Messages in this thread |  | | From | Rusty Russell <> | Subject | Re: [PATCH 06/13] cpuset: cleanup cpuset[_can]_attach() | Date | Wed, 02 Jan 2013 15:12:15 +1030 |
| |
Tejun Heo <tj@kernel.org> writes:
> (cc'ing Rusty, hi!) > > Hello, Li. > > On Wed, Dec 26, 2012 at 06:20:11PM +0800, Li Zefan wrote: >> On 2012/11/29 5:34, Tejun Heo wrote: >> > cpuset_can_attach() prepare global variables cpus_attach and >> > cpuset_attach_nodemask_{to|from} which are used by cpuset_attach(). >> > There is no reason to prepare in cpuset_can_attach(). The same >> > information can be accessed from cpuset_attach(). >> > >> > Move the prepartion logic from cpuset_can_attach() to cpuset_attach() >> > and make the global variables static ones inside cpuset_attach(). >> > >> > While at it, convert cpus_attach to cpumask_t from cpumask_var_t. >> > There's no reason to mess with dynamic allocation on a static buffer. >> > >> >> But Rusty had been deprecating the use of cpumask_t. I don't know why >> the final deprecation hasn't been completed yet. > > Hmmm? cpumask_t can't be used for stack but other than that I don't > see how it would be deprecated completely. Rusty, can you please > chime in?
The long-never-quite-complete-plan was for struct cpumask to be undefined when CONFIG_CPUMASK_OFFSTACK=y. That means noone can declare them, or pass them on the stack, since they'll get a compiler error.
Now, there are some cases where it really is a reason to use a static bitmap, and 1/2 a K of wasted space be damned. There's a deliberately-ugly way of doing that: declare a bitmap and use to_cpumask(). Of course, if we ever really want to remove NR_CPUS and make it completely generic, we have to kill all these too, but noone is serious about that.
Cheers, Rusty.
|  |