On Wed, 14 Feb 2024 at 18:00, Oscar Salvador <osalvador@xxxxxxx> wrote:
>
> In order to move the heavy lifting into page_owner code, this one
> needs to have access to the stack_record structure, which right now
> sits in lib/stackdepot.c.
> Move it to the stackdepot.h header so page_owner can access
> stack_record's struct fields.
>
> Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
> Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
> Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
> ---
> include/linux/stackdepot.h | 47 ++++++++++++++++++++++++++++++++++++++
> lib/stackdepot.c | 45 +-----------------------------------
> 2 files changed, 48 insertions(+), 44 deletions(-)
>
> diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h
> index adcbb8f23600..c4b5ad57c066 100644
> --- a/include/linux/stackdepot.h
> +++ b/include/linux/stackdepot.h
> @@ -30,6 +30,53 @@ typedef u32 depot_stack_handle_t;
> */
> #define STACK_DEPOT_EXTRA_BITS 5
>
> +#define DEPOT_HANDLE_BITS (sizeof(depot_stack_handle_t) * 8)
> +
> +#define DEPOT_POOL_ORDER 2 /* Pool size order, 4 pages */
> +#define DEPOT_POOL_SIZE (1LL << (PAGE_SHIFT + DEPOT_POOL_ORDER))
> +#define DEPOT_STACK_ALIGN 4
> +#define DEPOT_OFFSET_BITS (DEPOT_POOL_ORDER + PAGE_SHIFT - DEPOT_STACK_ALIGN)
> +#define DEPOT_POOL_INDEX_BITS (DEPOT_HANDLE_BITS - DEPOT_OFFSET_BITS - \
> + STACK_DEPOT_EXTRA_BITS)
> +
> +#ifdef CONFIG_STACKDEPOT
> +/* Compact structure that stores a reference to a stack. */
> +union handle_parts {
> + depot_stack_handle_t handle;
> + struct {
> + /* pool_index is offset by 1 */
> + u32 pool_index : DEPOT_POOL_INDEX_BITS;
> + u32 offset : DEPOT_OFFSET_BITS;
> + u32 extra : STACK_DEPOT_EXTRA_BITS;
> + };
> +};
> +
> +struct stack_record {
> + struct list_head hash_list; /* Links in the hash table */
> + u32 hash; /* Hash in hash table */
> + u32 size; /* Number of stored frames */
> + union handle_parts handle; /* Constant after initialization */
> + refcount_t count;
> + union {
> + unsigned long entries[CONFIG_STACKDEPOT_MAX_FRAMES]; /* Frames */
> + struct {
> + /*
> + * An important invariant of the implementation is to
> + * only place a stack record onto the freelist iff its
> + * refcount is zero. Because stack records with a zero
> + * refcount are never considered as valid, it is safe to
> + * union @entries and freelist management state below.
> + * Conversely, as soon as an entry is off the freelist
> + * and its refcount becomes non-zero, the below must not
> + * be accessed until being placed back on the freelist.
> + */
> + struct list_head free_list; /* Links in the freelist */
> + unsigned long rcu_state; /* RCU cookie */
> + };
> + };
> +};
> +#endif
> +
> typedef u32 depot_flags_t;
>
> /*
> diff --git a/lib/stackdepot.c b/lib/stackdepot.c
> index c043a4186bc5..4a661a6777da 100644
> --- a/lib/stackdepot.c
> +++ b/lib/stackdepot.c
> @@ -36,55 +36,12 @@
> #include <linux/memblock.h>
> #include <linux/kasan-enabled.h>
>
> -#define DEPOT_HANDLE_BITS (sizeof(depot_stack_handle_t) * 8)
> -
> -#define DEPOT_POOL_ORDER 2 /* Pool size order, 4 pages */
> -#define DEPOT_POOL_SIZE (1LL << (PAGE_SHIFT + DEPOT_POOL_ORDER))
> -#define DEPOT_STACK_ALIGN 4
> -#define DEPOT_OFFSET_BITS (DEPOT_POOL_ORDER + PAGE_SHIFT - DEPOT_STACK_ALIGN)
> -#define DEPOT_POOL_INDEX_BITS (DEPOT_HANDLE_BITS - DEPOT_OFFSET_BITS - \
> - STACK_DEPOT_EXTRA_BITS)
> #define DEPOT_POOLS_CAP 8192
> -/* The pool_index is offset by 1 so the first record does not have a 0 handle. */
> +/* The pool_index is offset by 1 so the first record does not have a 0 handle */
Why this comment change? We lost the '.' -- for future reference, it'd
be good to ensure unnecessary changes don't creep into the diff. This
is just nitpicking, and I've already reviewed this change, so no need
to send a v+1.
