On 12/21/2015 03:17 PM, Tomas Winkler wrote:
Add entry for dumping current watchdog internal state
Signed-off-by: Tomas Winkler <tomas.winkler@xxxxxxxxx>
---
V2: new in the series
V3: rebase
drivers/watchdog/mei_wdt.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 88 insertions(+)
diff --git a/drivers/watchdog/mei_wdt.c b/drivers/watchdog/mei_wdt.c
index 5b28a1e95ac1..ab9aec218d69 100644
--- a/drivers/watchdog/mei_wdt.c
+++ b/drivers/watchdog/mei_wdt.c
@@ -15,6 +15,7 @@
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
+#include <linux/debugfs.h>
#include <linux/watchdog.h>
#include <linux/uuid.h>
@@ -54,6 +55,24 @@ enum mei_wdt_state {
MEI_WDT_STOPPING,
};
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+static const char *mei_wdt_state_str(enum mei_wdt_state state)
+{
+ switch (state) {
+ case MEI_WDT_IDLE:
+ return "IDLE";
+ case MEI_WDT_START:
+ return "START";
+ case MEI_WDT_RUNNING:
+ return "RUNNING";
+ case MEI_WDT_STOPPING:
+ return "STOPPING";
+ default:
+ return "unknown";
+ }
+}
+#endif /* CONFIG_DEBUG_FS */
+
I still don't understand why this code has to be here instead of
further below (at <----> mark).
struct mei_wdt;
/**
@@ -76,6 +95,8 @@ struct mei_wdt_dev {
* @cldev: mei watchdog client device
* @state: watchdog internal state
* @timeout: watchdog current timeout
+ *
+ * @dbgfs_dir: debugfs dir entry
*/
struct mei_wdt {
struct mei_wdt_dev *mwd;
@@ -83,6 +104,10 @@ struct mei_wdt {
struct mei_cl_device *cldev;
enum mei_wdt_state state;
u16 timeout;
+
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+ struct dentry *dbgfs_dir;
+#endif /* CONFIG_DEBUG_FS */
};
/*
@@ -387,6 +412,65 @@ static int mei_wdt_register(struct mei_wdt *wdt)
return 0;
}
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+
<---->
+static ssize_t mei_dbgfs_read_state(struct file *file, char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ struct mei_wdt *wdt = file->private_data;
+ const size_t bufsz = 32;
+ char buf[32];
+ ssize_t pos = 0;
+
+ pos += scnprintf(buf + pos, bufsz - pos, "state: %s\n",
+ mei_wdt_state_str(wdt->state));
+
Seems to me that "pos = ..." would accomplish exactly the same
without having to pre-initialize pos. I also don't understand the use of
"+ pos" and "- pos" in the parameter field. pos is 0, isn't it ?
When would it ever be non-0 ?
pos = scnprintf(buf, sizeof(buf), "state: %s\n", mei_wdt_state_str(wdt->state));
What am I missing here ?
+ return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
+}
+
+static const struct file_operations dbgfs_fops_state = {
+ .open = simple_open,
+ .read = mei_dbgfs_read_state,
+ .llseek = generic_file_llseek,
+};
+
+static void dbgfs_unregister(struct mei_wdt *wdt)
+{
+ if (!wdt->dbgfs_dir)
+ return;
+ debugfs_remove_recursive(wdt->dbgfs_dir);
debugfs_remove_recursive() checks if the parameter is NULL,
so it is not necessary to check if it is NULL before the call.
+ wdt->dbgfs_dir = NULL;
+}
+
+static int dbgfs_register(struct mei_wdt *wdt)
+{
+ struct dentry *dir, *f;
+
+ dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
+ if (!dir)
+ return -ENOMEM;
+
+ wdt->dbgfs_dir = dir;
+ f = debugfs_create_file("state", S_IRUSR, dir, wdt, &dbgfs_fops_state);
+ if (!f)
+ goto err;
+
+ return 0;
+err:
+ dbgfs_unregister(wdt);
+ return -ENODEV;
The error value is ignored by the caller - why bother returning an error in the first place ?
+}
+
+#else
+
+static inline void dbgfs_unregister(struct mei_wdt *wdt) {}
+
+static inline int dbgfs_register(struct mei_wdt *wdt)
+{
+ return 0;
+}
+#endif /* CONFIG_DEBUG_FS */
+
static int mei_wdt_probe(struct mei_cl_device *cldev,
const struct mei_cl_device_id *id)
{
@@ -414,6 +498,8 @@ static int mei_wdt_probe(struct mei_cl_device *cldev,
if (ret)
goto err_disable;
+ dbgfs_register(wdt);
+
return 0;
err_disable:
@@ -433,6 +519,8 @@ static int mei_wdt_remove(struct mei_cl_device *cldev)
mei_cldev_disable(cldev);
+ dbgfs_unregister(wdt);
+
kfree(wdt);
return 0;
--
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