Messages in this thread Patch in this message | | | Subject | Re: [char-misc-next v3 4/8] watchdog: mei_wdt: add status debugfs entry | From | Guenter Roeck <> | Date | Mon, 21 Dec 2015 21:30:33 -0800 |
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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@intel.com> > --- > 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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