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// SPDX-License-Identifier: GPL-2.0
#include "comm.h"
#include <errno.h>
#include <string.h>
#include <internal/rc_check.h>
#include <linux/refcount.h>
#include <linux/zalloc.h>
#include "rwsem.h"
DECLARE_RC_STRUCT(comm_str) {
refcount_t refcnt;
char str[];
};
static struct comm_strs {
struct rw_semaphore lock;
struct comm_str **strs;
int num_strs;
int capacity;
} _comm_strs;
static void comm_strs__remove_if_last(struct comm_str *cs);
static void comm_strs__init(void)
{
init_rwsem(&_comm_strs.lock);
_comm_strs.capacity = 16;
_comm_strs.num_strs = 0;
_comm_strs.strs = calloc(16, sizeof(*_comm_strs.strs));
}
static struct comm_strs *comm_strs__get(void)
{
static pthread_once_t comm_strs_type_once = PTHREAD_ONCE_INIT;
pthread_once(&comm_strs_type_once, comm_strs__init);
return &_comm_strs;
}
static refcount_t *comm_str__refcnt(struct comm_str *cs)
{
return &RC_CHK_ACCESS(cs)->refcnt;
}
static const char *comm_str__str(const struct comm_str *cs)
{
return &RC_CHK_ACCESS(cs)->str[0];
}
static struct comm_str *comm_str__get(struct comm_str *cs)
{
struct comm_str *result;
if (RC_CHK_GET(result, cs))
refcount_inc_not_zero(comm_str__refcnt(cs));
return result;
}
static void comm_str__put(struct comm_str *cs)
{
if (!cs)
return;
if (refcount_dec_and_test(comm_str__refcnt(cs))) {
RC_CHK_FREE(cs);
} else {
if (refcount_read(comm_str__refcnt(cs)) == 1)
comm_strs__remove_if_last(cs);
RC_CHK_PUT(cs);
}
}
static struct comm_str *comm_str__new(const char *str)
{
struct comm_str *result = NULL;
RC_STRUCT(comm_str) *cs;
cs = malloc(sizeof(*cs) + strlen(str) + 1);
if (ADD_RC_CHK(result, cs)) {
refcount_set(comm_str__refcnt(result), 1);
strcpy(&cs->str[0], str);
}
return result;
}
static int comm_str__search(const void *_key, const void *_member)
{
const char *key = _key;
const struct comm_str *member = *(const struct comm_str * const *)_member;
return strcmp(key, comm_str__str(member));
}
static void comm_strs__remove_if_last(struct comm_str *cs)
{
struct comm_strs *comm_strs = comm_strs__get();
down_write(&comm_strs->lock);
/*
* Are there only references from the array, if so remove the array
* reference under the write lock so that we don't race with findnew.
*/
if (refcount_read(comm_str__refcnt(cs)) == 1) {
struct comm_str **entry;
entry = bsearch(comm_str__str(cs), comm_strs->strs, comm_strs->num_strs,
sizeof(struct comm_str *), comm_str__search);
comm_str__put(*entry);
for (int i = entry - comm_strs->strs; i < comm_strs->num_strs - 1; i++)
comm_strs->strs[i] = comm_strs->strs[i + 1];
comm_strs->num_strs--;
}
up_write(&comm_strs->lock);
}
static struct comm_str *__comm_strs__find(struct comm_strs *comm_strs, const char *str)
{
struct comm_str **result;
result = bsearch(str, comm_strs->strs, comm_strs->num_strs, sizeof(struct comm_str *),
comm_str__search);
if (!result)
return NULL;
return comm_str__get(*result);
}
static struct comm_str *comm_strs__findnew(const char *str)
{
struct comm_strs *comm_strs = comm_strs__get();
struct comm_str *result;
if (!comm_strs)
return NULL;
down_read(&comm_strs->lock);
result = __comm_strs__find(comm_strs, str);
up_read(&comm_strs->lock);
if (result)
return result;
down_write(&comm_strs->lock);
result = __comm_strs__find(comm_strs, str);
if (!result) {
if (comm_strs->num_strs == comm_strs->capacity) {
struct comm_str **tmp;
tmp = reallocarray(comm_strs->strs,
comm_strs->capacity + 16,
sizeof(*comm_strs->strs));
if (!tmp) {
up_write(&comm_strs->lock);
return NULL;
}
comm_strs->strs = tmp;
comm_strs->capacity += 16;
}
result = comm_str__new(str);
if (result) {
int low = 0, high = comm_strs->num_strs - 1;
int insert = comm_strs->num_strs; /* Default to inserting at the end. */
while (low <= high) {
int mid = low + (high - low) / 2;
int cmp = strcmp(comm_str__str(comm_strs->strs[mid]), str);
if (cmp < 0) {
low = mid + 1;
} else {
high = mid - 1;
insert = mid;
}
}
memmove(&comm_strs->strs[insert + 1], &comm_strs->strs[insert],
(comm_strs->num_strs - insert) * sizeof(struct comm_str *));
comm_strs->num_strs++;
comm_strs->strs[insert] = result;
}
}
up_write(&comm_strs->lock);
return comm_str__get(result);
}
struct comm *comm__new(const char *str, u64 timestamp, bool exec)
{
struct comm *comm = zalloc(sizeof(*comm));
if (!comm)
return NULL;
comm->start = timestamp;
comm->exec = exec;
comm->comm_str = comm_strs__findnew(str);
if (!comm->comm_str) {
free(comm);
return NULL;
}
return comm;
}
int comm__override(struct comm *comm, const char *str, u64 timestamp, bool exec)
{
struct comm_str *new, *old = comm->comm_str;
new = comm_strs__findnew(str);
if (!new)
return -ENOMEM;
comm_str__put(old);
comm->comm_str = new;
comm->start = timestamp;
if (exec)
comm->exec = true;
return 0;
}
void comm__free(struct comm *comm)
{
comm_str__put(comm->comm_str);
free(comm);
}
const char *comm__str(const struct comm *comm)
{
return comm_str__str(comm->comm_str);
}
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