The patches to support binder's frozen notification feature break the
KMI. This change fixes such issues by (1) moving proc->delivered_freeze
into the existing proc_wrapper struction, (2) dropping the frozen stats
support and (3) amending the STG due to a harmless enum binder_work_type
addition.
These are the reported KMI issues fixed by this patch:
function symbol 'int __traceiter_binder_transaction_received(void*, struct binder_transaction*)' changed
CRC changed from 0x74e9c98b to 0xfe0f8640
type 'struct binder_proc' changed
byte size changed from 584 to 632
member 'struct list_head delivered_death' changed
offset changed by 256
member 'struct list_head delivered_freeze' was added
13 members ('u32 max_threads' .. 'u64 android_oem_data1') changed
offset changed by 384
type 'struct binder_thread' changed
byte size changed from 464 to 496
2 members ('atomic_t tmp_ref' .. 'bool is_dead') changed
offset changed by 224
4 members ('struct task_struct* task' .. 'enum binder_prio_state prio_state') changed
offset changed by 256
type 'struct binder_stats' changed
byte size changed from 216 to 244
member changed from 'atomic_t br[21]' to 'atomic_t br[23]'
type changed from 'atomic_t[21]' to 'atomic_t[23]'
number of elements changed from 21 to 23
member changed from 'atomic_t bc[19]' to 'atomic_t bc[22]'
offset changed from 672 to 736
type changed from 'atomic_t[19]' to 'atomic_t[22]'
number of elements changed from 19 to 22
member changed from 'atomic_t obj_created[7]' to 'atomic_t obj_created[8]'
offset changed from 1280 to 1440
type changed from 'atomic_t[7]' to 'atomic_t[8]'
number of elements changed from 7 to 8
member changed from 'atomic_t obj_deleted[7]' to 'atomic_t obj_deleted[8]'
offset changed from 1504 to 1696
type changed from 'atomic_t[7]' to 'atomic_t[8]'
number of elements changed from 7 to 8
type 'enum binder_work_type' changed
enumerator 'BINDER_WORK_FROZEN_BINDER' (10) was added
enumerator 'BINDER_WORK_CLEAR_FREEZE_NOTIFICATION' (11) was added
Bug: 363013421
Change-Id: If9f1f14a2eda215a4c9cb0823c50c8e0e8079ef1
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Frozen processes present a significant challenge in binder transactions.
When a process is frozen, it cannot, by design, accept and/or respond to
binder transactions. As a result, the sender needs to adjust its
behavior, such as postponing transactions until the peer process
unfreezes. However, there is currently no way to subscribe to these
state change events, making it impossible to implement frozen-aware
behaviors efficiently.
Introduce a binder API for subscribing to frozen state change events.
This allows programs to react to changes in peer process state,
mitigating issues related to binder transactions sent to frozen
processes.
Implementation details:
For a given binder_ref, the state of frozen notification can be one of
the followings:
1. Userspace doesn't want a notification. binder_ref->freeze is null.
2. Userspace wants a notification but none is in flight.
list_empty(&binder_ref->freeze->work.entry) = true
3. A notification is in flight and waiting to be read by userspace.
binder_ref_freeze.sent is false.
4. A notification was read by userspace and kernel is waiting for an ack.
binder_ref_freeze.sent is true.
When a notification is in flight, new state change events are coalesced into
the existing binder_ref_freeze struct. If userspace hasn't picked up the
notification yet, the driver simply rewrites the state. Otherwise, the
notification is flagged as requiring a resend, which will be performed
once userspace acks the original notification that's inflight.
See https://r.android.com/3070045 for how userspace is going to use this
feature.
Signed-off-by: Yu-Ting Tseng <yutingtseng@google.com>
Acked-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20240709070047.4055369-4-yutingtseng@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Bug: 363013421
(cherry picked from commit d579b04a52a183db47dfcb7a44304d7747d551e1
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
char-misc-next)
Change-Id: I5dd32abba932ca7d03ae58660143e075ed778b81
[cmllamas: fix merge conflicts due to missing 0567461a7a6e]
Signed-off-by: Carlos Llamas <cmllamas@google.com>
