On 07/28/2014 05:32 AM, Zhang Zhen wrote:
> -static void update_end_of_memory_vars(u64 start, u64 size)
> +static void update_end_of_memory_vars(u64 start, u64 size, bool flag)
> {
> - unsigned long end_pfn = PFN_UP(start + size);
> -
> - if (end_pfn > max_pfn) {
> - max_pfn = end_pfn;
> - max_low_pfn = end_pfn;
> - high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
> + unsigned long end_pfn;
> +
> + if (flag) {
> + end_pfn = PFN_UP(start + size);
> + if (end_pfn > max_pfn) {
> + max_pfn = end_pfn;
> + max_low_pfn = end_pfn;
> + high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
> + }
> + } else {
> + end_pfn = PFN_UP(start);
> + if (end_pfn < max_pfn) {
> + max_pfn = end_pfn;
> + max_low_pfn = end_pfn;
> + high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
> + }
> }
> }
I would really prefer not to see code like this.
This patch takes a small function that did one thing, copies-and-pastes
its code 100%, subtly changes it, and makes it do two things. The only
thing to tell us what the difference between these two subtly different
things is a variable called 'flag'. So the variable is useless in
trying to figure out what each version is supposed to do.
But, this fixes a pretty glaring deficiency in the memory remove code.
I would suggest making two functions. Make it clear that one is to be
used at remove time and the other at add time. Maybe
move_end_of_memory_vars_down()
and
move_end_of_memory_vars_up()
?
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