From 0621d160f1003a8aedd3628133568ecffdd724f7 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Fri, 10 Feb 2023 22:16:06 +0100 Subject: [PATCH] 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 Reviewed-by: Alexander Potapenko Signed-off-by: Andrew Morton --- 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 afdf8ee..e583067 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 the stack depot. + * * Author: Alexander Potapenko * 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 diff --git a/lib/stackdepot.c b/lib/stackdepot.c index aaa5d2f..036da8e 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 * 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 @@ fast_exit: } 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 }; -- 2.7.4