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BACKPORT: FROMGIT: binder: BINDER_FREEZE ioctl

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Frozen tasks can't process binder transactions, so a way is required to
inform transmitting ends of communication failures due to the frozen
state of their receiving counterparts. Additionally, races are possible
between transitions to frozen state and binder transactions enqueued to
a specific process.

Implement BINDER_FREEZE ioctl for user space to inform the binder driver
about the intention to freeze or unfreeze a process. When the ioctl is
called, block the caller until any pending binder transactions toward
the target process are flushed. Return an error to transactions to
processes marked as frozen.

Bug: 180989544
(cherry picked from commit 15949c3cdd97bccdcd45c0c0f6c31058520b6494
 git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git char-misc-testing)
Co-developed-by: Todd Kjos <tkjos@google.com>
Acked-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Marco Ballesio <balejs@google.com>
Signed-off-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Li Li <dualli@google.com>
Link: https://lore.kernel.org/r/20210316011630.1121213-2-dualli@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Change-Id: Ia1b5951cd99eeb98b59e06c3e27d59062dc725f6
urubino
Marco Ballesio 3 years ago committed by Jenna-they-them
parent f8a788477c
commit 963618662e
2 changed files with 111 additions and 10 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 108
      drivers/android/binder.c
  2. 13
      include/uapi/linux/android/binder.h

108
drivers/android/binder.c
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@ -474,9 +474,18 @@ struct binder_priority {
* (protected by binder_deferred_lock)
* @deferred_work: bitmap of deferred work to perform
* (protected by binder_deferred_lock)
* @outstanding_txns: number of transactions to be transmitted before
* processes in freeze_wait are woken up
* (protected by @inner_lock)
* @is_dead: process is dead and awaiting free
* when outstanding transactions are cleaned up
* (protected by @inner_lock)
* @is_frozen: process is frozen and unable to service
* binder transactions
* (protected by @inner_lock)
* @freeze_wait: waitqueue of processes waiting for all outstanding
* transactions to be processed
* (protected by @inner_lock)
* @todo: list of work for this process
* (protected by @inner_lock)
* @stats: per-process binder statistics
@ -520,7 +529,10 @@ struct binder_proc {
const struct cred *cred;
struct hlist_node deferred_work_node;
int deferred_work;
int outstanding_txns;
bool is_dead;
bool is_frozen;
wait_queue_head_t freeze_wait;
struct list_head todo;
struct binder_stats stats;
@ -2098,6 +2110,12 @@ static void binder_free_transaction(struct binder_transaction *t)
if (target_proc) {
binder_inner_proc_lock(target_proc);
target_proc->outstanding_txns--;
if (target_proc->outstanding_txns < 0)
pr_warn("%s: Unexpected outstanding_txns %d\n",
__func__, target_proc->outstanding_txns);
if (!target_proc->outstanding_txns && target_proc->is_frozen)
wake_up_interruptible_all(&target_proc->freeze_wait);
if (t->buffer)
t->buffer->transaction = NULL;
binder_inner_proc_unlock(target_proc);
@ -2848,10 +2866,11 @@ static int binder_fixup_parent(struct binder_transaction *t,
* If the @thread parameter is not NULL, the transaction is always queued
* to the waitlist of that specific thread.
*
* Return: true if the transactions was successfully queued
* false if the target process or thread is dead
* Return: 0 if the transaction was successfully queued
* BR_DEAD_REPLY if the target process or thread is dead
* BR_FROZEN_REPLY if the target process or thread is frozen
*/
static bool binder_proc_transaction(struct binder_transaction *t,
static int binder_proc_transaction(struct binder_transaction *t,
struct binder_proc *proc,
struct binder_thread *thread)
{
@ -2876,10 +2895,12 @@ static bool binder_proc_transaction(struct binder_transaction *t,
binder_inner_proc_lock(proc);
if (proc->is_dead || (thread && thread->is_dead)) {
if (proc->is_frozen || proc->is_dead || (thread && thread->is_dead)) {
bool proc_is_dead = proc->is_dead
|| (thread && thread->is_dead);
binder_inner_proc_unlock(proc);
binder_node_unlock(node);
return false;
return proc_is_dead ? BR_DEAD_REPLY : BR_FROZEN_REPLY;
}
if (!thread && !pending_async)
@ -2898,10 +2919,11 @@ static bool binder_proc_transaction(struct binder_transaction *t,
if (!pending_async)
binder_wakeup_thread_ilocked(proc, thread, !oneway /* sync */);
proc->outstanding_txns++;
binder_inner_proc_unlock(proc);
binder_node_unlock(node);
return true;
return 0;
}
/**
@ -3495,13 +3517,16 @@ static void binder_transaction(struct binder_proc *proc,
if (reply) {
binder_enqueue_thread_work(thread, tcomplete);
binder_inner_proc_lock(target_proc);
if (target_thread->is_dead) {
if (target_thread->is_dead || target_proc->is_frozen) {
return_error = target_proc->is_dead ?
BR_DEAD_REPLY : BR_FROZEN_REPLY;
binder_inner_proc_unlock(target_proc);
goto err_dead_proc_or_thread;
}
BUG_ON(t->buffer->async_transaction != 0);
binder_pop_transaction_ilocked(target_thread, in_reply_to);
binder_enqueue_thread_work_ilocked(target_thread, &t->work);
target_proc->outstanding_txns++;
binder_inner_proc_unlock(target_proc);
wake_up_interruptible_sync(&target_thread->wait);
binder_restore_priority(current, in_reply_to->saved_priority);
@ -3521,7 +3546,9 @@ static void binder_transaction(struct binder_proc *proc,
t->from_parent = thread->transaction_stack;
thread->transaction_stack = t;
binder_inner_proc_unlock(proc);
if (!binder_proc_transaction(t, target_proc, target_thread)) {
return_error = binder_proc_transaction(t,
target_proc, target_thread);
if (return_error) {
binder_inner_proc_lock(proc);
binder_pop_transaction_ilocked(thread, t);
binder_inner_proc_unlock(proc);
@ -3531,7 +3558,8 @@ static void binder_transaction(struct binder_proc *proc,
BUG_ON(target_node == NULL);
BUG_ON(t->buffer->async_transaction != 1);
binder_enqueue_thread_work(thread, tcomplete);
if (!binder_proc_transaction(t, target_proc, NULL))
return_error = binder_proc_transaction(t, target_proc, NULL);
if (return_error)
goto err_dead_proc_or_thread;
}
if (target_thread)
@ -3548,7 +3576,6 @@ static void binder_transaction(struct binder_proc *proc,
return;
err_dead_proc_or_thread:
return_error = BR_DEAD_REPLY;
return_error_line = __LINE__;
binder_dequeue_work(proc, tcomplete);
err_translate_failed:
@ -4657,6 +4684,7 @@ static void binder_free_proc(struct binder_proc *proc)
BUG_ON(!list_empty(&proc->todo));
BUG_ON(!list_empty(&proc->delivered_death));
WARN_ON(proc->outstanding_txns);
device = container_of(proc->context, struct binder_device, context);
if (refcount_dec_and_test(&device->ref)) {
kfree(proc->context->name);
@ -4718,6 +4746,7 @@ static int binder_thread_release(struct binder_proc *proc,
(t->to_thread == thread) ? "in" : "out");
if (t->to_thread == thread) {
t->to_proc->outstanding_txns--;
t->to_proc = NULL;
t->to_thread = NULL;
if (t->buffer) {
@ -5079,6 +5108,63 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
}
break;
}
case BINDER_FREEZE: {
struct binder_freeze_info info;
struct binder_proc *target_proc;
bool found = false;
if (copy_from_user(&info, ubuf, sizeof(info))) {
ret = -EFAULT;
goto err;
}
mutex_lock(&binder_procs_lock);
hlist_for_each_entry(target_proc, &binder_procs, proc_node) {
if (target_proc->pid == info.pid) {
found = true;
binder_inner_proc_lock(target_proc);
target_proc->tmp_ref++;
binder_inner_proc_unlock(target_proc);
break;
}
}
mutex_unlock(&binder_procs_lock);
if (!found) {
ret = -EINVAL;
goto err;
}
if (!info.enable) {
binder_inner_proc_lock(target_proc);
target_proc->is_frozen = false;
binder_inner_proc_unlock(target_proc);
binder_proc_dec_tmpref(target_proc);
break;
}
/*
* Freezing the target. Prevent new transactions by
* setting frozen state. If timeout specified, wait
* for transactions to drain.
*/
binder_inner_proc_lock(target_proc);
target_proc->is_frozen = true;
binder_inner_proc_unlock(target_proc);
if (info.timeout_ms > 0)
ret = wait_event_interruptible_timeout(
target_proc->freeze_wait,
(!target_proc->outstanding_txns),
msecs_to_jiffies(info.timeout_ms));
if (!ret && target_proc->outstanding_txns) {
ret = -EAGAIN;
}
if (ret < 0) {
binder_inner_proc_lock(target_proc);
target_proc->is_frozen = false;
binder_inner_proc_unlock(target_proc);
}
binder_proc_dec_tmpref(target_proc);
if (ret < 0)
goto err;
break;
}
default:
ret = -EINVAL;
goto err;
@ -5193,6 +5279,7 @@ static int binder_open(struct inode *nodp, struct file *filp)
mutex_init(&proc->files_lock);
proc->cred = get_cred(filp->f_cred);
INIT_LIST_HEAD(&proc->todo);
init_waitqueue_head(&proc->freeze_wait);
if (binder_supported_policy(current->policy)) {
proc->default_priority.sched_policy = current->policy;
proc->default_priority.prio = current->normal_prio;
@ -5414,6 +5501,7 @@ static void binder_deferred_release(struct binder_proc *proc)
proc->tmp_ref++;
proc->is_dead = true;
proc->is_frozen = false;
threads = 0;
active_transactions = 0;
while ((n = rb_first(&proc->threads))) {

13
include/uapi/linux/android/binder.h
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@ -264,6 +264,12 @@ struct binder_node_info_for_ref {
__u32 reserved3;
};
struct binder_freeze_info {
__u32 pid;
__u32 enable;
__u32 timeout_ms;
};
#define BINDER_WRITE_READ _IOWR('b', 1, struct binder_write_read)
#define BINDER_SET_IDLE_TIMEOUT _IOW('b', 3, __s64)
#define BINDER_SET_MAX_THREADS _IOW('b', 5, __u32)
@ -274,6 +280,7 @@ struct binder_node_info_for_ref {
#define BINDER_GET_NODE_DEBUG_INFO _IOWR('b', 11, struct binder_node_debug_info)
#define BINDER_GET_NODE_INFO_FOR_REF _IOWR('b', 12, struct binder_node_info_for_ref)
#define BINDER_SET_CONTEXT_MGR_EXT _IOW('b', 13, struct flat_binder_object)
#define BINDER_FREEZE _IOW('b', 14, struct binder_freeze_info)
/*
* NOTE: Two special error codes you should check for when calling
@ -454,6 +461,12 @@ enum binder_driver_return_protocol {
* The the last transaction (either a bcTRANSACTION or
* a bcATTEMPT_ACQUIRE) failed (e.g. out of memory). No parameters.
*/
BR_FROZEN_REPLY = _IO('r', 18),
/*
* The target of the last transaction (either a bcTRANSACTION or
* a bcATTEMPT_ACQUIRE) is frozen. No parameters.
*/
};
enum binder_driver_command_protocol {

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