lib/stackdepot: move documentation comments to stackdepot.h (0621d160) · Commits · git / linux-nf

include/linux/stackdepot.h

+87 −0

Original line number	Diff line number	Diff line
		@@ -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 the 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 pools (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 pools 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 returned from stack_depot_save()
		* @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 __must_check 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

lib/stackdepot.c

+0 −87

Original line number	Diff line number	Diff line
		@@ -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.
		*
		@@ -360,29 +349,6 @@ 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 pools (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 pools 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)
		@@ -477,18 +443,6 @@ 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)
		@@ -497,14 +451,6 @@ 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)
		{
		@@ -537,11 +483,6 @@ 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;
		@@ -553,16 +494,6 @@ 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)
		{
		@@ -575,17 +506,6 @@ 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 returned from stack_depot_save()
		* @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 __must_check stack_depot_set_extra_bits(
		depot_stack_handle_t handle, unsigned int extra_bits)
		{
		@@ -600,13 +520,6 @@ depot_stack_handle_t __must_check stack_depot_set_extra_bits(
		}
		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 };