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/*
* Copyright (C) 2017 The LineageOS Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "bfqio"
#include <errno.h>
#include <fcntl.h>
#include <cutils/iosched_policy.h>
#include <log/log.h>
#include <pthread.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
static int __rtio_cgroup_supported = -1;
static pthread_once_t __rtio_init_once = PTHREAD_ONCE_INIT;
static void __initialize_rtio(void) {
if (!access("/dev/bfqio/tasks", W_OK) || !access("/dev/bfqio/rt-display/tasks", W_OK)) {
__rtio_cgroup_supported = 1;
} else {
__rtio_cgroup_supported = 0;
}
}
int android_set_rt_ioprio(int tid, int rt) {
int fd = -1, rc = -1;
pthread_once(&__rtio_init_once, __initialize_rtio);
if (__rtio_cgroup_supported != 1) {
return -1;
}
if (rt) {
fd = open("/dev/bfqio/rt-display/tasks", O_WRONLY | O_CLOEXEC);
} else {
fd = open("/dev/bfqio/tasks", O_WRONLY | O_CLOEXEC);
}
if (fd < 0) {
return -1;
}
#ifdef HAVE_GETTID
if (tid == 0) {
tid = gettid();
}
#endif
// specialized itoa -- works for tid > 0
char text[22];
char *end = text + sizeof(text) - 1;
char *ptr = end;
*ptr = '\0';
while (tid > 0) {
*--ptr = '0' + (tid % 10);
tid = tid / 10;
}
rc = write(fd, ptr, end - ptr);
if (rc < 0) {
/*
* If the thread is in the process of exiting,
* don't flag an error
*/
if (errno == ESRCH) {
rc = 0;
} else {
SLOGV("android_set_rt_ioprio failed to write '%s' (%s); fd=%d\n",
ptr, strerror(errno), fd);
}
}
close(fd);
return rc;
}