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    Subject[PATCH v2 3/4] ACPI / sysfs: Add support to allow leading "\" missing in trace_method_name.
    Date
    Since _SB.PCI0 can be used as relative path from root and can be easily
    converted into internal trace_method_name format, we allow users to specify
    trace_method_name using relative paths from root.
    Note this is useful for grub2 for which users failed to pass "\" from the
    grub configuration file.

    Signed-off-by: Lv Zheng <lv.zheng@intel.com>
    ---
    drivers/acpi/sysfs.c | 28 +++++++++++++---------------
    1 file changed, 13 insertions(+), 15 deletions(-)

    diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
    index 8979e4a..40a4265 100644
    --- a/drivers/acpi/sysfs.c
    +++ b/drivers/acpi/sysfs.c
    @@ -164,14 +164,18 @@ static const struct kernel_param_ops param_ops_debug_level = {
    module_param_cb(debug_layer, &param_ops_debug_layer, &acpi_dbg_layer, 0644);
    module_param_cb(debug_level, &param_ops_debug_level, &acpi_dbg_level, 0644);

    -static char* trace_method_name;
    -static bool trace_method_kmalloced;
    +static char trace_method_name[1024];

    int param_set_trace_method_name(const char *val, const struct kernel_param *kp)
    {
    u32 saved_flags = 0;
    + bool is_abs_path = true;

    - if (strlen(val) > 1024) {
    + if (*val != '\\')
    + is_abs_path = false;
    +
    + if ((is_abs_path && strlen(val) > 1023) ||
    + (!is_abs_path && strlen(val) > 1022)) {
    pr_err("%s: string parameter too long\n", kp->name);
    return -ENOSPC;
    }
    @@ -187,19 +191,13 @@ int param_set_trace_method_name(const char *val, const struct kernel_param *kp)
    acpi_gbl_trace_dbg_layer,
    0);

    - if (trace_method_kmalloced)
    - kfree(trace_method_name);
    - trace_method_name = NULL;
    - trace_method_kmalloced = false;
    -
    /* This is a hack. We can't kmalloc in early boot. */
    - if (slab_is_available()) {
    - trace_method_name = kstrdup(val, GFP_KERNEL);
    - if (!trace_method_name)
    - return -ENOMEM;
    - trace_method_kmalloced = true;
    - } else
    - trace_method_name = (char *)val;
    + if (is_abs_path)
    + strcpy(trace_method_name, val);
    + else {
    + trace_method_name[0] = '\\';
    + strcpy(trace_method_name+1, val);
    + }

    /* Restore the original tracer state */
    (void)acpi_debug_trace(trace_method_name,
    --
    1.7.10


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