diff options
| -rw-r--r-- | Documentation/DMA-API.txt | 11 | ||||
| -rw-r--r-- | kernel/dma/debug.c | 79 |
2 files changed, 46 insertions, 44 deletions
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index 6bdb095393b0..0fcb7561af1e 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -717,8 +717,8 @@ dma-api/num_errors The number in this file shows how many dma-api/min_free_entries This read-only file can be read to get the minimum number of free dma_debug_entries the allocator has ever seen. If this value goes - down to zero the code will disable itself - because it is not longer reliable. + down to zero the code will attempt to increase + nr_total_entries to compensate. dma-api/num_free_entries The current number of free dma_debug_entries in the allocator. @@ -745,10 +745,9 @@ driver filter at boot time. The debug code will only print errors for that driver afterwards. This filter can be disabled or changed later using debugfs. When the code disables itself at runtime this is most likely because it ran -out of dma_debug_entries. These entries are preallocated at boot. The number -of preallocated entries is defined per architecture. If it is too low for you -boot with 'dma_debug_entries=<your_desired_number>' to overwrite the -architectural default. +out of dma_debug_entries and was unable to allocate more on-demand. 65536 +entries are preallocated at boot - if this is too low for you boot with +'dma_debug_entries=<your_desired_number>' to overwrite the default. :: diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c index 29486eb9d1dc..ef7c90b7a346 100644 --- a/kernel/dma/debug.c +++ b/kernel/dma/debug.c @@ -47,6 +47,8 @@ #ifndef PREALLOC_DMA_DEBUG_ENTRIES #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16) #endif +/* If the pool runs out, add this many new entries at once */ +#define DMA_DEBUG_DYNAMIC_ENTRIES 256 enum { dma_debug_single, @@ -646,6 +648,34 @@ static void add_dma_entry(struct dma_debug_entry *entry) */ } +static int dma_debug_create_entries(u32 num_entries, gfp_t gfp) +{ + struct dma_debug_entry *entry, *next_entry; + int i; + + for (i = 0; i < num_entries; ++i) { + entry = kzalloc(sizeof(*entry), gfp); + if (!entry) + goto out_err; + + list_add_tail(&entry->list, &free_entries); + } + + num_free_entries += num_entries; + nr_total_entries += num_entries; + + return 0; + +out_err: + + list_for_each_entry_safe(entry, next_entry, &free_entries, list) { + list_del(&entry->list); + kfree(entry); + } + + return -ENOMEM; +} + static struct dma_debug_entry *__dma_entry_alloc(void) { struct dma_debug_entry *entry; @@ -672,12 +702,14 @@ static struct dma_debug_entry *dma_entry_alloc(void) unsigned long flags; spin_lock_irqsave(&free_entries_lock, flags); - - if (list_empty(&free_entries)) { - global_disable = true; - spin_unlock_irqrestore(&free_entries_lock, flags); - pr_err("debugging out of memory - disabling\n"); - return NULL; + if (num_free_entries == 0) { + if (dma_debug_create_entries(DMA_DEBUG_DYNAMIC_ENTRIES, + GFP_ATOMIC)) { + global_disable = true; + spin_unlock_irqrestore(&free_entries_lock, flags); + pr_err("debugging out of memory - disabling\n"); + return NULL; + } } entry = __dma_entry_alloc(); @@ -764,36 +796,6 @@ int dma_debug_resize_entries(u32 num_entries) * 2. Preallocate a given number of dma_debug_entry structs */ -static int prealloc_memory(u32 num_entries) -{ - struct dma_debug_entry *entry, *next_entry; - int i; - - for (i = 0; i < num_entries; ++i) { - entry = kzalloc(sizeof(*entry), GFP_KERNEL); - if (!entry) - goto out_err; - - list_add_tail(&entry->list, &free_entries); - } - - num_free_entries = num_entries; - min_free_entries = num_entries; - - pr_info("preallocated %d debug entries\n", num_entries); - - return 0; - -out_err: - - list_for_each_entry_safe(entry, next_entry, &free_entries, list) { - list_del(&entry->list); - kfree(entry); - } - - return -ENOMEM; -} - static ssize_t filter_read(struct file *file, char __user *user_buf, size_t count, loff_t *ppos) { @@ -1038,14 +1040,15 @@ static int dma_debug_init(void) return 0; } - if (prealloc_memory(nr_prealloc_entries) != 0) { + if (dma_debug_create_entries(nr_prealloc_entries, GFP_KERNEL) != 0) { pr_err("debugging out of memory error - disabled\n"); global_disable = true; return 0; } - nr_total_entries = num_free_entries; + min_free_entries = num_free_entries; + pr_info("preallocated %d debug entries\n", nr_total_entries); dma_debug_initialized = true; |