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    Subject[PATCH 18/18] lib/stackdepot: move documentation comments to stackdepot.h
    Date
    From: Andrey Konovalov <andreyknvl@google.com>

    Move all interface- and usage-related documentation comments to
    include/linux/stackdepot.h.

    It makes sense to have them in the header where they are available to
    the interface users.

    Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
    ---
    include/linux/stackdepot.h | 87 ++++++++++++++++++++++++++++++++++++++
    lib/stackdepot.c | 87 --------------------------------------
    2 files changed, 87 insertions(+), 87 deletions(-)

    diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h
    index 173740987d8b..a828fbece1ba 100644
    --- a/include/linux/stackdepot.h
    +++ b/include/linux/stackdepot.h
    @@ -2,6 +2,17 @@
    /*
    * Stack depot - a stack trace storage that avoids duplication.
    *
    + * Stack depot is intended to be used by subsystems that need to store and
    + * later retrieve many potentially duplicated stack traces without wasting
    + * memory.
    + *
    + * For example, KASAN needs to save allocation and free stack traces for each
    + * object. Storing two stack traces per object requires a lot of memory (e.g.
    + * SLUB_DEBUG needs 256 bytes per object for that). Since allocation and free
    + * stack traces often repeat, using stack depot allows to save about 100x space.
    + *
    + * Stack traces are never removed from stack depot.
    + *
    * Author: Alexander Potapenko <glider@google.com>
    * Copyright (C) 2016 Google, Inc.
    *
    @@ -57,24 +68,100 @@ static inline void stack_depot_request_early_init(void) { }
    static inline int stack_depot_early_init(void) { return 0; }
    #endif

    +/**
    + * __stack_depot_save - Save a stack trace to stack depot
    + *
    + * @entries: Pointer to the stack trace
    + * @nr_entries: Number of frames in the stack
    + * @alloc_flags: Allocation GFP flags
    + * @can_alloc: Allocate stack slabs (increased chance of failure if false)
    + *
    + * Saves a stack trace from @entries array of size @nr_entries. If @can_alloc is
    + * %true, stack depot can replenish the stack slab pool in case no space is left
    + * (allocates using GFP flags of @alloc_flags). If @can_alloc is %false, avoids
    + * any allocations and fails if no space is left to store the stack trace.
    + *
    + * If the provided stack trace comes from the interrupt context, only the part
    + * up to the interrupt entry is saved.
    + *
    + * Context: Any context, but setting @can_alloc to %false is required if
    + * alloc_pages() cannot be used from the current context. Currently
    + * this is the case for contexts where neither %GFP_ATOMIC nor
    + * %GFP_NOWAIT can be used (NMI, raw_spin_lock).
    + *
    + * Return: Handle of the stack struct stored in depot, 0 on failure
    + */
    depot_stack_handle_t __stack_depot_save(unsigned long *entries,
    unsigned int nr_entries,
    gfp_t gfp_flags, bool can_alloc);

    +/**
    + * stack_depot_save - Save a stack trace to stack depot
    + *
    + * @entries: Pointer to the stack trace
    + * @nr_entries: Number of frames in the stack
    + * @alloc_flags: Allocation GFP flags
    + *
    + * Context: Contexts where allocations via alloc_pages() are allowed.
    + * See __stack_depot_save() for more details.
    + *
    + * Return: Handle of the stack trace stored in depot, 0 on failure
    + */
    depot_stack_handle_t stack_depot_save(unsigned long *entries,
    unsigned int nr_entries, gfp_t gfp_flags);

    +/**
    + * stack_depot_fetch - Fetch a stack trace from stack depot
    + *
    + * @handle: Stack depot handle returned from stack_depot_save()
    + * @entries: Pointer to store the address of the stack trace
    + *
    + * Return: Number of frames for the fetched stack
    + */
    unsigned int stack_depot_fetch(depot_stack_handle_t handle,
    unsigned long **entries);

    +/**
    + * stack_depot_print - Print a stack trace from stack depot
    + *
    + * @stack: Stack depot handle returned from stack_depot_save()
    + */
    void stack_depot_print(depot_stack_handle_t stack);

    +/**
    + * stack_depot_snprint - Print a stack trace from stack depot into a buffer
    + *
    + * @handle: Stack depot handle returned from stack_depot_save()
    + * @buf: Pointer to the print buffer
    + * @size: Size of the print buffer
    + * @spaces: Number of leading spaces to print
    + *
    + * Return: Number of bytes printed
    + */
    int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
    int spaces);

    +/**
    + * stack_depot_set_extra_bits - Set extra bits in a stack depot handle
    + *
    + * @handle: Stack depot handle
    + * @extra_bits: Value to set the extra bits
    + *
    + * Return: Stack depot handle with extra bits set
    + *
    + * Stack depot handles have a few unused bits, which can be used for storing
    + * user-specific information. These bits are transparent to the stack depot.
    + */
    depot_stack_handle_t stack_depot_set_extra_bits(depot_stack_handle_t handle,
    unsigned int extra_bits);

    +/**
    + * stack_depot_get_extra_bits - Retrieve extra bits from a stack depot handle
    + *
    + * @handle: Stack depot handle with extra bits saved
    + *
    + * Return: Extra bits retrieved from the stack depot handle
    + */
    unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle);

    #endif
    diff --git a/lib/stackdepot.c b/lib/stackdepot.c
    index 5128f9486ceb..06bea439d748 100644
    --- a/lib/stackdepot.c
    +++ b/lib/stackdepot.c
    @@ -2,21 +2,10 @@
    /*
    * Stack depot - a stack trace storage that avoids duplication.
    *
    - * Stack depot is intended to be used by subsystems that need to store and
    - * later retrieve many potentially duplicated stack traces without wasting
    - * memory.
    - *
    - * For example, KASAN needs to save allocation and free stack traces for each
    - * object. Storing two stack traces per object requires a lot of memory (e.g.
    - * SLUB_DEBUG needs 256 bytes per object for that). Since allocation and free
    - * stack traces often repeat, using stack depot allows to save about 100x space.
    - *
    * Internally, stack depot maintains a hash table of unique stacktraces. The
    * stack traces themselves are stored contiguously one after another in a set
    * of separate page allocations.
    *
    - * Stack traces are never removed from stack depot.
    - *
    * Author: Alexander Potapenko <glider@google.com>
    * Copyright (C) 2016 Google, Inc.
    *
    @@ -348,29 +337,6 @@ static inline struct stack_record *find_stack(struct stack_record *bucket,
    return NULL;
    }

    -/**
    - * __stack_depot_save - Save a stack trace to stack depot
    - *
    - * @entries: Pointer to the stack trace
    - * @nr_entries: Number of frames in the stack
    - * @alloc_flags: Allocation GFP flags
    - * @can_alloc: Allocate stack slabs (increased chance of failure if false)
    - *
    - * Saves a stack trace from @entries array of size @nr_entries. If @can_alloc is
    - * %true, stack depot can replenish the stack slab pool in case no space is left
    - * (allocates using GFP flags of @alloc_flags). If @can_alloc is %false, avoids
    - * any allocations and fails if no space is left to store the stack trace.
    - *
    - * If the provided stack trace comes from the interrupt context, only the part
    - * up to the interrupt entry is saved.
    - *
    - * Context: Any context, but setting @can_alloc to %false is required if
    - * alloc_pages() cannot be used from the current context. Currently
    - * this is the case for contexts where neither %GFP_ATOMIC nor
    - * %GFP_NOWAIT can be used (NMI, raw_spin_lock).
    - *
    - * Return: Handle of the stack struct stored in depot, 0 on failure
    - */
    depot_stack_handle_t __stack_depot_save(unsigned long *entries,
    unsigned int nr_entries,
    gfp_t alloc_flags, bool can_alloc)
    @@ -466,18 +432,6 @@ depot_stack_handle_t __stack_depot_save(unsigned long *entries,
    }
    EXPORT_SYMBOL_GPL(__stack_depot_save);

    -/**
    - * stack_depot_save - Save a stack trace to stack depot
    - *
    - * @entries: Pointer to the stack trace
    - * @nr_entries: Number of frames in the stack
    - * @alloc_flags: Allocation GFP flags
    - *
    - * Context: Contexts where allocations via alloc_pages() are allowed.
    - * See __stack_depot_save() for more details.
    - *
    - * Return: Handle of the stack trace stored in depot, 0 on failure
    - */
    depot_stack_handle_t stack_depot_save(unsigned long *entries,
    unsigned int nr_entries,
    gfp_t alloc_flags)
    @@ -486,14 +440,6 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries,
    }
    EXPORT_SYMBOL_GPL(stack_depot_save);

    -/**
    - * stack_depot_fetch - Fetch a stack trace from stack depot
    - *
    - * @handle: Stack depot handle returned from stack_depot_save()
    - * @entries: Pointer to store the address of the stack trace
    - *
    - * Return: Number of frames for the fetched stack
    - */
    unsigned int stack_depot_fetch(depot_stack_handle_t handle,
    unsigned long **entries)
    {
    @@ -523,11 +469,6 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle,
    }
    EXPORT_SYMBOL_GPL(stack_depot_fetch);

    -/**
    - * stack_depot_print - Print a stack trace from stack depot
    - *
    - * @stack: Stack depot handle returned from stack_depot_save()
    - */
    void stack_depot_print(depot_stack_handle_t stack)
    {
    unsigned long *entries;
    @@ -539,16 +480,6 @@ void stack_depot_print(depot_stack_handle_t stack)
    }
    EXPORT_SYMBOL_GPL(stack_depot_print);

    -/**
    - * stack_depot_snprint - Print a stack trace from stack depot into a buffer
    - *
    - * @handle: Stack depot handle returned from stack_depot_save()
    - * @buf: Pointer to the print buffer
    - * @size: Size of the print buffer
    - * @spaces: Number of leading spaces to print
    - *
    - * Return: Number of bytes printed
    - */
    int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
    int spaces)
    {
    @@ -561,17 +492,6 @@ int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
    }
    EXPORT_SYMBOL_GPL(stack_depot_snprint);

    -/**
    - * stack_depot_set_extra_bits - Set extra bits in a stack depot handle
    - *
    - * @handle: Stack depot handle
    - * @extra_bits: Value to set the extra bits
    - *
    - * Return: Stack depot handle with extra bits set
    - *
    - * Stack depot handles have a few unused bits, which can be used for storing
    - * user-specific information. These bits are transparent to the stack depot.
    - */
    depot_stack_handle_t stack_depot_set_extra_bits(depot_stack_handle_t handle,
    unsigned int extra_bits)
    {
    @@ -582,13 +502,6 @@ depot_stack_handle_t stack_depot_set_extra_bits(depot_stack_handle_t handle,
    }
    EXPORT_SYMBOL(stack_depot_set_extra_bits);

    -/**
    - * stack_depot_get_extra_bits - Retrieve extra bits from a stack depot handle
    - *
    - * @handle: Stack depot handle with extra bits saved
    - *
    - * Return: Extra bits retrieved from the stack depot handle
    - */
    unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle)
    {
    union handle_parts parts = { .handle = handle };
    --
    2.25.1
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