feature cannot be stopped. If the debug feature is already stopped, it
will stay deactivated.
+Kernel parameters
+-----------------
+The size and log levels of debug logs can be configured early during boot using
+the ``s390dbf`` kernel parameter. The parameter accepts a debug log name, a log
+level, and a log size, separated by colon characters (``:``). To configure only
+a single attribute, either the log level or the log size may be omitted.
+
+To configure multiple debug logs, the parameter may be specified multiple times,
+or multiple parameter sets may be provided in a single instance, separated by
+commas.
+
+Parameter format::
+
+ s390dbf=<name|pattern>:[<level>|-]:[<pages>][,...]
+
+where:
+
+- ``name`` specifies either an exact debug log name or a shell-style wildcard
+ pattern
+- ``level`` specifies the log level, or ``-`` to completely deactivate the log
+- ``pages`` specifies the debug area size in pages
+
+Example::
+
+ s390dbf=cio*:6:128,sclp_err::2
+
+This example sets the log level to 6 and the log size to 128 pages for all debug
+logs whose names start with ``cio``. It also sets the log level of the
+``sclp_err`` debug log to 2.
+
Kernel Interfaces:
------------------
#include <linux/math.h>
#include <linux/minmax.h>
#include <linux/debugfs.h>
+#include <linux/glob.h>
+#include <linux/stringify.h>
#include <asm/debug.h>
static debug_info_t *debug_area_first;
static debug_info_t *debug_area_last;
static DEFINE_MUTEX(debug_mutex);
+extern debug_info_t *__s390dbf_info[], *__s390dbf_info_end[];
static int initialized;
static int debug_critical;
static struct dentry *debug_debugfs_root_entry;
+/* List of debug area parameters to override */
+#define PARAM_UNSET -2
+#define PARAM_NUM 16
+static struct debug_param_t {
+ char name[DEBUG_MAX_NAME_LEN + 1];
+ int level;
+ int pages;
+} debug_param[PARAM_NUM];
+static int debug_param_num;
+
/* functions */
+static void debug_get_param(const char *name, int *level, int *pages)
+{
+ struct debug_param_t *p;
+ int i;
+
+ for (i = 0; i < debug_param_num; i++) {
+ p = &debug_param[i];
+ if (!glob_match(p->name, name))
+ continue;
+ if (level && p->level != PARAM_UNSET) {
+ pr_info("%s: override level to %d\n", name, p->level);
+ *level = p->level;
+ }
+ if (pages && p->pages != PARAM_UNSET) {
+ pr_info("%s: override pages to %d\n", name, p->pages);
+ *pages = p->pages;
+ }
+ }
+}
+
+#define LVL_LEN 10
+#define LVL_FMT "%" __stringify(LVL_LEN) "[^:]"
+#define NAME_FMT "%" __stringify(DEBUG_MAX_NAME_LEN) "[^:]"
+
+static bool __init s390dbf_parse_one(const char *arg, struct debug_param_t *param)
+{
+ struct debug_param_t p = { { 0 }, PARAM_UNSET, PARAM_UNSET };
+ char level[LVL_LEN + 1] = { 0 };
+
+ /* arg: <name|pattern>:[<level>|-]:[<pages>] */
+ if (sscanf(arg, NAME_FMT ":" LVL_FMT ":%d", p.name, level, &p.pages) > 1) {
+ if (strcmp(level, "-") == 0)
+ p.level = DEBUG_OFF_LEVEL;
+ else if (kstrtoint(level, 0, &p.level) != 0)
+ return false;
+ } else if (sscanf(arg, NAME_FMT "::%d", p.name, &p.pages) != 2) {
+ return false;
+ }
+
+ if (p.level != PARAM_UNSET && p.level != DEBUG_OFF_LEVEL &&
+ (p.level < 0 || p.level > DEBUG_MAX_LEVEL))
+ return false;
+ if (p.pages != PARAM_UNSET && p.pages < 0)
+ return false;
+ *param = p;
+
+ return true;
+}
+
+static int __init s390dbf_parse(char *arg)
+{
+ debug_info_t **id;
+ int i, rc = 0;
+
+ while (arg && debug_param_num < PARAM_NUM) {
+ if (s390dbf_parse_one(arg, &debug_param[debug_param_num]))
+ debug_param_num++;
+ else
+ rc = -EINVAL;
+ arg = strchr(arg, ',');
+ if (arg)
+ arg++;
+ }
+
+ /*
+ * Apply level to static debug areas, delay buffer size changes until
+ * regular memory allocations are possible.
+ */
+ for (i = 0, id = __s390dbf_info; &id[i] < __s390dbf_info_end; i++)
+ debug_get_param(id[i]->name, &id[i]->level, NULL);
+
+ return rc;
+}
+early_param("s390dbf", s390dbf_parse);
/*
* debug_areas_alloc
static debug_info_t *debug_info_create(const char *name, int pages_per_area,
int nr_areas, int buf_size, umode_t mode)
{
+ int level = DEBUG_DEFAULT_LEVEL;
debug_info_t *rc;
- rc = debug_info_alloc(name, pages_per_area, nr_areas, buf_size,
- DEBUG_DEFAULT_LEVEL, ALL_AREAS);
+ debug_get_param(name, &level, &pages_per_area);
+ rc = debug_info_alloc(name, pages_per_area, nr_areas, buf_size, level, ALL_AREAS);
if (!rc)
goto out;
return;
}
+ debug_get_param(id->name, &id->level, &pages_per_area);
copy = debug_info_alloc("", pages_per_area, nr_areas, id->buf_size,
id->level, ALL_AREAS);
if (!copy) {
return 0;
}
-/**
- * debug_set_level() - Sets new actual debug level if new_level is valid.
- *
- * @id: handle for debug log
- * @new_level: new debug level
- *
- * Return:
- * none
- */
-void debug_set_level(debug_info_t *id, int new_level)
+static void _debug_set_level(debug_info_t *id, int new_level)
{
unsigned long flags;
id->level = new_level;
raw_spin_unlock_irqrestore(&id->lock, flags);
}
+
+/**
+ * debug_set_level() - Sets new actual debug level if new_level is valid.
+ *
+ * @id: handle for debug log
+ * @new_level: new debug level
+ *
+ * Return:
+ * none
+ */
+void debug_set_level(debug_info_t *id, int new_level)
+{
+ /* Level specified via kernel parameter takes precedence */
+ debug_get_param(id->name, &new_level, NULL);
+
+ _debug_set_level(id, new_level);
+}
EXPORT_SYMBOL(debug_set_level);
/*
goto out;
}
if (str[0] == '-') {
- debug_set_level(id, DEBUG_OFF_LEVEL);
+ _debug_set_level(id, DEBUG_OFF_LEVEL);
rc = user_len;
goto free_str;
} else {
pr_warn("%s is not a valid level for a debug feature\n", str);
rc = -EINVAL;
} else {
- debug_set_level(id, new_level);
+ _debug_set_level(id, new_level);
rc = user_len;
}
free_str:
projects / thirdparty / kernel / linux.git / commitdiff
