lkml.org 
[lkml]   [2012]   [Sep]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Subject[PATCH] dma-debug: Add dma map/unmap error tracking support
    From
    Date
    A recent dma mapping error analysis effort showed that a large precentage
    of dma_map_single() and dma_map_page() returns are not checked for mapping
    errors. Reference: https://lkml.org/lkml/2012/8/10/326

    Adding support for tracking dma mapping and unmapping errors to help assess
    the following:

    When do dma mapping errors get detected?
    How often do these errors occur?
    Why don't we see failures related to missing dma mapping error checks?
    Are they silent failures?

    Signed-off-by: Shuah Khan <shuah.khan@hp.com>
    ---
    Documentation/DMA-API.txt | 7 +++++++
    lib/dma-debug.c | 26 +++++++++++++++++++++++++-
    2 files changed, 32 insertions(+), 1 deletion(-)

    diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
    index 66bd97a..ee10a11 100644
    --- a/Documentation/DMA-API.txt
    +++ b/Documentation/DMA-API.txt
    @@ -638,6 +638,13 @@ this directory the following files can currently be found:
    dma-api/error_count This file is read-only and shows the total
    numbers of errors found.

    + dma-api/dma_map_errors This file is read-only and shows the total
    + number of dma mapping errors detected.
    +
    + dma-api/dma_unmap_errors
    + This file is read-only and shows the total
    + number of invalid dma unmapping attempts.
    +
    dma-api/num_errors The number in this file shows how many
    warnings will be printed to the kernel log
    before it stops. This number is initialized to
    diff --git a/lib/dma-debug.c b/lib/dma-debug.c
    index 66ce414..8596114 100644
    --- a/lib/dma-debug.c
    +++ b/lib/dma-debug.c
    @@ -83,6 +83,10 @@ static u32 global_disable __read_mostly;
    /* Global error count */
    static u32 error_count;

    +/* dma mapping error counts */
    +static u32 dma_map_errors;
    +static u32 dma_unmap_errors;
    +
    /* Global error show enable*/
    static u32 show_all_errors __read_mostly;
    /* Number of errors to show */
    @@ -104,6 +108,8 @@ static struct dentry *show_num_errors_dent __read_mostly;
    static struct dentry *num_free_entries_dent __read_mostly;
    static struct dentry *min_free_entries_dent __read_mostly;
    static struct dentry *filter_dent __read_mostly;
    +static struct dentry *dma_map_errors_dent __read_mostly;
    +static struct dentry *dma_unmap_errors_dent __read_mostly;

    /* per-driver filter related state */

    @@ -695,6 +701,19 @@ static int dma_debug_fs_init(void)
    if (!filter_dent)
    goto out_err;

    + dma_map_errors_dent = debugfs_create_u32("dma_map_errors", 0444,
    + dma_debug_dent,
    + &dma_map_errors);
    +
    + if (!dma_map_errors_dent)
    + goto out_err;
    +
    + dma_unmap_errors_dent = debugfs_create_u32("dma_unmap_errors", 0444,
    + dma_debug_dent,
    + &dma_unmap_errors);
    + if (!dma_unmap_errors_dent)
    + goto out_err;
    +
    return 0;

    out_err:
    @@ -850,6 +869,7 @@ static void check_unmap(struct dma_debug_entry *ref)
    unsigned long flags;

    if (dma_mapping_error(ref->dev, ref->dev_addr)) {
    + dma_unmap_errors += 1;
    err_printk(ref->dev, NULL, "DMA-API: device driver tries "
    "to free an invalid DMA memory address\n");
    return;
    @@ -1022,8 +1042,12 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
    if (unlikely(global_disable))
    return;

    - if (unlikely(dma_mapping_error(dev, dma_addr)))
    + if (unlikely(dma_mapping_error(dev, dma_addr))) {
    + dma_map_errors += 1;
    + err_printk(dev, NULL,
    + "DMA-API: dma_map_page() returned error\n");
    return;
    + }

    entry = dma_entry_alloc();
    if (!entry)
    --
    1.7.9.5




    \
     
     \ /
      Last update: 2012-09-02 17:01    [W:0.029 / U:0.972 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site