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Date: Tue, 14 Apr 2009 12:47:58 +0200
From: Joerg Roedel <joerg.roedel@....com>
To: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
CC: linux-kernel@...r.kernel.org, mingo@...e.hu
Subject: Re: [PATCH 1/2] dma-debug: add dma_debug_resize_entries() to
adjust the number of dma_debug_entries
On Tue, Apr 14, 2009 at 09:43:18AM +0900, FUJITA Tomonori wrote:
> We use a static value for the number of dma_debug_entries. It can be
> overwritten by a kernel command line option.
>
> Some IOMMUs (e.g. GART) can't set an appropriate value by a kernel
> command line option because they can't know such value until they
> finish initializing up their hardware.
>
> This patch adds dma_debug_resize_entries() enables IOMMUs to adjust
> the number of dma_debug_entries anytime.
>
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
Looks good.
Acked-by: Joerg Roedel <joerg.roedel@....com>
> ---
> include/linux/dma-debug.h | 7 +++++
> lib/dma-debug.c | 67 +++++++++++++++++++++++++++++++++++++++++----
> 2 files changed, 68 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/dma-debug.h b/include/linux/dma-debug.h
> index 28d53cb..171ad8a 100644
> --- a/include/linux/dma-debug.h
> +++ b/include/linux/dma-debug.h
> @@ -32,6 +32,8 @@ extern void dma_debug_add_bus(struct bus_type *bus);
>
> extern void dma_debug_init(u32 num_entries);
>
> +extern int dma_debug_resize_entries(u32 num_entries);
> +
> extern void debug_dma_map_page(struct device *dev, struct page *page,
> size_t offset, size_t size,
> int direction, dma_addr_t dma_addr,
> @@ -91,6 +93,11 @@ static inline void dma_debug_init(u32 num_entries)
> {
> }
>
> +static inline int dma_debug_resize_entries(u32 num_entries)
> +{
> + return 0;
> +}
> +
> static inline void debug_dma_map_page(struct device *dev, struct page *page,
> size_t offset, size_t size,
> int direction, dma_addr_t dma_addr,
> diff --git a/lib/dma-debug.c b/lib/dma-debug.c
> index d3da7ed..01439e6 100644
> --- a/lib/dma-debug.c
> +++ b/lib/dma-debug.c
> @@ -85,6 +85,7 @@ 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 req_entries;
> @@ -257,6 +258,21 @@ static void add_dma_entry(struct dma_debug_entry *entry)
> put_hash_bucket(bucket, &flags);
> }
>
> +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;
> +}
> +
> /* struct dma_entry allocator
> *
> * The next two functions implement the allocator for
> @@ -276,9 +292,7 @@ static struct dma_debug_entry *dma_entry_alloc(void)
> goto out;
> }
>
> - entry = list_entry(free_entries.next, struct dma_debug_entry, list);
> - list_del(&entry->list);
> - memset(entry, 0, sizeof(*entry));
> + entry = __dma_entry_alloc();
>
> #ifdef CONFIG_STACKTRACE
> entry->stacktrace.max_entries = DMA_DEBUG_STACKTRACE_ENTRIES;
> @@ -286,9 +300,6 @@ static struct dma_debug_entry *dma_entry_alloc(void)
> entry->stacktrace.skip = 2;
> save_stack_trace(&entry->stacktrace);
> #endif
> - num_free_entries -= 1;
> - if (num_free_entries < min_free_entries)
> - min_free_entries = num_free_entries;
>
> out:
> spin_unlock_irqrestore(&free_entries_lock, flags);
> @@ -310,6 +321,48 @@ static void dma_entry_free(struct dma_debug_entry *entry)
> spin_unlock_irqrestore(&free_entries_lock, flags);
> }
>
> +int dma_debug_resize_entries(u32 num_entries)
> +{
> + int i, delta, ret = 0;
> + unsigned long flags;
> + struct dma_debug_entry *entry;
> +
> + spin_lock_irqsave(&free_entries_lock, flags);
> +
> + if (nr_total_entries < num_entries) {
> + delta = num_entries - nr_total_entries;
> +
> + for (i = 0; i < delta; i++) {
> + entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
> + if (!entry)
> + break;
> +
> + list_add_tail(&entry->list, &free_entries);
> + }
> +
> + nr_total_entries += i;
> + num_free_entries += i;
> +
> + } else {
> + delta = nr_total_entries - num_entries;
> +
> + for (i = 0; i < delta && !list_empty(&free_entries); i++) {
> + entry = __dma_entry_alloc();
> + kfree(entry);
> + }
> +
> + nr_total_entries -= i;
> + }
> +
> + if (nr_total_entries != num_entries)
> + ret = 1;
> +
> + spin_unlock_irqrestore(&free_entries_lock, flags);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(dma_debug_resize_entries);
> +
> /*
> * DMA-API debugging init code
> *
> @@ -490,6 +543,8 @@ void dma_debug_init(u32 num_entries)
> return;
> }
>
> + nr_total_entries = num_free_entries;
> +
> printk(KERN_INFO "DMA-API: debugging enabled by kernel config\n");
> }
>
> --
> 1.6.0.6
>
>
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