[PATCH 4/4] printk: Add a device attribute for the per-console loglevel

From: Calvin Owens
Date: Fri Mar 01 2019 - 19:48:37 EST


Signed-off-by: Calvin Owens <calvinowens@xxxxxx>
---
kernel/printk/printk.c | 40 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 67e1e993ab80..e7e602fa2d0b 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2560,8 +2560,48 @@ static int __init keep_bootcon_setup(char *str)

early_param("keep_bootcon", keep_bootcon_setup);

+static ssize_t loglevel_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct console *con = container_of(dev, struct console, dev);
+ return sprintf(buf, "%d\n", con->level);
+}
+
+static ssize_t loglevel_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct console *con = container_of(dev, struct console, dev);
+ ssize_t ret;
+ int tmp;
+
+ ret = kstrtoint(buf, 10, &tmp);
+ if (ret < 0)
+ return ret;
+
+ if (tmp < LOGLEVEL_EMERG)
+ return -ERANGE;
+
+ /*
+ * Mimic the behavior of /dev/kmsg with respect to minimum_loglevel.
+ */
+ if (tmp < minimum_console_loglevel)
+ tmp = minimum_console_loglevel;
+
+ con->level = tmp;
+ return ret;
+}
+
+static DEVICE_ATTR_RW(loglevel);
+
+static struct attribute *console_sysfs_attrs[] = {
+ &dev_attr_loglevel.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(console_sysfs);
+
static struct bus_type console_subsys = {
.name = "console",
+ .dev_groups = console_sysfs_groups,
};

static void console_release(struct device *dev)
--
2.17.1