Commit df225c87 authored by Andrey Konovalov's avatar Andrey Konovalov Committed by Andrew Morton
Browse files

lib/stackdepot: annotate init and early init functions 

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: default avatarAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: default avatarAlexander Potapenko <glider@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 735df3c3

lib/stackdepot.c

+21 −6
Original line number Diff line number Diff line
@@ -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;

	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) {