diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/kunit/device-impl.h | 2 | ||||
| -rw-r--r-- | lib/kunit/device.c | 18 | ||||
| -rw-r--r-- | lib/kunit/executor.c | 4 | ||||
| -rw-r--r-- | lib/kunit/kunit-test.c | 2 | ||||
| -rw-r--r-- | lib/kunit/test.c | 17 | ||||
| -rw-r--r-- | lib/seq_buf.c | 49 | ||||
| -rw-r--r-- | lib/stackdepot.c | 373 |
7 files changed, 330 insertions, 135 deletions
diff --git a/lib/kunit/device-impl.h b/lib/kunit/device-impl.h index 54bd55836405..5fcd48ff0f36 100644 --- a/lib/kunit/device-impl.h +++ b/lib/kunit/device-impl.h @@ -13,5 +13,7 @@ // For internal use only -- registers the kunit_bus. int kunit_bus_init(void); +// For internal use only -- unregisters the kunit_bus. +void kunit_bus_shutdown(void); #endif //_KUNIT_DEVICE_IMPL_H diff --git a/lib/kunit/device.c b/lib/kunit/device.c index f5371287b375..644a38a1f5b1 100644 --- a/lib/kunit/device.c +++ b/lib/kunit/device.c @@ -45,8 +45,8 @@ int kunit_bus_init(void) int error; kunit_bus_device = root_device_register("kunit"); - if (!kunit_bus_device) - return -ENOMEM; + if (IS_ERR(kunit_bus_device)) + return PTR_ERR(kunit_bus_device); error = bus_register(&kunit_bus_type); if (error) @@ -54,6 +54,20 @@ int kunit_bus_init(void) return error; } +/* Unregister the 'kunit_bus' in case the KUnit module is unloaded. */ +void kunit_bus_shutdown(void) +{ + /* Make sure the bus exists before we unregister it. */ + if (IS_ERR_OR_NULL(kunit_bus_device)) + return; + + bus_unregister(&kunit_bus_type); + + root_device_unregister(kunit_bus_device); + + kunit_bus_device = NULL; +} + /* Release a 'fake' KUnit device. */ static void kunit_device_release(struct device *d) { diff --git a/lib/kunit/executor.c b/lib/kunit/executor.c index 717b9599036b..689fff2b2b10 100644 --- a/lib/kunit/executor.c +++ b/lib/kunit/executor.c @@ -146,6 +146,10 @@ void kunit_free_suite_set(struct kunit_suite_set suite_set) kfree(suite_set.start); } +/* + * Filter and reallocate test suites. Must return the filtered test suites set + * allocated at a valid virtual address or NULL in case of error. + */ struct kunit_suite_set kunit_filter_suites(const struct kunit_suite_set *suite_set, const char *filter_glob, diff --git a/lib/kunit/kunit-test.c b/lib/kunit/kunit-test.c index c4259d910356..f7980ef236a3 100644 --- a/lib/kunit/kunit-test.c +++ b/lib/kunit/kunit-test.c @@ -720,7 +720,7 @@ static void kunit_device_cleanup_test(struct kunit *test) long action_was_run = 0; test_device = kunit_device_register(test, "my_device"); - KUNIT_ASSERT_NOT_NULL(test, test_device); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, test_device); /* Add an action to verify cleanup. */ devm_add_action(test_device, test_dev_action, &action_was_run); diff --git a/lib/kunit/test.c b/lib/kunit/test.c index f95d2093a0aa..1d1475578515 100644 --- a/lib/kunit/test.c +++ b/lib/kunit/test.c @@ -17,6 +17,7 @@ #include <linux/panic.h> #include <linux/sched/debug.h> #include <linux/sched.h> +#include <linux/mm.h> #include "debugfs.h" #include "device-impl.h" @@ -801,12 +802,19 @@ static void kunit_module_exit(struct module *mod) }; const char *action = kunit_action(); + /* + * Check if the start address is a valid virtual address to detect + * if the module load sequence has failed and the suite set has not + * been initialized and filtered. + */ + if (!suite_set.start || !virt_addr_valid(suite_set.start)) + return; + if (!action) __kunit_test_suites_exit(mod->kunit_suites, mod->num_kunit_suites); - if (suite_set.start) - kunit_free_suite_set(suite_set); + kunit_free_suite_set(suite_set); } static int kunit_module_notify(struct notifier_block *nb, unsigned long val, @@ -816,12 +824,12 @@ static int kunit_module_notify(struct notifier_block *nb, unsigned long val, switch (val) { case MODULE_STATE_LIVE: + kunit_module_init(mod); break; case MODULE_STATE_GOING: kunit_module_exit(mod); break; case MODULE_STATE_COMING: - kunit_module_init(mod); break; case MODULE_STATE_UNFORMED: break; @@ -920,6 +928,9 @@ static void __exit kunit_exit(void) #ifdef CONFIG_MODULES unregister_module_notifier(&kunit_mod_nb); #endif + + kunit_bus_shutdown(); + kunit_debugfs_cleanup(); } module_exit(kunit_exit); diff --git a/lib/seq_buf.c b/lib/seq_buf.c index 010c730ca7fc..f3f3436d60a9 100644 --- a/lib/seq_buf.c +++ b/lib/seq_buf.c @@ -13,16 +13,26 @@ * seq_buf_init() more than once to reset the seq_buf to start * from scratch. */ -#include <linux/uaccess.h> -#include <linux/seq_file.h> + +#include <linux/bug.h> +#include <linux/err.h> +#include <linux/export.h> +#include <linux/hex.h> +#include <linux/minmax.h> +#include <linux/printk.h> #include <linux/seq_buf.h> +#include <linux/seq_file.h> +#include <linux/sprintf.h> +#include <linux/string.h> +#include <linux/types.h> +#include <linux/uaccess.h> /** * seq_buf_can_fit - can the new data fit in the current buffer? * @s: the seq_buf descriptor * @len: The length to see if it can fit in the current buffer * - * Returns true if there's enough unused space in the seq_buf buffer + * Returns: true if there's enough unused space in the seq_buf buffer * to fit the amount of new data according to @len. */ static bool seq_buf_can_fit(struct seq_buf *s, size_t len) @@ -35,7 +45,7 @@ static bool seq_buf_can_fit(struct seq_buf *s, size_t len) * @m: the seq_file descriptor that is the destination * @s: the seq_buf descriptor that is the source. * - * Returns zero on success, non zero otherwise + * Returns: zero on success, non-zero otherwise. */ int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s) { @@ -50,9 +60,9 @@ int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s) * @fmt: printf format string * @args: va_list of arguments from a printf() type function * - * Writes a vnprintf() format into the sequencce buffer. + * Writes a vnprintf() format into the sequence buffer. * - * Returns zero on success, -1 on overflow. + * Returns: zero on success, -1 on overflow. */ int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args) { @@ -78,7 +88,7 @@ int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args) * * Writes a printf() format into the sequence buffer. * - * Returns zero on success, -1 on overflow. + * Returns: zero on success, -1 on overflow. */ int seq_buf_printf(struct seq_buf *s, const char *fmt, ...) { @@ -94,12 +104,12 @@ int seq_buf_printf(struct seq_buf *s, const char *fmt, ...) EXPORT_SYMBOL_GPL(seq_buf_printf); /** - * seq_buf_do_printk - printk seq_buf line by line + * seq_buf_do_printk - printk() seq_buf line by line * @s: seq_buf descriptor * @lvl: printk level * * printk()-s a multi-line sequential buffer line by line. The function - * makes sure that the buffer in @s is nul terminated and safe to read + * makes sure that the buffer in @s is NUL-terminated and safe to read * as a string. */ void seq_buf_do_printk(struct seq_buf *s, const char *lvl) @@ -139,7 +149,7 @@ EXPORT_SYMBOL_GPL(seq_buf_do_printk); * This function will take the format and the binary array and finish * the conversion into the ASCII string within the buffer. * - * Returns zero on success, -1 on overflow. + * Returns: zero on success, -1 on overflow. */ int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary) { @@ -167,7 +177,7 @@ int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary) * * Copy a simple string into the sequence buffer. * - * Returns zero on success, -1 on overflow + * Returns: zero on success, -1 on overflow. */ int seq_buf_puts(struct seq_buf *s, const char *str) { @@ -196,7 +206,7 @@ EXPORT_SYMBOL_GPL(seq_buf_puts); * * Copy a single character into the sequence buffer. * - * Returns zero on success, -1 on overflow + * Returns: zero on success, -1 on overflow. */ int seq_buf_putc(struct seq_buf *s, unsigned char c) { @@ -212,7 +222,7 @@ int seq_buf_putc(struct seq_buf *s, unsigned char c) EXPORT_SYMBOL_GPL(seq_buf_putc); /** - * seq_buf_putmem - write raw data into the sequenc buffer + * seq_buf_putmem - write raw data into the sequence buffer * @s: seq_buf descriptor * @mem: The raw memory to copy into the buffer * @len: The length of the raw memory to copy (in bytes) @@ -221,7 +231,7 @@ EXPORT_SYMBOL_GPL(seq_buf_putc); * buffer and a strcpy() would not work. Using this function allows * for such cases. * - * Returns zero on success, -1 on overflow + * Returns: zero on success, -1 on overflow. */ int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len) { @@ -249,7 +259,7 @@ int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len) * raw memory into the buffer it writes its ASCII representation of it * in hex characters. * - * Returns zero on success, -1 on overflow + * Returns: zero on success, -1 on overflow. */ int seq_buf_putmem_hex(struct seq_buf *s, const void *mem, unsigned int len) @@ -297,7 +307,7 @@ int seq_buf_putmem_hex(struct seq_buf *s, const void *mem, * * Write a path name into the sequence buffer. * - * Returns the number of written bytes on success, -1 on overflow + * Returns: the number of written bytes on success, -1 on overflow. */ int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc) { @@ -332,6 +342,7 @@ int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc) * or until it reaches the end of the content in the buffer (@s->len), * whichever comes first. * + * Returns: * On success, it returns a positive number of the number of bytes * it copied. * @@ -382,11 +393,11 @@ int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, size_t start, int cnt) * linebuf size is maximal length for one line. * 32 * 3 - maximum bytes per line, each printed into 2 chars + 1 for * separating space - * 2 - spaces separating hex dump and ascii representation - * 32 - ascii representation + * 2 - spaces separating hex dump and ASCII representation + * 32 - ASCII representation * 1 - terminating '\0' * - * Returns zero on success, -1 on overflow + * Returns: zero on success, -1 on overflow. */ int seq_buf_hex_dump(struct seq_buf *s, const char *prefix_str, int prefix_type, int rowsize, int groupsize, diff --git a/lib/stackdepot.c b/lib/stackdepot.c index a0be5d05c7f0..5caa1f566553 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -14,6 +14,7 @@ #define pr_fmt(fmt) "stackdepot: " fmt +#include <linux/debugfs.h> #include <linux/gfp.h> #include <linux/jhash.h> #include <linux/kernel.h> @@ -21,8 +22,9 @@ #include <linux/list.h> #include <linux/mm.h> #include <linux/mutex.h> -#include <linux/percpu.h> #include <linux/printk.h> +#include <linux/rculist.h> +#include <linux/rcupdate.h> #include <linux/refcount.h> #include <linux/slab.h> #include <linux/spinlock.h> @@ -67,12 +69,28 @@ union handle_parts { }; struct stack_record { - struct list_head list; /* Links in hash table or freelist */ + struct list_head hash_list; /* Links in the hash table */ u32 hash; /* Hash in hash table */ u32 size; /* Number of stored frames */ - union handle_parts handle; + union handle_parts handle; /* Constant after initialization */ refcount_t count; - unsigned long entries[CONFIG_STACKDEPOT_MAX_FRAMES]; /* Frames */ + union { + unsigned long entries[CONFIG_STACKDEPOT_MAX_FRAMES]; /* Frames */ + struct { + /* + * An important invariant of the implementation is to + * only place a stack record onto the freelist iff its + * refcount is zero. Because stack records with a zero + * refcount are never considered as valid, it is safe to + * union @entries and freelist management state below. + * Conversely, as soon as an entry is off the freelist + * and its refcount becomes non-zero, the below must not + * be accessed until being placed back on the freelist. + */ + struct list_head free_list; /* Links in the freelist */ + unsigned long rcu_state; /* RCU cookie */ + }; + }; }; #define DEPOT_STACK_RECORD_SIZE \ @@ -112,8 +130,25 @@ static LIST_HEAD(free_stacks); * yet allocated or if the limit on the number of pools is reached. */ static bool new_pool_required = true; -/* Lock that protects the variables above. */ -static DEFINE_RWLOCK(pool_rwlock); +/* The lock must be held when performing pool or freelist modifications. */ +static DEFINE_RAW_SPINLOCK(pool_lock); + +/* Statistics counters for debugfs. */ +enum depot_counter_id { + DEPOT_COUNTER_ALLOCS, + DEPOT_COUNTER_FREES, + DEPOT_COUNTER_INUSE, + DEPOT_COUNTER_FREELIST_SIZE, + DEPOT_COUNTER_COUNT, +}; +static long counters[DEPOT_COUNTER_COUNT]; +static const char *const counter_names[] = { + [DEPOT_COUNTER_ALLOCS] = "allocations", + [DEPOT_COUNTER_FREES] = "frees", + [DEPOT_COUNTER_INUSE] = "in_use", + [DEPOT_COUNTER_FREELIST_SIZE] = "freelist_size", +}; +static_assert(ARRAY_SIZE(counter_names) == DEPOT_COUNTER_COUNT); static int __init disable_stack_depot(char *str) { @@ -258,14 +293,15 @@ out_unlock: } EXPORT_SYMBOL_GPL(stack_depot_init); -/* Initializes a stack depol pool. */ +/* + * Initializes new stack depot @pool, release all its entries to the freelist, + * and update the list of pools. + */ static void depot_init_pool(void *pool) { int offset; - lockdep_assert_held_write(&pool_rwlock); - - WARN_ON(!list_empty(&free_stacks)); + lockdep_assert_held(&pool_lock); /* Initialize handles and link stack records into the freelist. */ for (offset = 0; offset <= DEPOT_POOL_SIZE - DEPOT_STACK_RECORD_SIZE; @@ -276,18 +312,36 @@ static void depot_init_pool(void *pool) stack->handle.offset = offset >> DEPOT_STACK_ALIGN; stack->handle.extra = 0; - list_add(&stack->list, &free_stacks); + /* + * Stack traces of size 0 are never saved, and we can simply use + * the size field as an indicator if this is a new unused stack + * record in the freelist. + */ + stack->size = 0; + + INIT_LIST_HEAD(&stack->hash_list); + /* + * Add to the freelist front to prioritize never-used entries: + * required in case there are entries in the freelist, but their + * RCU cookie still belongs to the current RCU grace period + * (there can still be concurrent readers). + */ + list_add(&stack->free_list, &free_stacks); + counters[DEPOT_COUNTER_FREELIST_SIZE]++; } /* Save reference to the pool to be used by depot_fetch_stack(). */ stack_pools[pools_num] = pool; - pools_num++; + + /* Pairs with concurrent READ_ONCE() in depot_fetch_stack(). */ + WRITE_ONCE(pools_num, pools_num + 1); + ASSERT_EXCLUSIVE_WRITER(pools_num); } /* Keeps the preallocated memory to be used for a new stack depot pool. */ static void depot_keep_new_pool(void **prealloc) { - lockdep_assert_held_write(&pool_rwlock); + lockdep_assert_held(&pool_lock); /* * If a new pool is already saved or the maximum number of @@ -310,17 +364,16 @@ static void depot_keep_new_pool(void **prealloc) * number of pools is reached. In either case, take note that * keeping another pool is not required. */ - new_pool_required = false; + WRITE_ONCE(new_pool_required, false); } -/* Updates references to the current and the next stack depot pools. */ -static bool depot_update_pools(void **prealloc) +/* + * Try to initialize a new stack depot pool from either a previous or the + * current pre-allocation, and release all its entries to the freelist. + */ +static bool depot_try_init_pool(void **prealloc) { - lockdep_assert_held_write(&pool_rwlock); - - /* Check if we still have objects in the freelist. */ - if (!list_empty(&free_stacks)) - goto out_keep_prealloc; + lockdep_assert_held(&pool_lock); /* Check if we have a new pool saved and use it. */ if (new_pool) { @@ -329,10 +382,9 @@ static bool depot_update_pools(void **prealloc) /* Take note that we might need a new new_pool. */ if (pools_num < DEPOT_MAX_POOLS) - new_pool_required = true; + WRITE_ONCE(new_pool_required, true); - /* Try keeping the preallocated memory for new_pool. */ - goto out_keep_prealloc; + return true; } /* Bail out if we reached the pool limit. */ @@ -349,12 +401,32 @@ static bool depot_update_pools(void **prealloc) } return false; +} + +/* Try to find next free usable entry. */ +static struct stack_record *depot_pop_free(void) +{ + struct stack_record *stack; + + lockdep_assert_held(&pool_lock); + + if (list_empty(&free_stacks)) + return NULL; + + /* + * We maintain the invariant that the elements in front are least + * recently used, and are therefore more likely to be associated with an + * RCU grace period in the past. Consequently it is sufficient to only + * check the first entry. + */ + stack = list_first_entry(&free_stacks, struct stack_record, free_list); + if (stack->size && !poll_state_synchronize_rcu(stack->rcu_state)) + return NULL; + + list_del(&stack->free_list); + counters[DEPOT_COUNTER_FREELIST_SIZE]--; -out_keep_prealloc: - /* Keep the preallocated memory for a new pool if required. */ - if (*prealloc) - depot_keep_new_pool(prealloc); - return true; + return stack; } /* Allocates a new stack in a stack depot pool. */ @@ -363,19 +435,22 @@ depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc) { struct stack_record *stack; - lockdep_assert_held_write(&pool_rwlock); + lockdep_assert_held(&pool_lock); - /* Update current and new pools if required and possible. */ - if (!depot_update_pools(prealloc)) + /* This should already be checked by public API entry points. */ + if (WARN_ON_ONCE(!size)) return NULL; /* Check if we have a stack record to save the stack trace. */ - if (list_empty(&free_stacks)) - return NULL; - - /* Get and unlink the first entry from the freelist. */ - stack = list_first_entry(&free_stacks, struct stack_record, list); - list_del(&stack->list); + stack = depot_pop_free(); + if (!stack) { + /* No usable entries on the freelist - try to refill the freelist. */ + if (!depot_try_init_pool(prealloc)) + return NULL; + stack = depot_pop_free(); + if (WARN_ON(!stack)) + return NULL; + } /* Limit number of saved frames to CONFIG_STACKDEPOT_MAX_FRAMES. */ if (size > CONFIG_STACKDEPOT_MAX_FRAMES) @@ -394,38 +469,80 @@ depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc) */ kmsan_unpoison_memory(stack, DEPOT_STACK_RECORD_SIZE); + counters[DEPOT_COUNTER_ALLOCS]++; + counters[DEPOT_COUNTER_INUSE]++; return stack; } static struct stack_record *depot_fetch_stack(depot_stack_handle_t handle) { + const int pools_num_cached = READ_ONCE(pools_num); union handle_parts parts = { .handle = handle }; void *pool; size_t offset = parts.offset << DEPOT_STACK_ALIGN; struct stack_record *stack; - lockdep_assert_held(&pool_rwlock); + lockdep_assert_not_held(&pool_lock); - if (parts.pool_index > pools_num) { + if (parts.pool_index > pools_num_cached) { WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n", - parts.pool_index, pools_num, handle); + parts.pool_index, pools_num_cached, handle); return NULL; } pool = stack_pools[parts.pool_index]; - if (!pool) + if (WARN_ON(!pool)) return NULL; stack = pool + offset; + if (WARN_ON(!refcount_read(&stack->count))) + return NULL; + return stack; } /* Links stack into the freelist. */ static void depot_free_stack(struct stack_record *stack) { - lockdep_assert_held_write(&pool_rwlock); + unsigned long flags; + + lockdep_assert_not_held(&pool_lock); - list_add(&stack->list, &free_stacks); + raw_spin_lock_irqsave(&pool_lock, flags); + printk_deferred_enter(); + + /* + * Remove the entry from the hash list. Concurrent list traversal may + * still observe the entry, but since the refcount is zero, this entry + * will no longer be considered as valid. + */ + list_del_rcu(&stack->hash_list); + + /* + * Due to being used from constrained contexts such as the allocators, + * NMI, or even RCU itself, stack depot cannot rely on primitives that + * would sleep (such as synchronize_rcu()) or recursively call into + * stack depot again (such as call_rcu()). + * + * Instead, get an RCU cookie, so that we can ensure this entry isn't + * moved onto another list until the next grace period, and concurrent + * RCU list traversal remains safe. + */ + stack->rcu_state = get_state_synchronize_rcu(); + + /* + * Add the entry to the freelist tail, so that older entries are + * considered first - their RCU cookie is more likely to no longer be + * associated with the current grace period. + */ + list_add_tail(&stack->free_list, &free_stacks); + + counters[DEPOT_COUNTER_FREELIST_SIZE]++; + counters[DEPOT_COUNTER_FREES]++; + counters[DEPOT_COUNTER_INUSE]--; + + printk_deferred_exit(); + raw_spin_unlock_irqrestore(&pool_lock, flags); } /* Calculates the hash for a stack. */ @@ -453,22 +570,52 @@ int stackdepot_memcmp(const unsigned long *u1, const unsigned long *u2, /* Finds a stack in a bucket of the hash table. */ static inline struct stack_record *find_stack(struct list_head *bucket, - unsigned long *entries, int size, - u32 hash) + unsigned long *entries, int size, + u32 hash, depot_flags_t flags) { - struct list_head *pos; - struct stack_record *found; + struct stack_record *stack, *ret = NULL; + + /* + * Stack depot may be used from instrumentation that instruments RCU or + * tracing itself; use variant that does not call into RCU and cannot be + * traced. + * + * Note: Such use cases must take care when using refcounting to evict + * unused entries, because the stack record free-then-reuse code paths + * do call into RCU. + */ + rcu_read_lock_sched_notrace(); - lockdep_assert_held(&pool_rwlock); + list_for_each_entry_rcu(stack, bucket, hash_list) { + if (stack->hash != hash || stack->size != size) + continue; + + /* + * This may race with depot_free_stack() accessing the freelist + * management state unioned with @entries. The refcount is zero + * in that case and the below refcount_inc_not_zero() will fail. + */ + if (data_race(stackdepot_memcmp(entries, stack->entries, size))) + continue; + + /* + * Try to increment refcount. If this succeeds, the stack record + * is valid and has not yet been freed. + * + * If STACK_DEPOT_FLAG_GET is not used, it is undefined behavior + * to then call stack_depot_put() later, and we can assume that + * a stack record is never placed back on the freelist. + */ + if ((flags & STACK_DEPOT_FLAG_GET) && !refcount_inc_not_zero(&stack->count)) + continue; - list_for_each(pos, bucket) { - found = list_entry(pos, struct stack_record, list); - if (found->hash == hash && - found->size == size && - !stackdepot_memcmp(entries, found->entries, size)) - return found; + ret = stack; + break; } - return NULL; + + rcu_read_unlock_sched_notrace(); + + return ret; } depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, @@ -482,7 +629,6 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, struct page *page = NULL; void *prealloc = NULL; bool can_alloc = depot_flags & STACK_DEPOT_FLAG_CAN_ALLOC; - bool need_alloc = false; unsigned long flags; u32 hash; @@ -505,31 +651,16 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, hash = hash_stack(entries, nr_entries); bucket = &stack_table[hash & stack_hash_mask]; - read_lock_irqsave(&pool_rwlock, flags); - printk_deferred_enter(); - - /* Fast path: look the stack trace up without full locking. */ - found = find_stack(bucket, entries, nr_entries, hash); - if (found) { - if (depot_flags & STACK_DEPOT_FLAG_GET) - refcount_inc(&found->count); - printk_deferred_exit(); - read_unlock_irqrestore(&pool_rwlock, flags); + /* Fast path: look the stack trace up without locking. */ + found = find_stack(bucket, entries, nr_entries, hash, depot_flags); + if (found) goto exit; - } - - /* Take note if another stack pool needs to be allocated. */ - if (new_pool_required) - need_alloc = true; - - printk_deferred_exit(); - read_unlock_irqrestore(&pool_rwlock, flags); /* * Allocate memory for a new pool if required now: * we won't be able to do that under the lock. */ - if (unlikely(can_alloc && need_alloc)) { + if (unlikely(can_alloc && READ_ONCE(new_pool_required))) { /* * Zero out zone modifiers, as we don't have specific zone * requirements. Keep the flags related to allocation in atomic @@ -543,31 +674,36 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, prealloc = page_address(page); } - write_lock_irqsave(&pool_rwlock, flags); + raw_spin_lock_irqsave(&pool_lock, flags); printk_deferred_enter(); - found = find_stack(bucket, entries, nr_entries, hash); + /* Try to find again, to avoid concurrently inserting duplicates. */ + found = find_stack(bucket, entries, nr_entries, hash, depot_flags); if (!found) { struct stack_record *new = depot_alloc_stack(entries, nr_entries, hash, &prealloc); if (new) { - list_add(&new->list, bucket); + /* + * This releases the stack record into the bucket and + * makes it visible to readers in find_stack(). + */ + list_add_rcu(&new->hash_list, bucket); found = new; } - } else { - if (depot_flags & STACK_DEPOT_FLAG_GET) - refcount_inc(&found->count); + } + + if (prealloc) { /* - * Stack depot already contains this stack trace, but let's - * keep the preallocated memory for future. + * Either stack depot already contains this stack trace, or + * depot_alloc_stack() did not consume the preallocated memory. + * Try to keep the preallocated memory for future. */ - if (prealloc) - depot_keep_new_pool(&prealloc); + depot_keep_new_pool(&prealloc); } printk_deferred_exit(); - write_unlock_irqrestore(&pool_rwlock, flags); + raw_spin_unlock_irqrestore(&pool_lock, flags); exit: if (prealloc) { /* Stack depot didn't use this memory, free it. */ @@ -592,7 +728,6 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle, unsigned long **entries) { struct stack_record *stack; - unsigned long flags; *entries = NULL; /* @@ -604,13 +739,13 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle, if (!handle || stack_depot_disabled) return 0; - read_lock_irqsave(&pool_rwlock, flags); - printk_deferred_enter(); - stack = depot_fetch_stack(handle); - - printk_deferred_exit(); - read_unlock_irqrestore(&pool_rwlock, flags); + /* + * Should never be NULL, otherwise this is a use-after-put (or just a + * corrupt handle). + */ + if (WARN(!stack, "corrupt handle or use after stack_depot_put()")) + return 0; *entries = stack->entries; return stack->size; @@ -620,29 +755,20 @@ EXPORT_SYMBOL_GPL(stack_depot_fetch); void stack_depot_put(depot_stack_handle_t handle) { struct stack_record *stack; - unsigned long flags; if (!handle || stack_depot_disabled) return; - write_lock_irqsave(&pool_rwlock, flags); - printk_deferred_enter(); - stack = depot_fetch_stack(handle); - if (WARN_ON(!stack)) - goto out; - - if (refcount_dec_and_test(&stack->count)) { - /* Unlink stack from the hash table. */ - list_del(&stack->list); + /* + * Should always be able to find the stack record, otherwise this is an + * unbalanced put attempt (or corrupt handle). + */ + if (WARN(!stack, "corrupt handle or unbalanced stack_depot_put()")) + return; - /* Free stack. */ + if (refcount_dec_and_test(&stack->count)) depot_free_stack(stack); - } - -out: - printk_deferred_exit(); - write_unlock_irqrestore(&pool_rwlock, flags); } EXPORT_SYMBOL_GPL(stack_depot_put); @@ -690,3 +816,30 @@ unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle) return parts.extra; } EXPORT_SYMBOL(stack_depot_get_extra_bits); + +static int stats_show(struct seq_file *seq, void *v) +{ + /* + * data race ok: These are just statistics counters, and approximate + * statistics are ok for debugging. + */ + seq_printf(seq, "pools: %d\n", data_race(pools_num)); + for (int i = 0; i < DEPOT_COUNTER_COUNT; i++) + seq_printf(seq, "%s: %ld\n", counter_names[i], data_race(counters[i])); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(stats); + +static int depot_debugfs_init(void) +{ + struct dentry *dir; + + if (stack_depot_disabled) + return 0; + + dir = debugfs_create_dir("stackdepot", NULL); + debugfs_create_file("stats", 0444, dir, NULL, &stats_fops); + return 0; +} +late_initcall(depot_debugfs_init); |