On 12/6/2023 7:53 PM, Jakub Kicinski wrote:

On Tue,  5 Dec 2023 13:12:45 -0800 Tony Nguyen wrote:

quoted

+/**
+ * ice_debugfs_parse_cmd_line - Parse the command line that was passed in
+ * @src: pointer to a buffer holding the command line
+ * @len: size of the buffer in bytes
+ * @argv: pointer to store the command line items
+ * @argc: pointer to store the number of command line items
+ */
+static ssize_t ice_debugfs_parse_cmd_line(const char __user *src, size_t len,
+					  char ***argv, int *argc)
+{
+	char *cmd_buf, *cmd_buf_tmp;
+
+	cmd_buf = memdup_user(src, len);
+	if (IS_ERR(cmd_buf))
+		return PTR_ERR(cmd_buf);
+	cmd_buf[len] = '\0';
+
+	/* the cmd_buf has a newline at the end of the command so
+	 * remove it
+	 */
+	cmd_buf_tmp = strchr(cmd_buf, '\n');
+	if (cmd_buf_tmp) {
+		*cmd_buf_tmp = '\0';
+		len = (size_t)cmd_buf_tmp - (size_t)cmd_buf;
+	}
+
+	*argv = argv_split(GFP_KERNEL, cmd_buf, argc);
+	kfree(cmd_buf);
+	if (!*argv)
+		return -ENOMEM;

I haven't spotted a single caller wanting this full argc/argv parsing.
Can we please not add this complexity until its really needed?

I can remove it, but I use it in all the _write functions. I use the 
argc to make sure I'm only getting one value to a write and I use 
argv[0] to deal with the value.

Honestly I'm not sure how valuable it is to check for a single argument, 
but I'm fairly certain our validation team will file a bug if they pass 
more than one argument and something happens :)

Examples of using argv are on lines 358 and 466 of ice_debugfs.c

I'm open to changing it, just not sure to what

quoted

+/**
+ * ice_debugfs_module_read - read from 'module' file
+ * @filp: the opened file
+ * @buffer: where to write the data for the user to read
+ * @count: the size of the user's buffer
+ * @ppos: file position offset
+ */
+static ssize_t ice_debugfs_module_read(struct file *filp, char __user *buffer,
+				       size_t count, loff_t *ppos)
+{
+	struct dentry *dentry = filp->f_path.dentry;
+	struct ice_pf *pf = filp->private_data;
+	int status, module;
+	char *data = NULL;
+
+	/* don't allow commands if the FW doesn't support it */
+	if (!ice_fwlog_supported(&pf->hw))
+		return -EOPNOTSUPP;
+
+	module = ice_find_module_by_dentry(pf, dentry);
+	if (module < 0) {
+		dev_info(ice_pf_to_dev(pf), "unknown module\n");
+		return -EINVAL;
+	}
+
+	data = vzalloc(ICE_AQ_MAX_BUF_LEN);
+	if (!data) {
+		dev_warn(ice_pf_to_dev(pf), "Unable to allocate memory for FW configuration!\n");
+		return -ENOMEM;

Can we use seq_print() here? It should simplify the reading quite a bit,
not sure how well it works with files that can also be written, tho.

I'm probably missing something here, but how do we get more simple than 
snprintf? I have a function (ice_fwlog_print_module_cfg) that handles 
whether the user has passed a single module ID or they want data on all 
the modules, but it all boils down to snprintf.

I could get rid of ice_fwlog_print_module_cfg() and replace it inline 
with the if/else code if that would be clearer, but I'm not sure 
seq_printf() is helpful because each file is a single quantum of 
information (with the exception of the file that represents all the 
modules). I created a special file to represent all the modules, but 
maybe it's more confusing and I should get rid of it and just make the 
users specify all of the modules in a script.

Would that be easier? Then there is no if/else it's just a single snprintf.

quoted

+/**
+ * ice_debugfs_fwlog_init - setup the debugfs directory
+ * @pf: the ice that is starting up
+ */
+void ice_debugfs_fwlog_init(struct ice_pf *pf)
+{
+	const char *name = pci_name(pf->pdev);
+	struct dentry *fw_modules_dir;
+	struct dentry **fw_modules;
+	int i;
+
+	/* only support fw log commands on PF 0 */
+	if (pf->hw.bus.func)
+		return;
+
+	/* allocate space for this first because if it fails then we don't
+	 * need to unwind
+	 */
+	fw_modules = kcalloc(ICE_NR_FW_LOG_MODULES, sizeof(*fw_modules),
+			     GFP_KERNEL);
+

nit: no new line between call and error check

Will fix

quoted

+	if (!fw_modules) {
+		pr_info("Unable to allocate space for modules\n");

no warnings on allocation failures, there will be a splat for GFP_KERNEL
(checkpatch should catch this)

OK

quoted

+		return;
+	}
+
+	pf->ice_debugfs_pf = debugfs_create_dir(name, ice_debugfs_root);
+	if (IS_ERR(pf->ice_debugfs_pf)) {
+		pr_info("init of debugfs PCI dir failed\n");
+		kfree(fw_modules);
+		return;
+	}
+
+	pf->ice_debugfs_pf_fwlog = debugfs_create_dir("fwlog",
+						      pf->ice_debugfs_pf);
+	if (IS_ERR(pf->ice_debugfs_pf)) {
+		pr_info("init of debugfs fwlog dir failed\n");

If GregKH sees all the info message on debugfs failures he may
complain, DebugFS is supposed to be completely optional.

I'll remove them

Also - free fw_modules ?

This will get fixed by using goto in error paths as you suggested below

You probably want to use goto on all error paths here

quoted

+/**
+ * ice_fwlog_get - Get the firmware logging settings
+ * @hw: pointer to the HW structure
+ * @cfg: config to populate based on current firmware logging settings
+ */
+int ice_fwlog_get(struct ice_hw *hw, struct ice_fwlog_cfg *cfg)
+{
+	if (!ice_fwlog_supported(hw))
+		return -EOPNOTSUPP;
+
+	if (!cfg)
+		return -EINVAL;

can't be, let's avoid defensive programming

OK

quoted

+	return ice_aq_fwlog_get(hw, cfg);

quoted

+void ice_pf_fwlog_update_module(struct ice_pf *pf, int log_level, int module)
+{
+	struct ice_fwlog_module_entry *entries;
+	struct ice_hw *hw = &pf->hw;
+
+	entries = (struct ice_fwlog_module_entry *)hw->fwlog_cfg.module_entries;
+
+	entries[module].log_level = log_level;
+}

Isn't this just

	hw->fwlog_cfg.module_entries[module].log_level = log_level;

? The cast specifically look alarming but unnecessary.

Will change