From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755905AbbLXAZz (ORCPT ); Wed, 23 Dec 2015 19:25:55 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:38502 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751793AbbLXAZx (ORCPT ); Wed, 23 Dec 2015 19:25:53 -0500 Subject: Re: [char-misc-next v3 4/8] watchdog: mei_wdt: add status debugfs entry To: "Winkler, Tomas" , 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> <5678DFF9.6090701@roeck-us.net> <5B8DA87D05A7694D9FA63FD143655C1B540FBDCC@hasmsx108.ger.corp.intel.com> Cc: "Usyskin, Alexander" , "linux-watchdog@vger.kernel.org" , "linux-kernel@vger.kernel.org" From: Guenter Roeck Message-ID: <567B3B90.4000902@roeck-us.net> Date: Wed, 23 Dec 2015 16:25:52 -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: <5B8DA87D05A7694D9FA63FD143655C1B540FBDCC@hasmsx108.ger.corp.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 12/23/2015 02:48 PM, Winkler, Tomas wrote: >> >> 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). > Once it follow closely after enum definition, second in the next patch the > Ifdef is removed since we use the function in debug output and not only in debugfs. > >> >>> 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 ? > Not you are not missing anything, it's just an idiom taken from all my debugfs function with multiline output. I don't think that is a good reason for using the more complex code 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. > Correct, I can be fixed. >> >>> + 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 ? > A function doesn't take responsibility on how it used. For an exported function I would agree, but not in a static function. Thanks, Guenter