Skip to content

Commit

Permalink
lib/stackdepot: put functions in logical order
Browse files Browse the repository at this point in the history 
Patch series "lib/stackdepot: fixes and clean-ups", v2.

A set of fixes, comments, and clean-ups I came up with while reading
the stack depot code.


This patch (of 18):

Put stack depot functions' declarations and definitions in a more logical
order:

1. Functions that save stack traces into stack depot.
2. Functions that fetch and print stack traces.
3. stack_depot_get_extra_bits that operates on stack depot handles
   and does not interact with the stack depot storage.

No functional changes.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/daca1319b665d826b94c596b992a8d8117846147.1676063693.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <[email protected]>
Reviewed-by: Alexander Potapenko <[email protected]>
Cc: Evgenii Stepanov <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
  • Loading branch information
@xairy @akpm00
xairy authored and akpm00 committed Feb 17, 2023
1 parent 6bdfc60 commit 15ef6a9
Show file tree
Hide file tree
Showing 2 changed files with 165 additions and 164 deletions.
15 changes: 8 additions & 7 deletions include/linux/stackdepot.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -14,17 +14,13 @@
#include <linux/gfp.h>

typedef u32 depot_stack_handle_t;

/*
* Number of bits in the handle that stack depot doesn't use. Users may store
* information in them.
*/
#define STACK_DEPOT_EXTRA_BITS 5

depot_stack_handle_t __stack_depot_save(unsigned long *entries,
unsigned int nr_entries,
unsigned int extra_bits,
gfp_t gfp_flags, bool can_alloc);

/*
* Every user of stack depot has to call stack_depot_init() during its own init
* when it's decided that it will be calling stack_depot_save() later. This is
Expand Down Expand Up @@ -59,17 +55,22 @@ static inline void stack_depot_want_early_init(void) { }
static inline int stack_depot_early_init(void) { return 0; }
#endif

depot_stack_handle_t __stack_depot_save(unsigned long *entries,
unsigned int nr_entries,
unsigned int extra_bits,
gfp_t gfp_flags, bool can_alloc);

depot_stack_handle_t stack_depot_save(unsigned long *entries,
unsigned int nr_entries, gfp_t gfp_flags);

unsigned int stack_depot_fetch(depot_stack_handle_t handle,
unsigned long **entries);

unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle);
void stack_depot_print(depot_stack_handle_t stack);

int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
int spaces);

void stack_depot_print(depot_stack_handle_t stack);
unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle);

#endif
314 changes: 157 additions & 157 deletions lib/stackdepot.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -79,84 +79,6 @@ static int next_slab_inited;
static size_t depot_offset;
static DEFINE_RAW_SPINLOCK(depot_lock);

unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle)
{
union handle_parts parts = { .handle = handle };

return parts.extra;
}
EXPORT_SYMBOL(stack_depot_get_extra_bits);

static bool init_stack_slab(void **prealloc)
{
if (!*prealloc)
return false;
/*
* This smp_load_acquire() pairs with smp_store_release() to
* |next_slab_inited| below and in depot_alloc_stack().
*/
if (smp_load_acquire(&next_slab_inited))
return true;
if (stack_slabs[depot_index] == NULL) {
stack_slabs[depot_index] = *prealloc;
*prealloc = NULL;
} else {
/* If this is the last depot slab, do not touch the next one. */
if (depot_index + 1 < STACK_ALLOC_MAX_SLABS) {
stack_slabs[depot_index + 1] = *prealloc;
*prealloc = NULL;
}
/*
* This smp_store_release pairs with smp_load_acquire() from
* |next_slab_inited| above and in stack_depot_save().
*/
smp_store_release(&next_slab_inited, 1);
}
return true;
}

/* Allocation of a new stack in raw storage */
static struct stack_record *
depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc)
{
struct stack_record *stack;
size_t required_size = struct_size(stack, entries, size);

required_size = ALIGN(required_size, 1 << STACK_ALLOC_ALIGN);

if (unlikely(depot_offset + required_size > STACK_ALLOC_SIZE)) {
if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) {
WARN_ONCE(1, "Stack depot reached limit capacity");
return NULL;
}
depot_index++;
depot_offset = 0;
/*
* smp_store_release() here pairs with smp_load_acquire() from
* |next_slab_inited| in stack_depot_save() and
* init_stack_slab().
*/
if (depot_index + 1 < STACK_ALLOC_MAX_SLABS)
smp_store_release(&next_slab_inited, 0);
}
init_stack_slab(prealloc);
if (stack_slabs[depot_index] == NULL)
return NULL;

stack = stack_slabs[depot_index] + depot_offset;

stack->hash = hash;
stack->size = size;
stack->handle.slabindex = depot_index;
stack->handle.offset = depot_offset >> STACK_ALLOC_ALIGN;
stack->handle.valid = 1;
stack->handle.extra = 0;
memcpy(stack->entries, entries, flex_array_size(stack, entries, size));
depot_offset += required_size;

return stack;
}

/* one hash table bucket entry per 16kB of memory */
#define STACK_HASH_SCALE 14
/* limited between 4k and 1M buckets */
Expand Down Expand Up @@ -270,6 +192,76 @@ int stack_depot_init(void)
}
EXPORT_SYMBOL_GPL(stack_depot_init);

static bool init_stack_slab(void **prealloc)
{
if (!*prealloc)
return false;
/*
* This smp_load_acquire() pairs with smp_store_release() to
* |next_slab_inited| below and in depot_alloc_stack().
*/
if (smp_load_acquire(&next_slab_inited))
return true;
if (stack_slabs[depot_index] == NULL) {
stack_slabs[depot_index] = *prealloc;
*prealloc = NULL;
} else {
/* If this is the last depot slab, do not touch the next one. */
if (depot_index + 1 < STACK_ALLOC_MAX_SLABS) {
stack_slabs[depot_index + 1] = *prealloc;
*prealloc = NULL;
}
/*
* This smp_store_release pairs with smp_load_acquire() from
* |next_slab_inited| above and in stack_depot_save().
*/
smp_store_release(&next_slab_inited, 1);
}
return true;
}

/* Allocation of a new stack in raw storage */
static struct stack_record *
depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc)
{
struct stack_record *stack;
size_t required_size = struct_size(stack, entries, size);

required_size = ALIGN(required_size, 1 << STACK_ALLOC_ALIGN);

if (unlikely(depot_offset + required_size > STACK_ALLOC_SIZE)) {
if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) {
WARN_ONCE(1, "Stack depot reached limit capacity");
return NULL;
}
depot_index++;
depot_offset = 0;
/*
* smp_store_release() here pairs with smp_load_acquire() from
* |next_slab_inited| in stack_depot_save() and
* init_stack_slab().
*/
if (depot_index + 1 < STACK_ALLOC_MAX_SLABS)
smp_store_release(&next_slab_inited, 0);
}
init_stack_slab(prealloc);
if (stack_slabs[depot_index] == NULL)
return NULL;

stack = stack_slabs[depot_index] + depot_offset;

stack->hash = hash;
stack->size = size;
stack->handle.slabindex = depot_index;
stack->handle.offset = depot_offset >> STACK_ALLOC_ALIGN;
stack->handle.valid = 1;
stack->handle.extra = 0;
memcpy(stack->entries, entries, flex_array_size(stack, entries, size));
depot_offset += required_size;

return stack;
}

/* Calculate hash for a stack */
static inline u32 hash_stack(unsigned long *entries, unsigned int size)
{
Expand Down Expand Up @@ -309,85 +301,6 @@ static inline struct stack_record *find_stack(struct stack_record *bucket,
return NULL;
}

/**
* stack_depot_snprint - print stack entries from a depot into a buffer
*
* @handle: Stack depot handle which was 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)
{
unsigned long *entries;
unsigned int nr_entries;

nr_entries = stack_depot_fetch(handle, &entries);
return nr_entries ? stack_trace_snprint(buf, size, entries, nr_entries,
spaces) : 0;
}
EXPORT_SYMBOL_GPL(stack_depot_snprint);

/**
* stack_depot_print - print stack entries from a depot
*
* @stack: Stack depot handle which was returned from
* stack_depot_save().
*
*/
void stack_depot_print(depot_stack_handle_t stack)
{
unsigned long *entries;
unsigned int nr_entries;

nr_entries = stack_depot_fetch(stack, &entries);
if (nr_entries > 0)
stack_trace_print(entries, nr_entries, 0);
}
EXPORT_SYMBOL_GPL(stack_depot_print);

/**
* stack_depot_fetch - Fetch stack entries from a depot
*
* @handle: Stack depot handle which was returned from
* stack_depot_save().
* @entries: Pointer to store the entries address
*
* Return: The number of trace entries for this depot.
*/
unsigned int stack_depot_fetch(depot_stack_handle_t handle,
unsigned long **entries)
{
union handle_parts parts = { .handle = handle };
void *slab;
size_t offset = parts.offset << STACK_ALLOC_ALIGN;
struct stack_record *stack;

*entries = NULL;
if (!handle)
return 0;

if (parts.slabindex > depot_index) {
WARN(1, "slab index %d out of bounds (%d) for stack id %08x\n",
parts.slabindex, depot_index, handle);
return 0;
}
slab = stack_slabs[parts.slabindex];
if (!slab)
return 0;
stack = slab + offset;

*entries = stack->entries;
return stack->size;
}
EXPORT_SYMBOL_GPL(stack_depot_fetch);

/**
* __stack_depot_save - Save a stack trace from an array
*
Expand Down Expand Up @@ -533,3 +446,90 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries,
return __stack_depot_save(entries, nr_entries, 0, alloc_flags, true);
}
EXPORT_SYMBOL_GPL(stack_depot_save);

/**
* stack_depot_fetch - Fetch stack entries from a depot
*
* @handle: Stack depot handle which was returned from
* stack_depot_save().
* @entries: Pointer to store the entries address
*
* Return: The number of trace entries for this depot.
*/
unsigned int stack_depot_fetch(depot_stack_handle_t handle,
unsigned long **entries)
{
union handle_parts parts = { .handle = handle };
void *slab;
size_t offset = parts.offset << STACK_ALLOC_ALIGN;
struct stack_record *stack;

*entries = NULL;
if (!handle)
return 0;

if (parts.slabindex > depot_index) {
WARN(1, "slab index %d out of bounds (%d) for stack id %08x\n",
parts.slabindex, depot_index, handle);
return 0;
}
slab = stack_slabs[parts.slabindex];
if (!slab)
return 0;
stack = slab + offset;

*entries = stack->entries;
return stack->size;
}
EXPORT_SYMBOL_GPL(stack_depot_fetch);

/**
* stack_depot_print - print stack entries from a depot
*
* @stack: Stack depot handle which was returned from
* stack_depot_save().
*
*/
void stack_depot_print(depot_stack_handle_t stack)
{
unsigned long *entries;
unsigned int nr_entries;

nr_entries = stack_depot_fetch(stack, &entries);
if (nr_entries > 0)
stack_trace_print(entries, nr_entries, 0);
}
EXPORT_SYMBOL_GPL(stack_depot_print);

/**
* stack_depot_snprint - print stack entries from a depot into a buffer
*
* @handle: Stack depot handle which was 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)
{
unsigned long *entries;
unsigned int nr_entries;

nr_entries = stack_depot_fetch(handle, &entries);
return nr_entries ? stack_trace_snprint(buf, size, entries, nr_entries,
spaces) : 0;
}
EXPORT_SYMBOL_GPL(stack_depot_snprint);

unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle)
{
union handle_parts parts = { .handle = handle };

return parts.extra;
}
EXPORT_SYMBOL(stack_depot_get_extra_bits);

0 comments on commit 15ef6a9

Please sign in to comment.