2014-10-16 20:05 GMT+02:00 Jason Cooper <[email protected]>: > On Thu, Oct 16, 2014 at 10:55:57AM -0700, Joe Perches wrote: >> On Thu, 2014-10-16 at 13:48 -0400, Jason Cooper wrote: >> > On Thu, Oct 16, 2014 at 10:25:03AM -0700, Joe Perches wrote: >> > > On Thu, 2014-10-16 at 19:15 +0200, Rickard Strandqvist wrote: >> > > > The buf is used to hold the list of hwrng devices registered. >> > > > The old code ensures we don't walk off the end of buf as we >> > > > fill it, but it's unnecessarily complicated and thus difficult >> > > > to maintain. Simplify it by using strlcat. >> > > > We also ensure the string within buf is NULL terminated >> > > > so the final strlen is ok. >> > > [] >> > > > diff --git a/drivers/char/hw_random/core.c >> > > > b/drivers/char/hw_random/core.c >> > > [] >> > > > @@ -289,16 +288,13 @@ static ssize_t hwrng_attr_available_show(struct >> > > > device *dev, >> > > > return -ERESTARTSYS; >> > > > buf[0] = '\0'; >> > > > list_for_each_entry(rng, &rng_list, list) { >> > > > - strncat(buf, rng->name, PAGE_SIZE - ret - 1); >> > > > - ret += strlen(rng->name); >> > > > - strncat(buf, " ", PAGE_SIZE - ret - 1); >> > > > - ret++; >> > > > + strlcat(buf, rng->name, PAGE_SIZE); >> > > > + strlcat(buf, " ", PAGE_SIZE); >> > > > } >> > > > - strncat(buf, "\n", PAGE_SIZE - ret - 1); >> > > > - ret++; >> > > > + strlcat(buf, "\n", PAGE_SIZE); >> > > > mutex_unlock(&rng_mutex); >> > > > >> > > > - return ret; >> > > > + return strlen(buf); >> > > > } >> > > > >> > > > static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, >> > > >> > > Rickard, can you please use some optimizations here >> > > (and elsewhere) so that strlcat doesn't always have >> > > to strlen the first string and the return doesn't >> > > have to do the strlen too? >> > >> > Joe, is further optimization worth the effort? This function is only >> > called when the end user reads the sysfs file rng_available... >> >> It's unlikely that it matters much here. >> >> I just don't like the repeated and unnecessary strlen. >> >> I do imagine this pattern being repeated though where >> it does matter. > > Agreed. Back to why I like to see descriptions from the author > demonstrating they grok the code they are changing :) >
Hi I will submit a new patch without return strlen. All these features are more or less stupid really. You can also read what Linus thinks about this here. https://plus.google.com/111049168280159033135/posts/1amLbuhWbh5 I keep on trying to get a patch that solves one of these stupid functions, but the strncpy in that case. Kind regards Rickard Strandqvist -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
