Re: Ipmi modules and linux-4.19.1

[Corey Minyard <cminyard@mvista.com>]

On 12/20/18 10:22 AM, Paul E. McKenney wrote:
> On Thu, Dec 20, 2018 at 08:05:14AM -0800, Tejun Heo wrote:
>> Hello,
>>
>> On Thu, Dec 20, 2018 at 08:04:08AM -0800, Paul E. McKenney wrote:
>>>> Yes, it is possible.  Just do something like this:
>>>>
>>>> 	struct srcu_struct my_srcu_struct;
>>>>
>>>> And before the first use of my_srcu_struct, do this:
>>>>
>>>> 	init_srcu_struct(&my_srcu_struct);
>>>>
>>>> This will result in alloc_percpu() being invoked to allocate the
>>>> needed per-CPU space.
>>>>
>>>> If my_srcu_struct is used in a module or some such, then to avoid memory
>>>> leaks, after the last use of my_srcu_struct, do this:
>>>>
>>>> 	cleanup_srcu_struct(&my_srcu_struct);
>>>>
>>>> There are several places in the kernel that take this approach.
>> Oops, my bad.  Somehow I thought the dynamic init didn't exist (I
>> checked the header but somehow completely skipped over them).  Thanks
>> for the explanation!
> No problem, especially given that if things go as they usually do, I
> will provide you ample opportunity to return the favor.  ;-)

Ok, I didn't realize that SRCU took up so much space.  It's true that 
this isn't
something that requires performance, but SRCU was awfully convenient to
use for this.

Unfortunately, it's not just a matter of adding the init_srcu_struct() 
to the
__init function.  I'm going to have to hunt down all the initial startup 
points
and add it there, and rework some of the other initialization code..  
But that's
something I can do.

Unless someone else would rather do it :-).

-corey