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lib/stackdepot: annotate init and early init functions

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Add comments to stack_depot_early_init and stack_depot_init to explain
certain parts of their implementation.

Also add a pr_info message to stack_depot_early_init similar to the one
in stack_depot_init.

Also move the scale variable in stack_depot_init to the scope where it
is being used.

Link: https://lkml.kernel.org/r/d17fbfbd4d73f38686c5e3d4824a6d62047213a1.1676063693.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 2023-02-10 22:15:53 +01:00 committed by Andrew Morton
parent 735df3c3a3
commit df225c877d
1 changed files with 21 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
lib/stackdepot.c
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@ -115,24 +115,34 @@ void __init stack_depot_request_early_init(void)
__stack_depot_early_init_requested = true;
}
/* Allocates a hash table via memblock. Can only be used during early boot. */
int __init stack_depot_early_init(void)
{
unsigned long entries = 0;
/* This is supposed to be called only once, from mm_init() */
/* This function must be called only once, from mm_init(). */
if (WARN_ON(__stack_depot_early_init_passed))
return 0;
__stack_depot_early_init_passed = true;
/*
* If KASAN is enabled, use the maximum order: KASAN is frequently used
* in fuzzing scenarios, which leads to a large number of different
* stack traces being stored in stack depot.
*/
if (kasan_enabled() && !stack_hash_order)
stack_hash_order = STACK_HASH_ORDER_MAX;
if (!__stack_depot_early_init_requested || stack_depot_disabled)
return 0;
/*
* If stack_hash_order is not set, leave entries as 0 to rely on the
* automatic calculations performed by alloc_large_system_hash.
*/
if (stack_hash_order)
entries = 1UL << stack_hash_order;
entries = 1UL << stack_hash_order;
pr_info("allocating hash table via alloc_large_system_hash\n");
stack_table = alloc_large_system_hash("stackdepot",
sizeof(struct stack_record *),
entries,
@ -142,7 +152,6 @@ int __init stack_depot_early_init(void)
&stack_hash_mask,
1UL << STACK_HASH_ORDER_MIN,
1UL << STACK_HASH_ORDER_MAX);
if (!stack_table) {
pr_err("hash table allocation failed, disabling\n");
stack_depot_disabled = true;
@ -152,6 +161,7 @@ int __init stack_depot_early_init(void)
return 0;
}
/* Allocates a hash table via kvcalloc. Can be used after boot. */
int stack_depot_init(void)
{
static DEFINE_MUTEX(stack_depot_init_mutex);
@ -160,11 +170,16 @@ int stack_depot_init(void)
mutex_lock(&stack_depot_init_mutex);
if (!stack_depot_disabled && !stack_table) {
unsigned long entries;
int scale = STACK_HASH_SCALE;
/*
* Similarly to stack_depot_early_init, use stack_hash_order
* if assigned, and rely on automatic scaling otherwise.
*/
if (stack_hash_order) {
entries = 1UL << stack_hash_order;
} else {
int scale = STACK_HASH_SCALE;
entries = nr_free_buffer_pages();
entries = roundup_pow_of_two(entries);
@ -179,7 +194,7 @@ int stack_depot_init(void)
if (entries > 1UL << STACK_HASH_ORDER_MAX)
entries = 1UL << STACK_HASH_ORDER_MAX;
pr_info("allocating hash table of %lu entries with kvcalloc\n",
pr_info("allocating hash table of %lu entries via kvcalloc\n",
entries);
stack_table = kvcalloc(entries, sizeof(struct stack_record *), GFP_KERNEL);
if (!stack_table) {