.
      * The rules are:
      *         - only use the first token we got
      *         - token delimiter is everything looking like a space
      *           character (' ', '\n', '\t' ...)
      *
      */
     if (!isalnum(buf[0])) {
         /*
          * If the first character userspace gave us is not
          * alphanumerical then assume the filter should be
          * switched off.
          */
         if (current_driver_name[0])
             pr_info("switching off dma-debug driver filter\n");
         current_driver_name[0] = 0;
         current_driver = NULL;
         goto out_unlock;
     }
 
     /*
      * Now parse out the first token and use it as the name for the
      * driver to filter for.
      */
     for (i = 0; i < NAME_MAX_LEN - 1; ++i) {
         current_driver_name[i] = buf[i];
         if (isspace(buf[i]) || buf[i] == ' ' || buf[i] == 0)
             break;
     }
     current_driver_name[i] = 0;
     current_driver = NULL;
 
     pr_info("enable driver filter for driver [%s]\n",
         current_driver_name);
 
 out_unlock:
     write_unlock_irqrestore(&driver_name_lock, flags);
 
     return count;
 }
 
 static const struct file_operations filter_fops = {
     .read  = filter_read,
     .write = filter_write,
     .llseek = default_llseek,
 };
 
 static int dump_show(struct seq_file *seq, void *v)
 {
     int idx;
 
     for (idx = 0; idx < HASH_SIZE; idx++) {
         struct hash_bucket *bucket = &dma_entry_hash[idx];
         struct dma_debug_entry *entry;
         unsigned long flags;
 
         spin_lock_irqsave(&bucket->lock, flags);
         list_for_each_entry(entry, &bucket->list, list) {
             seq_printf(seq,
                    "%s %s %s idx %d P=%llx N=%lx D=%llx L=%llx %s %s\n",
                    dev_name(entry->dev),
                    dev_driver_string(entry->dev),
                    type2name[entry->type], idx,
                    phys_addr(entry), entry->pfn,
                    entry->dev_addr, entry->size,
                    dir2name[entry->direction],
                    maperr2str[entry->map_err_type]);
         }
         spin_unlock_irqrestore(&bucket->lock, flags);
     }
     return 0;
 }
 DEFINE_SHOW_ATTRIBUTE(dump);
 
 static int __init dma_debug_fs_init(void)
 {
     struct dentry *dentry = debugfs_create_dir("dma-api", NULL);
 
     debugfs_create_bool("disabled", 0444, dentry, &global_disable);
     debugfs_create_u32("error_count", 0444, dentry, &error_count);
     debugfs_create_u32("all_errors", 0644, dentry, &show_all_errors);
     debugfs_create_u32("num_errors", 0644, dentry, &show_num_errors);
     debugfs_create_u32("num_free_entries", 0444, dentry, &num_free_entries);
     debugfs_create_u32("min_free_entries", 0444, dentry, &min_free_entries);
     debugfs_create_u32("nr_total_entries", 0444, dentry, &nr_total_entries);
     debugfs_create_file("driver_filter", 0644, dentry, NULL, &filter_fops);
     debugfs_create_file("dump", 0444, dentry, NULL, &dump_fops);
 
     return 0;
 }
 core_initcall_sync(dma_debug_fs_init);
 
 static int device_dma_allocations(struct device *dev, struct dma_debug_entry **out_entry)
 {
     struct dma_debug_entry *entry;
     unsigned long flags;
     int count = 0, i;
 
     for (i = 0; i < HASH_SIZE; ++i) {
         spin_lock_irqsave(&dma_entry_hash[i].lock, flags);
         list_for_each_entry(entry, &dma_entry_hash[i].list, list) {
             if (entry->dev == dev) {
                 count += 1;
                 *out_entry = entry;
             }
         }
         spin_unlock_irqrestore(&dma_entry_hash[i].lock, flags);
     }
 
     return count;
 }
 
 static int dma_debug_device_change(struct notifier_block *nb, unsigned long action, void *data)
 {
     struct device *dev = data;
     struct dma_debug_entry *entry;
     int count;
 
     if (dma_debug_disabled())
         return 0;
 
     switch (action) {
     case BUS_NOTIFY_UNBOUND_DRIVER:
         count = device_dma_allocations(dev, &entry);
         if (count == 0)
             break;
         err_printk(dev, entry, "device driver has pending "
                 "DMA allocations while released from device "
                 "[count=%d]\n"
                 "One of leaked entries details: "
                 "[device address=0x%016llx] [size=%llu bytes] "
                 "[mapped with %s] [mapped as %s]\n",
             count, entry->dev_addr, entry->size,
             dir2name[entry->direction], type2name[entry->type]);
         break;
     default:
         break;
     }
 
     return 0;
 }
 
 void dma_debug_add_bus(struct bus_type *bus)
 {
     struct notifier_block *nb;
 
     if (dma_debug_disabled())
         return;
 
     nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
     if (nb == NULL) {
         pr_err("dma_debug_add_bus: out of memory\n");
         return;
     }
 
     nb->notifier_call = dma_debug_device_change;
 
     bus_register_notifier(bus, nb);
 }
 
 static int dma_debug_init(void)
 {
     int i, nr_pages;
 
     /* Do not use dma_debug_initialized here, since we really want to be
      * called to set dma_debug_initialized
      */
     if (global_disable)
         return 0;
 
     for (i = 0; i < HASH_SIZE; ++i) {
         INIT_LIST_HEAD(&dma_entry_hash[i].list);
         spin_lock_init(&dma_entry_hash[i].lock);
     }
 
     nr_pages = DIV_ROUND_UP(nr_prealloc_entries, DMA_DEBUG_DYNAMIC_ENTRIES);
     for (i = 0; i < nr_pages; ++i)
         dma_debug_create_entries(GFP_KERNEL);
     if (num_free_entries >= nr_prealloc_entries) {
         pr_info("preallocated %d debug entries\n", nr_total_entries);
     } else if (num_free_entries > 0) {
         pr_warn("%d debug entries requested but only %d allocated\n",
             nr_prealloc_entries, nr_total_entries);
     } else {
         pr_err("debugging out of memory error - disabled\n");
         global_disable = true;
 
         return 0;
     }
     min_free_entries = num_free_entries;
 
     dma_debug_initialized = true;
 
     pr_info("debugging enabled by kernel config\n");
     return 0;
 }
 core_initcall(dma_debug_init);
 
 static __init int dma_debug_cmdline(char *str)
 {
     if (!str)
         return -EINVAL;
 
     if (strncmp(str, "off", 3) == 0) {
         pr_info("debugging disabled on kernel command line\n");
         global_disable = true;
     }
 
     return 1;
 }
 
 static __init int dma_debug_entries_cmdline(char *str)
 {
     if (!str)
         return -EINVAL;
     if (!get_option(&str, &nr_prealloc_entries))
         nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;
     return 1;
 }
 
 __setup("dma_debug=", dma_debug_cmdline);
 __setup("dma_debug_entries=", dma_debug_entries_cmdline);
 
 static void check_unmap(struct dma_debug_entry *ref)
 {
     struct dma_debug_entry *entry;
     struct hash_bucket *bucket;
     unsigned long flags;
 
     bucket = get_hash_bucket(ref, &flags);
     entry = bucket_find_exact(bucket, ref);
 
     if (!entry) {
         /* must drop lock before calling dma_mapping_error */
         put_hash_bucket(bucket, flags);
 
         if (dma_mapping_error(ref->dev, ref->dev_addr)) {
             err_printk(ref->dev, NULL,
                    "device driver tries to free an "
                    "invalid DMA memory address\n");
         } else {
             err_printk(ref->dev, NULL,
                    "device driver tries to free DMA "
                    "memory it has not allocated [device "
                    "address=0x%016llx] [size=%llu bytes]\n",
                    ref->dev_addr, ref->size);
         }
         return;
     }
 
     if (ref->size != entry->size) {
         err_printk(ref->dev, entry, "device driver frees "
                "DMA memory with different size "
                "[device address=0x%016llx] [map size=%llu bytes] "
                "[unmap size=%llu bytes]\n",
                ref->dev_addr, entry->size, ref->size);
     }
 
     if (ref->type != entry->type) {
         err_printk(ref->dev, entry, "device driver frees "
                "DMA memory with wrong function "
                "[device address=0x%016llx] [size=%llu bytes] "
                "[mapped as %s] [unmapped as %s]\n",
                ref->dev_addr, ref->size,
                type2name[entry->type], type2name[ref->type]);
     } else if ((entry->type == dma_debug_coherent) &&
            (phys_addr(ref) != phys_addr(entry))) {
         err_printk(ref->dev, entry, "device driver frees "
                "DMA memory with different CPU address "
                "[device address=0x%016llx] [size=%llu bytes] "
                "[cpu alloc address=0x%016llx] "
                "[cpu free address=0x%016llx]",
                ref->dev_addr, ref->size,
                phys_addr(entry),
                phys_addr(ref));
     }
 
     if (ref->sg_call_ents && ref->type == dma_debug_sg &&
         ref->sg_call_ents != entry->sg_call_ents) {
         err_printk(ref->dev, entry, "device driver frees "
                "DMA sg list with different entry count "
                "[map count=%d] [unmap count=%d]\n",
                entry->sg_call_ents, ref->sg_call_ents);
     }
 
     /*
      * This may be no bug in reality - but most implementations of the
      * DMA API don't handle this properly, so check for it here
      */
     if (ref->direction != entry->direction) {
         err_printk(ref->dev, entry, "device driver frees "
                "DMA memory with different direction "
                "[device address=0x%016llx] [size=%llu bytes] "
                "[mapped with %s] [unmapped with %s]\n",
                ref->dev_addr, ref->size,
                dir2name[entry->direction],
                dir2name[ref->direction]);
     }
 
     /*
      * Drivers should use dma_mapping_error() to check the returned
      * addresses of dma_map_single() and dma_map_page().
      * If not, print this warning message. See Documentation/core-api/dma-api.rst.
      */
     if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
         err_printk(ref->dev, entry,
                "device driver failed to check map error"
                "[device address=0x%016llx] [size=%llu bytes] "
                "[mapped as %s]",
                ref->dev_addr, ref->size,
                type2name[entry->type]);
     }
 
     hash_bucket_del(entry);
     dma_entry_free(entry);
 
     put_hash_bucket(bucket, flags);
 }
 
 static void check_for_stack(struct device *dev,
                 struct page *page, size_t offset)
 {
     void *addr;
     struct vm_struct *stack_vm_area = task_stack_vm_area(current);
 
     if (!stack_vm_area) {
         /* Stack is direct-mapped. */
         if (PageHighMem(page))
             return;
         addr = page_address(page) + offset;
         if (object_is_on_stack(addr))
             err_printk(dev, NULL, "device driver maps memory from stack [addr=%p]\n", addr);
     } else {
         /* Stack is vmalloced. */
         int i;
 
         for (i = 0; i < stack_vm_area->nr_pages; i++) {
             if (page != stack_vm_area->pages[i])
                 continue;
 
             addr = (u8 *)current->stack + i * PAGE_SIZE + offset;
             err_printk(dev, NULL, "device driver maps memory from stack [probable addr=%p]\n", addr);
             break;
         }
     }
 }
 
 static void check_for_illegal_area(struct device *dev, void *addr, unsigned long len)
 {
     if (memory_intersects(_stext, _etext, addr, len) ||
         memory_intersects(__start_rodata, __end_rodata, addr, len))
         err_printk(dev, NULL, "device driver maps memory from kernel text or rodata [addr=%p] [len=%lu]\n", addr, len);
 }
 
 static void check_sync(struct device *dev,
                struct dma_debug_entry *ref,
                bool to_cpu)
 {
     struct dma_debug_entry *entry;
     struct hash_bucket *bucket;
     unsigned long flags;
 
     bucket = get_hash_bucket(ref, &flags);
 
     entry = bucket_find_contain(&bucket, ref, &flags);
 
     if (!entry) {
         err_printk(dev, NULL, "device driver tries "
                 "to sync DMA memory it has not allocated "
                 "[device address=0x%016llx] [size=%llu bytes]\n",
                 (unsigned long long)ref->dev_addr, ref->size);
         goto out;
     }
 
     if (ref->size > entry->size) {
         err_printk(dev, entry, "device driver syncs"
                 " DMA memory outside allocated range "
                 "[device address=0x%016llx] "
                 "[allocation size=%llu bytes] "
                 "[sync offset+size=%llu]\n",
                 entry->dev_addr, entry->size,
                 ref->size);
     }
 
     if (entry->direction == DMA_BIDIRECTIONAL)
         goto out;
 
     if (ref->direction != entry->direction) {
         err_printk(dev, entry, "device driver syncs "
                 "DMA memory with different direction "
                 "[device address=0x%016llx] [size=%llu bytes] "
                 "[mapped with %s] [synced with %s]\n",
                 (unsigned long long)ref->dev_addr, entry->size,
                 dir2name[entry->direction],
                 dir2name[ref->direction]);
     }
 
     if (to_cpu && !(entry->direction == DMA_FROM_DEVICE) &&
               !(ref->direction == DMA_TO_DEVICE))
         err_printk(dev, entry, "device driver syncs "
                 "device read-only DMA memory for cpu "
                 "[device address=0x%016llx] [size=%llu bytes] "
                 "[mapped with %s] [synced with %s]\n",
                 (unsigned long long)ref->dev_addr, entry->size,
                 dir2name[entry->direction],
                 dir2name[ref->direction]);
 
     if (!to_cpu && !(entry->direction == DMA_TO_DEVICE) &&
                !(ref->direction == DMA_FROM_DEVICE))
         err_printk(dev, entry, "device driver syncs "
                 "device write-only DMA memory to device "
                 "[device address=0x%016llx] [size=%llu bytes] "
                 "[mapped with %s] [synced with %s]\n",
                 (unsigned long long)ref->dev_addr, entry->size,
                 dir2name[entry->direction],
                 dir2name[ref->direction]);
 
     if (ref->sg_call_ents && ref->type == dma_debug_sg &&
         ref->sg_call_ents != entry->sg_call_ents) {
         err_printk(ref->dev, entry, "device driver syncs "
                "DMA sg list with different entry count "
                "[map count=%d] [sync count=%d]\n",
                entry->sg_call_ents, ref->sg_call_ents);
     }
 
 out:
     put_hash_bucket(bucket, flags);
 }
 
 static void check_sg_segment(struct device *dev, struct scatterlist *sg)
 {
 #ifdef CONFIG_DMA_API_DEBUG_SG
     unsigned int max_seg = dma_get_max_seg_size(dev);
     u64 start, end, boundary = dma_get_seg_boundary(dev);
 
     /*
      * Either the driver forgot to set dma_parms appropriately, or
      * whoever generated the list forgot to check them.
      */
     if (sg->length > max_seg)
         err_printk(dev, NULL, "mapping sg segment longer than device claims to support [len=%u] [max=%u]\n",
                sg->length, max_seg);
     /*
      * In some cases this could potentially be the DMA API
      * implementation's fault, but it would usually imply that
      * the scatterlist was built inappropriately to begin with.
      */
     start = sg_dma_address(sg);
     end = start + sg_dma_len(sg) - 1;
     if ((start ^ end) & ~boundary)
         err_printk(dev, NULL, "mapping sg segment across boundary [start=0x%016llx] [end=0x%016llx] [boundary=0x%016llx]\n",
                start, end, boundary);
 #endif
 }
 
 void debug_dma_map_single(struct device *dev, const void *addr,
                 unsigned long len)
 {
     if (unlikely(dma_debug_disabled()))
         return;
 
     if (!virt_addr_valid(addr))
         err_printk(dev, NULL, "device driver maps memory from invalid area [addr=%p] [len=%lu]\n",
                addr, len);
 
     if (is_vmalloc_addr(addr))
         err_printk(dev, NULL, "device driver maps memory from vmalloc area [addr=%p] [len=%lu]\n",
                addr, len);
 }
 EXPORT_SYMBOL(debug_dma_map_single);
 
 void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
             size_t size, int direction, dma_addr_t dma_addr,
             unsigned long attrs)
 {
     struct dma_debug_entry *entry;
 
     if (unlikely(dma_debug_disabled()))
         return;
 
     if (dma_mapping_error(dev, dma_addr))
         return;
 
     entry = dma_entry_alloc();
     if (!entry)
         return;
 
     entry->dev       = dev;
     entry->type      = dma_debug_single;
     entry->pfn   = page_to_pfn(page);
     entry->offset    = offset;
     entry->dev_addr  = dma_addr;
     entry->size      = size;
     entry->direction = direction;
     entry->map_err_type = MAP_ERR_NOT_CHECKED;
 
     check_for_stack(dev, page, offset);
 
     if (!PageHighMem(page)) {
         void *addr = page_address(page) + offset;
 
         check_for_illegal_area(dev, addr, size);
     }
 
     add_dma_entry(entry, attrs);
 }
 
 void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
     struct dma_debug_entry ref;
     struct dma_debug_entry *entry;
     struct hash_bucket *bucket;
     unsigned long flags;
 
     if (unlikely(dma_debug_disabled()))
         return;
 
     ref.dev = dev;
     ref.dev_addr = dma_addr;
     bucket = get_hash_bucket(&ref, &flags);
 
     list_for_each_entry(entry, &bucket->list, list) {
         if (!exact_match(&ref, entry))
             continue;
 
         /*
          * The same physical address can be mapped multiple
          * times. Without a hardware IOMMU this results in the
          * same device addresses being put into the dma-debug
          * hash multiple times too. This can result in false
          * positives being reported. Therefore we implement a
          * best-fit algorithm here which updates the first entry
          * from the hash which fits the reference value and is
          * not currently listed as being checked.
          */
         if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
             entry->map_err_type = MAP_ERR_CHECKED;
             break;
         }
     }
 
     put_hash_bucket(bucket, flags);
 }
 EXPORT_SYMBOL(debug_dma_mapping_error);
 
 void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
               size_t size, int direction)
 {
     struct dma_debug_entry ref = {
         .type           = dma_debug_single,
         .dev            = dev,
         .dev_addr       = addr,
         .size           = size,
         .direction      = direction,
     };
 
     if (unlikely(dma_debug_disabled()))
         return;
     check_unmap(&ref);
 }
 
 void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
               int nents, int mapped_ents, int direction,
               unsigned long attrs)
 {
     struct dma_debug_entry *entry;
     struct scatterlist *s;
     int i;
 
     if (unlikely(dma_debug_disabled()))
         return;
 
     for_each_sg(sg, s, nents, i) {
         check_for_stack(dev, sg_page(s), s->offset);
         if (!PageHighMem(sg_page(s)))
             check_for_illegal_area(dev, sg_virt(s), s->length);
     }
 
     for_each_sg(sg, s, mapped_ents, i) {
         entry = dma_entry_alloc();
         if (!entry)
             return;
 
         entry->type           = dma_debug_sg;
         entry->dev            = dev;
         entry->pfn        = page_to_pfn(sg_page(s));
         entry->offset         = s->offset;
         entry->size           = sg_dma_len(s);
         entry->dev_addr       = sg_dma_address(s);
         entry->direction      = direction;
         entry->sg_call_ents   = nents;
         entry->sg_mapped_ents = mapped_ents;
 
         check_sg_segment(dev, s);
 
         add_dma_entry(entry, attrs);
     }
 }
 
 static int get_nr_mapped_entries(struct device *dev,
                  struct dma_debug_entry *ref)
 {
     struct dma_debug_entry *entry;
     struct hash_bucket *bucket;
     unsigned long flags;
     int mapped_ents;
 
     bucket       = get_hash_bucket(ref, &flags);
     entry        = bucket_find_exact(bucket, ref);
     mapped_ents  = 0;
 
     if (entry)
         mapped_ents = entry->sg_mapped_ents;
     put_hash_bucket(bucket, flags);
 
     return mapped_ents;
 }
 
 void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
             int nelems, int dir)
 {
     struct scatterlist *s;
     int mapped_ents = 0, i;
 
     if (unlikely(dma_debug_disabled()))
         return;
 
     for_each_sg(sglist, s, nelems, i) {
 
         struct dma_debug_entry ref = {
             .type           = dma_debug_sg,
             .dev            = dev,
             .pfn        = page_to_pfn(sg_page(s)),
             .offset     = s->offset,
             .dev_addr       = sg_dma_address(s),
             .size           = sg_dma_len(s),
             .direction      = dir,
             .sg_call_ents   = nelems,
         };
 
         if (mapped_ents && i >= mapped_ents)
             break;
 
         if (!i)
             mapped_ents = get_nr_mapped_entries(dev, &ref);
 
         check_unmap(&ref);
     }
 }
 
 void debug_dma_alloc_coherent(struct device *dev, size_t size,
                   dma_addr_t dma_addr, void *virt,
                   unsigned long attrs)
 {
     struct dma_debug_entry *entry;
 
     if (unlikely(dma_debug_disabled()))
         return;
 
     if (unlikely(virt == NULL))
         return;
 
     /* handle vmalloc and linear addresses */
     if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt))
         return;
 
     entry = dma_entry_alloc();
     if (!entry)
         return;
 
     entry->type      = dma_debug_coherent;
     entry->dev       = dev;
     entry->offset    = offset_in_page(virt);
     entry->size      = size;
     entry->dev_addr  = dma_addr;
     entry->direction = DMA_BIDIRECTIONAL;
 
     if (is_vmalloc_addr(virt))
         entry->pfn = vmalloc_to_pfn(virt);
     else
         entry->pfn = page_to_pfn(virt_to_page(virt));
 
     add_dma_entry(entry, attrs);
 }
 
 void debug_dma_free_coherent(struct device *dev, size_t size,
              void *virt, dma_addr_t addr)
 {
     struct dma_debug_entry ref = {
         .type           = dma_debug_coherent,
         .dev            = dev,
         .offset     = offset_in_page(virt),
         .dev_addr       = addr,
         .size           = size,
         .direction      = DMA_BIDIRECTIONAL,
     };
 
     /* handle vmalloc and linear addresses */
     if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt))
         return;
 
     if (is_vmalloc_addr(virt))
         ref.pfn = vmalloc_to_pfn(virt);
     else
         ref.pfn = page_to_pfn(virt_to_page(virt));
 
     if (unlikely(dma_debug_disabled()))
         return;
 
     check_unmap(&ref);
 }
 
 void debug_dma_map_resource(struct device *dev, phys_addr_t addr, size_t size,
                 int direction, dma_addr_t dma_addr,
                 unsigned long attrs)
 {
     struct dma_debug_entry *entry;
 
     if (unlikely(dma_debug_disabled()))
         return;
 
     entry = dma_entry_alloc();
     if (!entry)
         return;
 
     entry->type     = dma_debug_resource;
     entry->dev      = dev;
     entry->pfn      = PHYS_PFN(addr);
     entry->offset       = offset_in_page(addr);
     entry->size     = size;
     entry->dev_addr     = dma_addr;
     entry->direction    = direction;
     entry->map_err_type = MAP_ERR_NOT_CHECKED;
 
     add_dma_entry(entry, attrs);
 }
 
 void debug_dma_unmap_resource(struct device *dev, dma_addr_t dma_addr,
                   size_t size, int direction)
 {
     struct dma_debug_entry ref = {
         .type           = dma_debug_resource,
         .dev            = dev,
         .dev_addr       = dma_addr,
         .size           = size,
         .direction      = direction,
     };
 
     if (unlikely(dma_debug_disabled()))
         return;
 
     check_unmap(&ref);
 }
 
 void debug_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
                    size_t size, int direction)
 {
     struct dma_debug_entry ref;
 
     if (unlikely(dma_debug_disabled()))
         return;
 
     ref.type         = dma_debug_single;
     ref.dev          = dev;
     ref.dev_addr     = dma_handle;
     ref.size         = size;
     ref.direction    = direction;
     ref.sg_call_ents = 0;
 
     check_sync(dev, &ref, true);
 }
 
 void debug_dma_sync_single_for_device(struct device *dev,
                       dma_addr_t dma_handle, size_t size,
                       int direction)
 {
     struct dma_debug_entry ref;
 
     if (unlikely(dma_debug_disabled()))
         return;
 
     ref.type         = dma_debug_single;
     ref.dev          = dev;
     ref.dev_addr     = dma_handle;
     ref.size         = size;
     ref.direction    = direction;
     ref.sg_call_ents = 0;
 
     check_sync(dev, &ref, false);
 }
 
 void debug_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
                    int nelems, int direction)
 {
     struct scatterlist *s;
     int mapped_ents = 0, i;
 
     if (unlikely(dma_debug_disabled()))
         return;
 
     for_each_sg(sg, s, nelems, i) {
 
         struct dma_debug_entry ref = {
             .type           = dma_debug_sg,
             .dev            = dev,
             .pfn        = page_to_pfn(sg_page(s)),
             .offset     = s->offset,
             .dev_addr       = sg_dma_address(s),
             .size           = sg_dma_len(s),
             .direction      = direction,
             .sg_call_ents   = nelems,
         };
 
         if (!i)
             mapped_ents = get_nr_mapped_entries(dev, &ref);
 
         if (i >= mapped_ents)
             break;
 
         check_sync(dev, &ref, true);
     }
 }
 
 void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
                   int nelems, int direction)
 {
     struct scatterlist *s;
     int mapped_ents = 0, i;
 
     if (unlikely(dma_debug_disabled()))
         return;
 
     for_each_sg(sg, s, nelems, i) {
 
         struct dma_debug_entry ref = {
             .type           = dma_debug_sg,
             .dev            = dev,
             .pfn        = page_to_pfn(sg_page(s)),
             .offset     = s->offset,
             .dev_addr       = sg_dma_address(s),
             .size           = sg_dma_len(s),
             .direction      = direction,
             .sg_call_ents   = nelems,
         };
         if (!i)
             mapped_ents = get_nr_mapped_entries(dev, &ref);
 
         if (i >= mapped_ents)
             break;
 
         check_sync(dev, &ref, false);
     }
 }
 
 static int __init dma_debug_driver_setup(char *str)
 {
     int i;
 
     for (i = 0; i < NAME_MAX_LEN - 1; ++i, ++str) {
         current_driver_name[i] = *str;
         if (*str == 0)
             break;
     }
 
     if (current_driver_name[0])
         pr_info("enable driver filter for driver [%s]\n",
             current_driver_name);
 
 
     return 1;
 }
 __setup("dma_debug_driver=", dma_debug_driver_setup);

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