From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753601AbbLVFai (ORCPT ); Tue, 22 Dec 2015 00:30:38 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:46589 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751623AbbLVFag (ORCPT ); Tue, 22 Dec 2015 00:30:36 -0500 Subject: Re: [char-misc-next v3 4/8] watchdog: mei_wdt: add status debugfs entry To: Tomas Winkler , Greg Kroah-Hartman , Wim Van Sebroeck References: <1450739881-3923-1-git-send-email-tomas.winkler@intel.com> <1450739881-3923-5-git-send-email-tomas.winkler@intel.com> Cc: Alexander Usyskin , linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org From: Guenter Roeck Message-ID: <5678DFF9.6090701@roeck-us.net> Date: Mon, 21 Dec 2015 21:30:33 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: <1450739881-3923-5-git-send-email-tomas.winkler@intel.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: linux@roeck-us.net X-Authenticated-Sender: bh-25.webhostbox.net: linux@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/21/2015 03:17 PM, Tomas Winkler wrote: > Add entry for dumping current watchdog internal state > > Signed-off-by: Tomas Winkler > --- > 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 > #include > #include > +#include > #include > > #include > @@ -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; >