On 8/29/23 18:21, Matthew Wilcox wrote:
> On Mon, Aug 28, 2023 at 10:52:12AM +0530, Anshuman Khandual wrote:
>> -static int __init cmdline_parse_stack_guard_gap(char *p)
>> +static int __init cmdline_parse_stack_guard_gap(char *str)
>> {
>> unsigned long val;
>> - char *endptr;
>>
>> - val = simple_strtoul(p, &endptr, 10);
>> - if (!*endptr)
>> - stack_guard_gap = val << PAGE_SHIFT;
>> + if (!str)
>> + return 0;
>
> Please explain how this function can be called with a NULL pointer.
This is an additional check just in case. We have similar constructs
in the following __setup() functions as well.
__setup("hashdist=", set_hashdist)
__setup("numa_balancing=", setup_numabalancing)
__setup("transparent_hugepage=", setup_transparent_hugepage)
Also it might be a better to warn, when returning unhandled with 0
like in those scenarios.
>
>> - return 1;
>> + val = simple_strtoul(str, &str, 10);
>> + if (!*str && val) {
>> + stack_guard_gap = val << PAGE_SHIFT;
>> + return 1;
>> + }
>> + return 0;
>> }
>
> Now you've removed the abillity for someone to say stack_guard_gap=0,
> which seems potentially useful.
In that case, should the following two scenarios be differentiated ?
* stack_guard_gap= - Retains DEFAULT_STACK_GUARD_GAP
* stack_guard_gap=0 - Changes to 0 pages
