Re: [PATCH v2 07/19] lib/stackdepot: rework helpers for depot_alloc_stack

Alexander Potapenko
2023-10-09T09:00:16Z

On Wed, Sep 13, 2023 at 7:15 PM <andrey.konovalov@linux.dev> wrote:
>
> From: Andrey Konovalov <andreyknvl@google.com>
>
> Split code in depot_alloc_stack and depot_init_pool into 3 functions:
>
> 1. depot_keep_next_pool that keeps preallocated memory for the next pool
> if required.
>
> 2. depot_update_pools that moves on to the next pool if there's no space
> left in the current pool, uses preallocated memory for the new current
> pool if required, and calls depot_keep_next_pool otherwise.
>
> 3. depot_alloc_stack that calls depot_update_pools and then allocates
> a stack record as before.
>
> This makes it somewhat easier to follow the logic of depot_alloc_stack
> and also serves as a preparation for implementing the eviction of stack
> records from the stack depot.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>

> +static void depot_keep_next_pool(void **prealloc)
> {
> /*
> - * If the next pool is already initialized or the maximum number of
> + * If the next pool is already saved or the maximum number of
> * pools is reached, do not use the preallocated memory.
> */
> if (!next_pool_required)
It's not mentioned at the top of the file that next_pool_required is
protected by pool_lock, but it is, correct?
Can you please update the comment to reflect that?

> +
> + /*
> + * At this point, either the next pool is kept or the maximum
> + * number of pools is reached. In either case, take note that
> + * keeping another pool is not required.
> + * smp_store_release pairs with smp_load_acquire in stack_depot_save.

As I wrote in the other patch review, I think we'd better keep
parentheses at the end of the function names in the comments (unless
there's a style guide telling us not to).