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Subject[PATCH 4/4] 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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