diff options
| -rw-r--r-- | include/linux/swiotlb.h | 7 | ||||
| -rw-r--r-- | kernel/dma/swiotlb.c | 66 |
2 files changed, 73 insertions, 0 deletions
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index bcef10e20ea4..6dc4598d2260 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -87,6 +87,11 @@ dma_addr_t swiotlb_map(struct device *dev, phys_addr_t phys, * @for_alloc: %true if the pool is used for memory allocation * @nareas: The area number in the pool. * @area_nslabs: The slot number in the area. + * @total_used: The total number of slots in the pool that are currently used + * across all areas. Used only for calculating used_hiwater in + * debugfs. + * @used_hiwater: The high water mark for total_used. Used only for reporting + * in debugfs. */ struct io_tlb_mem { phys_addr_t start; @@ -102,6 +107,8 @@ struct io_tlb_mem { unsigned int area_nslabs; struct io_tlb_area *areas; struct io_tlb_slot *slots; + atomic_long_t total_used; + atomic_long_t used_hiwater; }; extern struct io_tlb_mem io_tlb_default_mem; diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 938c959ab19e..9bbc2802a444 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -609,6 +609,40 @@ static unsigned int wrap_area_index(struct io_tlb_mem *mem, unsigned int index) } /* + * Track the total used slots with a global atomic value in order to have + * correct information to determine the high water mark. The mem_used() + * function gives imprecise results because there's no locking across + * multiple areas. + */ +#ifdef CONFIG_DEBUG_FS +static void inc_used_and_hiwater(struct io_tlb_mem *mem, unsigned int nslots) +{ + unsigned long old_hiwater, new_used; + + new_used = atomic_long_add_return(nslots, &mem->total_used); + old_hiwater = atomic_long_read(&mem->used_hiwater); + do { + if (new_used <= old_hiwater) + break; + } while (!atomic_long_try_cmpxchg(&mem->used_hiwater, + &old_hiwater, new_used)); +} + +static void dec_used(struct io_tlb_mem *mem, unsigned int nslots) +{ + atomic_long_sub(nslots, &mem->total_used); +} + +#else /* !CONFIG_DEBUG_FS */ +static void inc_used_and_hiwater(struct io_tlb_mem *mem, unsigned int nslots) +{ +} +static void dec_used(struct io_tlb_mem *mem, unsigned int nslots) +{ +} +#endif /* CONFIG_DEBUG_FS */ + +/* * Find a suitable number of IO TLB entries size that will fit this request and * allocate a buffer from that IO TLB pool. */ @@ -702,6 +736,8 @@ found: area->index = wrap_area_index(mem, index + nslots); area->used += nslots; spin_unlock_irqrestore(&area->lock, flags); + + inc_used_and_hiwater(mem, nslots); return slot_index; } @@ -834,6 +870,8 @@ static void swiotlb_release_slots(struct device *dev, phys_addr_t tlb_addr) mem->slots[i].list = ++count; area->used -= nslots; spin_unlock_irqrestore(&area->lock, flags); + + dec_used(mem, nslots); } /* @@ -935,11 +973,37 @@ static int io_tlb_used_get(void *data, u64 *val) *val = mem_used(mem); return 0; } + +static int io_tlb_hiwater_get(void *data, u64 *val) +{ + struct io_tlb_mem *mem = data; + + *val = atomic_long_read(&mem->used_hiwater); + return 0; +} + +static int io_tlb_hiwater_set(void *data, u64 val) +{ + struct io_tlb_mem *mem = data; + + /* Only allow setting to zero */ + if (val != 0) + return -EINVAL; + + atomic_long_set(&mem->used_hiwater, val); + return 0; +} + DEFINE_DEBUGFS_ATTRIBUTE(fops_io_tlb_used, io_tlb_used_get, NULL, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_io_tlb_hiwater, io_tlb_hiwater_get, + io_tlb_hiwater_set, "%llu\n"); static void swiotlb_create_debugfs_files(struct io_tlb_mem *mem, const char *dirname) { + atomic_long_set(&mem->total_used, 0); + atomic_long_set(&mem->used_hiwater, 0); + mem->debugfs = debugfs_create_dir(dirname, io_tlb_default_mem.debugfs); if (!mem->nslabs) return; @@ -947,6 +1011,8 @@ static void swiotlb_create_debugfs_files(struct io_tlb_mem *mem, debugfs_create_ulong("io_tlb_nslabs", 0400, mem->debugfs, &mem->nslabs); debugfs_create_file("io_tlb_used", 0400, mem->debugfs, mem, &fops_io_tlb_used); + debugfs_create_file("io_tlb_used_hiwater", 0600, mem->debugfs, mem, + &fops_io_tlb_hiwater); } static int __init __maybe_unused swiotlb_create_default_debugfs(void) |