lib/stackdepot: move documentation comments to stackdepot.h
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. [akpm@linux-foundation.org: grammar fix, per Alexander] Link: https://lkml.kernel.org/r/fbfee41495b306dd8881f9b1c1b80999c885e82f.1676063693.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Alexander Potapenko <glider@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Andrey Konovalov
Andrew Morton
parent
b232b9995a
commit
0621d160f1
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@ -2,6 +2,17 @@
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/*
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* Stack depot - a stack trace storage that avoids duplication.
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*
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* Stack depot is intended to be used by subsystems that need to store and
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* later retrieve many potentially duplicated stack traces without wasting
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* memory.
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*
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* For example, KASAN needs to save allocation and free stack traces for each
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* object. Storing two stack traces per object requires a lot of memory (e.g.
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* SLUB_DEBUG needs 256 bytes per object for that). Since allocation and free
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* stack traces often repeat, using stack depot allows to save about 100x space.
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*
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* Stack traces are never removed from the stack depot.
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*
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* Author: Alexander Potapenko <glider@google.com>
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* Copyright (C) 2016 Google, Inc.
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*
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@ -57,24 +68,100 @@ static inline void stack_depot_request_early_init(void) { }
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static inline int stack_depot_early_init(void) { return 0; }
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#endif
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/**
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* __stack_depot_save - Save a stack trace to stack depot
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*
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* @entries: Pointer to the stack trace
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* @nr_entries: Number of frames in the stack
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* @alloc_flags: Allocation GFP flags
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* @can_alloc: Allocate stack pools (increased chance of failure if false)
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*
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* Saves a stack trace from @entries array of size @nr_entries. If @can_alloc is
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* %true, stack depot can replenish the stack pools in case no space is left
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* (allocates using GFP flags of @alloc_flags). If @can_alloc is %false, avoids
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* any allocations and fails if no space is left to store the stack trace.
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*
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* If the provided stack trace comes from the interrupt context, only the part
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* up to the interrupt entry is saved.
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*
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* Context: Any context, but setting @can_alloc to %false is required if
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* alloc_pages() cannot be used from the current context. Currently
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* this is the case for contexts where neither %GFP_ATOMIC nor
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* %GFP_NOWAIT can be used (NMI, raw_spin_lock).
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*
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* Return: Handle of the stack struct stored in depot, 0 on failure
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*/
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depot_stack_handle_t __stack_depot_save(unsigned long *entries,
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unsigned int nr_entries,
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gfp_t gfp_flags, bool can_alloc);
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/**
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* stack_depot_save - Save a stack trace to stack depot
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*
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* @entries: Pointer to the stack trace
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* @nr_entries: Number of frames in the stack
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* @alloc_flags: Allocation GFP flags
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*
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* Context: Contexts where allocations via alloc_pages() are allowed.
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* See __stack_depot_save() for more details.
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*
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* Return: Handle of the stack trace stored in depot, 0 on failure
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*/
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depot_stack_handle_t stack_depot_save(unsigned long *entries,
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unsigned int nr_entries, gfp_t gfp_flags);
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/**
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* stack_depot_fetch - Fetch a stack trace from stack depot
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*
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* @handle: Stack depot handle returned from stack_depot_save()
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* @entries: Pointer to store the address of the stack trace
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*
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* Return: Number of frames for the fetched stack
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*/
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unsigned int stack_depot_fetch(depot_stack_handle_t handle,
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unsigned long **entries);
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/**
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* stack_depot_print - Print a stack trace from stack depot
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*
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* @stack: Stack depot handle returned from stack_depot_save()
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*/
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void stack_depot_print(depot_stack_handle_t stack);
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/**
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* stack_depot_snprint - Print a stack trace from stack depot into a buffer
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*
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* @handle: Stack depot handle returned from stack_depot_save()
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* @buf: Pointer to the print buffer
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* @size: Size of the print buffer
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* @spaces: Number of leading spaces to print
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*
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* Return: Number of bytes printed
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*/
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int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
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int spaces);
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/**
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* stack_depot_set_extra_bits - Set extra bits in a stack depot handle
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*
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* @handle: Stack depot handle returned from stack_depot_save()
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* @extra_bits: Value to set the extra bits
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*
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* Return: Stack depot handle with extra bits set
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*
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* Stack depot handles have a few unused bits, which can be used for storing
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* user-specific information. These bits are transparent to the stack depot.
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*/
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depot_stack_handle_t __must_check stack_depot_set_extra_bits(
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depot_stack_handle_t handle, unsigned int extra_bits);
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/**
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* stack_depot_get_extra_bits - Retrieve extra bits from a stack depot handle
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*
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* @handle: Stack depot handle with extra bits saved
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*
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* Return: Extra bits retrieved from the stack depot handle
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*/
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unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle);
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#endif
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@ -2,21 +2,10 @@
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/*
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* Stack depot - a stack trace storage that avoids duplication.
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*
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* Stack depot is intended to be used by subsystems that need to store and
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* later retrieve many potentially duplicated stack traces without wasting
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* memory.
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*
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* For example, KASAN needs to save allocation and free stack traces for each
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* object. Storing two stack traces per object requires a lot of memory (e.g.
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* SLUB_DEBUG needs 256 bytes per object for that). Since allocation and free
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* stack traces often repeat, using stack depot allows to save about 100x space.
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*
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* Internally, stack depot maintains a hash table of unique stacktraces. The
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* stack traces themselves are stored contiguously one after another in a set
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* of separate page allocations.
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*
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* Stack traces are never removed from stack depot.
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*
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* Author: Alexander Potapenko <glider@google.com>
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* Copyright (C) 2016 Google, Inc.
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*
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@ -360,29 +349,6 @@ static inline struct stack_record *find_stack(struct stack_record *bucket,
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return NULL;
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}
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/**
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* __stack_depot_save - Save a stack trace to stack depot
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*
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* @entries: Pointer to the stack trace
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* @nr_entries: Number of frames in the stack
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* @alloc_flags: Allocation GFP flags
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* @can_alloc: Allocate stack pools (increased chance of failure if false)
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*
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* Saves a stack trace from @entries array of size @nr_entries. If @can_alloc is
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* %true, stack depot can replenish the stack pools in case no space is left
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* (allocates using GFP flags of @alloc_flags). If @can_alloc is %false, avoids
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* any allocations and fails if no space is left to store the stack trace.
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*
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* If the provided stack trace comes from the interrupt context, only the part
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* up to the interrupt entry is saved.
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*
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* Context: Any context, but setting @can_alloc to %false is required if
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* alloc_pages() cannot be used from the current context. Currently
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* this is the case for contexts where neither %GFP_ATOMIC nor
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* %GFP_NOWAIT can be used (NMI, raw_spin_lock).
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*
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* Return: Handle of the stack struct stored in depot, 0 on failure
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*/
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depot_stack_handle_t __stack_depot_save(unsigned long *entries,
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unsigned int nr_entries,
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gfp_t alloc_flags, bool can_alloc)
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@ -477,18 +443,6 @@ fast_exit:
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}
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EXPORT_SYMBOL_GPL(__stack_depot_save);
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/**
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* stack_depot_save - Save a stack trace to stack depot
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*
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* @entries: Pointer to the stack trace
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* @nr_entries: Number of frames in the stack
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* @alloc_flags: Allocation GFP flags
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*
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* Context: Contexts where allocations via alloc_pages() are allowed.
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* See __stack_depot_save() for more details.
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*
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* Return: Handle of the stack trace stored in depot, 0 on failure
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*/
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depot_stack_handle_t stack_depot_save(unsigned long *entries,
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unsigned int nr_entries,
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gfp_t alloc_flags)
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@ -497,14 +451,6 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries,
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}
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EXPORT_SYMBOL_GPL(stack_depot_save);
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/**
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* stack_depot_fetch - Fetch a stack trace from stack depot
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*
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* @handle: Stack depot handle returned from stack_depot_save()
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* @entries: Pointer to store the address of the stack trace
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*
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* Return: Number of frames for the fetched stack
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*/
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unsigned int stack_depot_fetch(depot_stack_handle_t handle,
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unsigned long **entries)
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{
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@ -537,11 +483,6 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle,
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}
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EXPORT_SYMBOL_GPL(stack_depot_fetch);
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/**
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* stack_depot_print - Print a stack trace from stack depot
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*
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* @stack: Stack depot handle returned from stack_depot_save()
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*/
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void stack_depot_print(depot_stack_handle_t stack)
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{
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unsigned long *entries;
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@ -553,16 +494,6 @@ void stack_depot_print(depot_stack_handle_t stack)
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}
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EXPORT_SYMBOL_GPL(stack_depot_print);
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/**
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* stack_depot_snprint - Print a stack trace from stack depot into a buffer
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*
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* @handle: Stack depot handle returned from stack_depot_save()
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* @buf: Pointer to the print buffer
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* @size: Size of the print buffer
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* @spaces: Number of leading spaces to print
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*
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* Return: Number of bytes printed
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*/
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int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
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int spaces)
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{
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@ -575,17 +506,6 @@ int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
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}
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EXPORT_SYMBOL_GPL(stack_depot_snprint);
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/**
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* stack_depot_set_extra_bits - Set extra bits in a stack depot handle
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*
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* @handle: Stack depot handle returned from stack_depot_save()
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* @extra_bits: Value to set the extra bits
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*
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* Return: Stack depot handle with extra bits set
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*
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* Stack depot handles have a few unused bits, which can be used for storing
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* user-specific information. These bits are transparent to the stack depot.
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*/
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depot_stack_handle_t __must_check stack_depot_set_extra_bits(
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depot_stack_handle_t handle, unsigned int extra_bits)
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{
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@ -600,13 +520,6 @@ depot_stack_handle_t __must_check stack_depot_set_extra_bits(
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}
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EXPORT_SYMBOL(stack_depot_set_extra_bits);
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/**
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* stack_depot_get_extra_bits - Retrieve extra bits from a stack depot handle
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*
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* @handle: Stack depot handle with extra bits saved
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*
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* Return: Extra bits retrieved from the stack depot handle
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*/
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unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle)
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{
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union handle_parts parts = { .handle = handle };
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