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ANDROID: binder: remove proc waitqueue 

Removes the process waitqueue, so that threads
can only wait on the thread waitqueue. Whenever
there is process work to do, pick a thread and
wake it up. Having the caller pick a thread is
helpful for things like priority inheritance.

This also fixes an issue with using epoll(),
since we no longer have to block on different
waitqueues.

Signed-off-by: Martijn Coenen <maco@android.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Martijn Coenen 2017-08-31 10:04:18 +02:00 committed by Greg Kroah-Hartman
parent 8ef4665aa1
commit 1b77e9dcc3
1 changed files with 182 additions and 75 deletions
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257
drivers/android/binder.c
View File

@ -28,10 +28,10 @@
* binder_node_lock() and binder_node_unlock() are
* used to acq/rel
* 3) proc->inner_lock : protects the thread and node lists
* (proc->threads, proc->nodes) and all todo lists associated
* with the binder_proc (proc->todo, thread->todo,
* proc->delivered_death and node->async_todo), as well as
* thread->transaction_stack
* (proc->threads, proc->waiting_threads, proc->nodes)
* and all todo lists associated with the binder_proc
* (proc->todo, thread->todo, proc->delivered_death and
* node->async_todo), as well as thread->transaction_stack
* binder_inner_proc_lock() and binder_inner_proc_unlock()
* are used to acq/rel
*
@ -475,6 +475,8 @@ enum binder_deferred_state {
* (protected by @outer_lock)
* @refs_by_node: rbtree of refs ordered by ref->node
* (protected by @outer_lock)
* @waiting_threads: threads currently waiting for proc work
* (protected by @inner_lock)
* @pid PID of group_leader of process
* (invariant after initialized)
* @tsk task_struct for group_leader of process
@ -504,8 +506,6 @@ enum binder_deferred_state {
* (protected by @inner_lock)
* @requested_threads_started: number binder threads started
* (protected by @inner_lock)
* @ready_threads: number of threads waiting for proc work
* (protected by @inner_lock)
* @tmp_ref: temporary reference to indicate proc is in use
* (protected by @inner_lock)
* @default_priority: default scheduler priority
@ -526,6 +526,7 @@ struct binder_proc {
struct rb_root nodes;
struct rb_root refs_by_desc;
struct rb_root refs_by_node;
struct list_head waiting_threads;
int pid;
struct task_struct *tsk;
struct files_struct *files;
@ -540,7 +541,6 @@ struct binder_proc {
int max_threads;
int requested_threads;
int requested_threads_started;
int ready_threads;
int tmp_ref;
long default_priority;
struct dentry *debugfs_entry;
@ -556,6 +556,7 @@ enum {
BINDER_LOOPER_STATE_EXITED = 0x04,
BINDER_LOOPER_STATE_INVALID = 0x08,
BINDER_LOOPER_STATE_WAITING = 0x10,
BINDER_LOOPER_STATE_POLL = 0x20,
};
/**
@ -564,6 +565,8 @@ enum {
* (invariant after initialization)
* @rb_node: element for proc->threads rbtree
* (protected by @proc->inner_lock)
* @waiting_thread_node: element for @proc->waiting_threads list
* (protected by @proc->inner_lock)
* @pid: PID for this thread
* (invariant after initialization)
* @looper: bitmap of looping state
@ -593,6 +596,7 @@ enum {
struct binder_thread {
struct binder_proc *proc;
struct rb_node rb_node;
struct list_head waiting_thread_node;
int pid;
int looper; /* only modified by this thread */
bool looper_need_return; /* can be written by other thread */
@ -920,6 +924,86 @@ static long task_close_fd(struct binder_proc *proc, unsigned int fd)
return retval;
}
static bool binder_has_work_ilocked(struct binder_thread *thread,
bool do_proc_work)
{
return !binder_worklist_empty_ilocked(&thread->todo) ||
thread->looper_need_return ||
(do_proc_work &&
!binder_worklist_empty_ilocked(&thread->proc->todo));
}
static bool binder_has_work(struct binder_thread *thread, bool do_proc_work)
{
bool has_work;
binder_inner_proc_lock(thread->proc);
has_work = binder_has_work_ilocked(thread, do_proc_work);
binder_inner_proc_unlock(thread->proc);
return has_work;
}
static bool binder_available_for_proc_work_ilocked(struct binder_thread *thread)
{
return !thread->transaction_stack &&
binder_worklist_empty_ilocked(&thread->todo) &&
(thread->looper & (BINDER_LOOPER_STATE_ENTERED |
BINDER_LOOPER_STATE_REGISTERED));
}
static void binder_wakeup_poll_threads_ilocked(struct binder_proc *proc,
bool sync)
{
struct rb_node *n;
struct binder_thread *thread;
for (n = rb_first(&proc->threads); n != NULL; n = rb_next(n)) {
thread = rb_entry(n, struct binder_thread, rb_node);
if (thread->looper & BINDER_LOOPER_STATE_POLL &&
binder_available_for_proc_work_ilocked(thread)) {
if (sync)
wake_up_interruptible_sync(&thread->wait);
else
wake_up_interruptible(&thread->wait);
}
}
}
static void binder_wakeup_proc_ilocked(struct binder_proc *proc, bool sync)
{
struct binder_thread *thread;
BUG_ON(!spin_is_locked(&proc->inner_lock));
thread = list_first_entry_or_null(&proc->waiting_threads,
struct binder_thread,
waiting_thread_node);
if (thread) {
list_del_init(&thread->waiting_thread_node);
if (sync)
wake_up_interruptible_sync(&thread->wait);
else
wake_up_interruptible(&thread->wait);
return;
}
/* Didn't find a thread waiting for proc work; this can happen
* in two scenarios:
* 1. All threads are busy handling transactions
* In that case, one of those threads should call back into
* the kernel driver soon and pick up this work.
* 2. Threads are using the (e)poll interface, in which case
* they may be blocked on the waitqueue without having been
* added to waiting_threads. For this case, we just iterate
* over all threads not handling transaction work, and
* wake them all up. We wake all because we don't know whether
* a thread that called into (e)poll is handling non-binder
* work currently.
*/
binder_wakeup_poll_threads_ilocked(proc, sync);
}
static void binder_set_nice(long nice)
{
long min_nice;
@ -1138,7 +1222,7 @@ static bool binder_dec_node_nilocked(struct binder_node *node,
if (proc && (node->has_strong_ref || node->has_weak_ref)) {
if (list_empty(&node->work.entry)) {
binder_enqueue_work_ilocked(&node->work, &proc->todo);
wake_up_interruptible(&node->proc->wait);
binder_wakeup_proc_ilocked(proc, false);
}
} else {
if (hlist_empty(&node->refs) && !node->local_strong_refs &&
@ -2399,7 +2483,6 @@ static void binder_transaction(struct binder_proc *proc,
struct binder_thread *target_thread = NULL;
struct binder_node *target_node = NULL;
struct list_head *target_list;
wait_queue_head_t *target_wait;
struct binder_transaction *in_reply_to = NULL;
struct binder_transaction_log_entry *e;
uint32_t return_error = 0;
@ -2409,6 +2492,7 @@ static void binder_transaction(struct binder_proc *proc,
binder_size_t last_fixup_min_off = 0;
struct binder_context *context = proc->context;
int t_debug_id = atomic_inc_return(&binder_last_id);
bool wakeup_for_proc_work = false;
e = binder_transaction_log_add(&binder_transaction_log);
e->debug_id = t_debug_id;
@ -2572,10 +2656,9 @@ static void binder_transaction(struct binder_proc *proc,
if (target_thread) {
e->to_thread = target_thread->pid;
target_list = &target_thread->todo;
target_wait = &target_thread->wait;
} else {
target_list = &target_proc->todo;
target_wait = &target_proc->wait;
wakeup_for_proc_work = true;
}
e->to_proc = target_proc->pid;
@ -2882,7 +2965,7 @@ static void binder_transaction(struct binder_proc *proc,
binder_node_lock(target_node);
if (target_node->has_async_transaction) {
target_list = &target_node->async_todo;
target_wait = NULL;
wakeup_for_proc_work = false;
} else
target_node->has_async_transaction = 1;
/*
@ -2901,11 +2984,13 @@ static void binder_transaction(struct binder_proc *proc,
binder_inner_proc_unlock(target_proc);
binder_node_unlock(target_node);
}
if (target_wait) {
if (reply || !(tr->flags & TF_ONE_WAY))
wake_up_interruptible_sync(target_wait);
else
wake_up_interruptible(target_wait);
if (target_thread) {
wake_up_interruptible_sync(&target_thread->wait);
} else if (wakeup_for_proc_work) {
binder_inner_proc_lock(target_proc);
binder_wakeup_proc_ilocked(target_proc,
!(tr->flags & TF_ONE_WAY));
binder_inner_proc_unlock(target_proc);
}
if (target_thread)
binder_thread_dec_tmpref(target_thread);
@ -3345,12 +3430,14 @@ static int binder_thread_write(struct binder_proc *proc,
&ref->death->work,
&thread->todo);
else {
binder_enqueue_work(
proc,
binder_inner_proc_lock(proc);
binder_enqueue_work_ilocked(
&ref->death->work,
&proc->todo);
wake_up_interruptible(
&proc->wait);
binder_wakeup_proc_ilocked(
proc,
false);
binder_inner_proc_unlock(proc);
}
}
} else {
@ -3385,8 +3472,9 @@ static int binder_thread_write(struct binder_proc *proc,
binder_enqueue_work_ilocked(
&death->work,
&proc->todo);
wake_up_interruptible(
&proc->wait);
binder_wakeup_proc_ilocked(
proc,
false);
}
} else {
BUG_ON(death->work.type != BINDER_WORK_DEAD_BINDER);
@ -3441,7 +3529,8 @@ static int binder_thread_write(struct binder_proc *proc,
binder_enqueue_work_ilocked(
&death->work,
&proc->todo);
wake_up_interruptible(&proc->wait);
binder_wakeup_proc_ilocked(
proc, false);
}
}
binder_inner_proc_unlock(proc);
@ -3468,13 +3557,6 @@ static void binder_stat_br(struct binder_proc *proc,
}
}
static int binder_has_proc_work(struct binder_proc *proc,
struct binder_thread *thread)
{
return !binder_worklist_empty(proc, &proc->todo) ||
thread->looper_need_return;
}
static int binder_has_thread_work(struct binder_thread *thread)
{
return !binder_worklist_empty(thread->proc, &thread->todo) ||
@ -3512,6 +3594,38 @@ static int binder_put_node_cmd(struct binder_proc *proc,
return 0;
}
static int binder_wait_for_work(struct binder_thread *thread,
bool do_proc_work)
{
DEFINE_WAIT(wait);
struct binder_proc *proc = thread->proc;
int ret = 0;
freezer_do_not_count();
binder_inner_proc_lock(proc);
for (;;) {
prepare_to_wait(&thread->wait, &wait, TASK_INTERRUPTIBLE);
if (binder_has_work_ilocked(thread, do_proc_work))
break;
if (do_proc_work)
list_add(&thread->waiting_thread_node,
&proc->waiting_threads);
binder_inner_proc_unlock(proc);
schedule();
binder_inner_proc_lock(proc);
list_del_init(&thread->waiting_thread_node);
if (signal_pending(current)) {
ret = -ERESTARTSYS;
break;
}
}
finish_wait(&thread->wait, &wait);
binder_inner_proc_unlock(proc);
freezer_count();
return ret;
}
static int binder_thread_read(struct binder_proc *proc,
struct binder_thread *thread,
binder_uintptr_t binder_buffer, size_t size,
@ -3532,10 +3646,7 @@ static int binder_thread_read(struct binder_proc *proc,
retry:
binder_inner_proc_lock(proc);
wait_for_proc_work = thread->transaction_stack == NULL &&
binder_worklist_empty_ilocked(&thread->todo);
if (wait_for_proc_work)
proc->ready_threads++;
wait_for_proc_work = binder_available_for_proc_work_ilocked(thread);
binder_inner_proc_unlock(proc);
thread->looper |= BINDER_LOOPER_STATE_WAITING;
@ -3552,23 +3663,15 @@ static int binder_thread_read(struct binder_proc *proc,
binder_stop_on_user_error < 2);
}
binder_set_nice(proc->default_priority);
if (non_block) {
if (!binder_has_proc_work(proc, thread))
ret = -EAGAIN;
} else
ret = wait_event_freezable_exclusive(proc->wait, binder_has_proc_work(proc, thread));
} else {
if (non_block) {
if (!binder_has_thread_work(thread))
ret = -EAGAIN;
} else
ret = wait_event_freezable(thread->wait, binder_has_thread_work(thread));
}
binder_inner_proc_lock(proc);
if (wait_for_proc_work)
proc->ready_threads--;
binder_inner_proc_unlock(proc);
if (non_block) {
if (!binder_has_work(thread, wait_for_proc_work))
ret = -EAGAIN;
} else {
ret = binder_wait_for_work(thread, wait_for_proc_work);
}
thread->looper &= ~BINDER_LOOPER_STATE_WAITING;
if (ret)
@ -3854,7 +3957,8 @@ static int binder_thread_read(struct binder_proc *proc,
*consumed = ptr - buffer;
binder_inner_proc_lock(proc);
if (proc->requested_threads + proc->ready_threads == 0 &&
if (proc->requested_threads == 0 &&
list_empty(&thread->proc->waiting_threads) &&
proc->requested_threads_started < proc->max_threads &&
(thread->looper & (BINDER_LOOPER_STATE_REGISTERED |
BINDER_LOOPER_STATE_ENTERED)) /* the user-space code fails to */
@ -3965,7 +4069,7 @@ static struct binder_thread *binder_get_thread_ilocked(
thread->return_error.cmd = BR_OK;
thread->reply_error.work.type = BINDER_WORK_RETURN_ERROR;
thread->reply_error.cmd = BR_OK;
INIT_LIST_HEAD(&new_thread->waiting_thread_node);
return thread;
}
@ -4078,28 +4182,24 @@ static unsigned int binder_poll(struct file *filp,
{
struct binder_proc *proc = filp->private_data;
struct binder_thread *thread = NULL;
int wait_for_proc_work;
bool wait_for_proc_work;
thread = binder_get_thread(proc);
binder_inner_proc_lock(thread->proc);
wait_for_proc_work = thread->transaction_stack == NULL &&
binder_worklist_empty_ilocked(&thread->todo);
thread->looper |= BINDER_LOOPER_STATE_POLL;
wait_for_proc_work = binder_available_for_proc_work_ilocked(thread);
binder_inner_proc_unlock(thread->proc);
if (wait_for_proc_work) {
if (binder_has_proc_work(proc, thread))
return POLLIN;
poll_wait(filp, &proc->wait, wait);
if (binder_has_proc_work(proc, thread))
return POLLIN;
} else {
if (binder_has_thread_work(thread))
return POLLIN;
poll_wait(filp, &thread->wait, wait);
if (binder_has_thread_work(thread))
return POLLIN;
}
if (binder_has_work(thread, wait_for_proc_work))
return POLLIN;
poll_wait(filp, &thread->wait, wait);
if (binder_has_thread_work(thread))
return POLLIN;
return 0;
}
@ -4146,8 +4246,10 @@ static int binder_ioctl_write_read(struct file *filp,
&bwr.read_consumed,
filp->f_flags & O_NONBLOCK);
trace_binder_read_done(ret);
if (!binder_worklist_empty(proc, &proc->todo))
wake_up_interruptible(&proc->wait);
binder_inner_proc_lock(proc);
if (!binder_worklist_empty_ilocked(&proc->todo))
binder_wakeup_proc_ilocked(proc, false);
binder_inner_proc_unlock(proc);
if (ret < 0) {
if (copy_to_user(ubuf, &bwr, sizeof(bwr)))
ret = -EFAULT;
@ -4389,7 +4491,6 @@ static int binder_open(struct inode *nodp, struct file *filp)
get_task_struct(current->group_leader);
proc->tsk = current->group_leader;
INIT_LIST_HEAD(&proc->todo);
init_waitqueue_head(&proc->wait);
proc->default_priority = task_nice(current);
binder_dev = container_of(filp->private_data, struct binder_device,
miscdev);
@ -4399,6 +4500,7 @@ static int binder_open(struct inode *nodp, struct file *filp)
binder_stats_created(BINDER_STAT_PROC);
proc->pid = current->group_leader->pid;
INIT_LIST_HEAD(&proc->delivered_death);
INIT_LIST_HEAD(&proc->waiting_threads);
filp->private_data = proc;
mutex_lock(&binder_procs_lock);
@ -4450,7 +4552,6 @@ static void binder_deferred_flush(struct binder_proc *proc)
}
}
binder_inner_proc_unlock(proc);
wake_up_interruptible_all(&proc->wait);
binder_debug(BINDER_DEBUG_OPEN_CLOSE,
"binder_flush: %d woke %d threads\n", proc->pid,
@ -4519,7 +4620,7 @@ static int binder_node_release(struct binder_node *node, int refs)
ref->death->work.type = BINDER_WORK_DEAD_BINDER;
binder_enqueue_work_ilocked(&ref->death->work,
&ref->proc->todo);
wake_up_interruptible(&ref->proc->wait);
binder_wakeup_proc_ilocked(ref->proc, false);
binder_inner_proc_unlock(ref->proc);
}
@ -5007,23 +5108,29 @@ static void print_binder_proc_stats(struct seq_file *m,
struct binder_proc *proc)
{
struct binder_work *w;
struct binder_thread *thread;
struct rb_node *n;
int count, strong, weak;
int count, strong, weak, ready_threads;
size_t free_async_space =
binder_alloc_get_free_async_space(&proc->alloc);
seq_printf(m, "proc %d\n", proc->pid);
seq_printf(m, "context %s\n", proc->context->name);
count = 0;
ready_threads = 0;
binder_inner_proc_lock(proc);
for (n = rb_first(&proc->threads); n != NULL; n = rb_next(n))
count++;
list_for_each_entry(thread, &proc->waiting_threads, waiting_thread_node)
ready_threads++;
seq_printf(m, " threads: %d\n", count);
seq_printf(m, " requested threads: %d+%d/%d\n"
" ready threads %d\n"
" free async space %zd\n", proc->requested_threads,
proc->requested_threads_started, proc->max_threads,
proc->ready_threads,
ready_threads,
free_async_space);
count = 0;
for (n = rb_first(&proc->nodes); n != NULL; n = rb_next(n))