> There are no checks necessary. Your function worked fine so far for
> the case of zero objects with the pointer returned by kmalloc. If the
> code is correct then it will not dereference the pointer to the zero
> sized array. If not then we may find a bug and fix it.
I suspect you got lucky. The check for a full pidarray[] in the routine
pid_array_load() occurs -after- a pid is put in the array. If a task
showed up in this cpuset at the wrong time, we would fall over and die
in the code:
static int pid_array_load(pid_t *pidarray, int npids, struct cpuset *cs)
{
int n = 0;
struct task_struct *g, *p;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (p->cpuset == cs) {
pidarray[n++] = p->pid; /* Death if pidarray == NULL */
if (unlikely(n == npids))
goto array_full;
}
} while_each_thread(g, p);
Perhaps if you moved the "if (unlikely(n == npids))" test before the
"pidarray[n++] = p->pid" assignment, it would be safe.
And does the next line of code, the call to sort() after the call of
pid_array_load(), work with pidarray == NULL and npids == 0:
npids = pid_array_load(pidarray, npids, cs);
sort(pidarray, npids, sizeof(pid_t), cmppid, NULL); /* <== ?? */
Off hand, I didn't know. I guess it must, or you would have already
tripped over it.
--
I won't rest till it's the best ...
Programmer, Linux Scalability
Paul Jackson <[email protected]> 1.925.600.0401
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