Re: [PATCH v4 14/14] of: Improve __of_add_property_sysfs() readability

On 2025/1/11 04:41, Rob Herring wrote:

quoted

From: Zijun Hu <redacted>

__of_add_property_sysfs() hard codes string "security-" length as 9, but
that is not obvious for readers.

Improve its readability by using strlen().

Does the compiler optimize the strlen call away? Maybe, maybe not. If 
not, that's N calls to strlen() where N is the number of properties in 
your DT. That's in the 1000s easily.

Do you really want to go test enough compiler versions we support to 
feel confident this is optimized away. I don't.

i understand your concern about performance.

what about below solution ?

 int __of_add_property_sysfs(struct device_node *np, struct property *pp)
 {
+#define SECURITY_PREFIX "security-"
        int rc;

        /* Important: Don't leak passwords */
-       bool secure = strncmp(pp->name, "security-", 9) == 0;
+       bool secure = strncmp(pp->name, SECURITY_PREFIX,
sizeof(SECURITY_PREFIX) - 1) == 0;

        if (!IS_ENABLED(CONFIG_SYSFS))
                return 0;