Hi all,

This series contains a couple of APR enhancements and a rework of the RX
processing path.

The first two patches makes code more robust for trival issues in the APR core.

Remove stale service entries from the IDR when apr_add_device()
fails before the device is registered.
Validate incoming packet lengths using the header size appropriate
for the active packet router type (APR or GPR).

The final patch moves RX buffering and work items from the packet
router to individual services.

Today all incoming packets are serialized through a single work item and
a global RX queue. If one service callback blocks or takes a long time
to complete, packet processing for all other services is delayed. This
can lead to command timeouts when responses are stuck behind unrelated
work.

With this change, packets are queued and processed on a per-service
basis, preserving message ordering within each service while allowing
unrelated services to make progress independently. Since queued packets
may outlive service removal, a reference count is added to keep the
service object alive until all queued packets have been processed.

The shared APR workqueue is also converted to an unbound reclaim
workqueue so multiple services can process packets in parallel.

Thanks,
Srini

Srinivas Kandagatla (3):
  soc: qcom: apr: Remove service from IDR before registration failure
  soc: qcom: apr: Check response packet length by router type
  soc: qcom: apr: Process RX messages using per-service work items

 drivers/soc/qcom/apr.c       | 283 ++++++++++++++++++++++++-----------
 include/linux/soc/qcom/apr.h |   6 +
 2 files changed, 200 insertions(+), 89 deletions(-)

-- 
2.47.3

Hi,

On 5/14/26 12:50 PM, Srinivas Kandagatla wrote:
> Hi all,
> [..]
> Srinivas Kandagatla (3):
>    soc: qcom: apr: Remove service from IDR before registration failure
>    soc: qcom: apr: Check response packet length by router type
>    soc: qcom: apr: Process RX messages using per-service work items
>
>   drivers/soc/qcom/apr.c       | 283 ++++++++++++++++++++++++-----------
>   include/linux/soc/qcom/apr.h |   6 +
>   2 files changed, 200 insertions(+), 89 deletions(-)

just saw a crash under apr_service_rxwq -> graph_callback with this 
series applied. Can't say it really is to blame, but still replying here 
because it was applied..

hamoa, quad WSA speakers, pipewire, audio playing from 
https://flathub.org/en/apps/com.rafaelmardojai.Blanket, crashed when 
opening pavucontrol (display froze with the pavucontrol UI already loaded)

<1>[577090.453413] Unable to handle kernel NULL pointer dereference at 
virtual address 0000000000000050
[..]
<4>[577090.453924] CPU: 0 UID: 0 PID: 946838 Comm: kworker/u49:1 
Tainted: G        W  7.1.0-rc4-next-20260519-uwu+ #116 PREEMPT(full)
<4>[577090.453933] Tainted: [W]=WARN
<4>[577090.453936] Hardware name: Dell Inc. Latitude 7455/0FK7MX, BIOS 
2.13.0 09/19/2025
<4>[577090.453941] Workqueue: qcom_apr_rx apr_service_rxwq [apr] 
(../drivers/soc/qcom/apr.c:359)
<4>[577090.453957] pstate: 61400009 (nZCv daif +PAN -UAO -TCO +DIT -SSBS 
BTYPE=--)
<4>[577090.453963] pc : graph_callback+0x1a8/0x280 [snd_q6apm] 
(../sound/soc/qcom/qdsp6/q6apm.c:577)
<4>[577090.453977] lr : graph_callback+0x194/0x280 [snd_q6apm] 
(../sound/soc/qcom/qdsp6/q6apm.c:572)
[..]
<4>[577090.454086] Call trace:
<4>[577090.454090]  graph_callback+0x1a8/0x280 [snd_q6apm] 
(../sound/soc/qcom/qdsp6/q6apm.c:577) (P)
<4>[577090.454100]  apr_service_rxwq+0x274/0x3b8 [apr] 
(../drivers/soc/qcom/apr.c:535)
<4>[577090.454109]  process_scheduled_works+0x190/0x500 
(../kernel/workqueue.c:3323)
<4>[577090.454124]  worker_thread+0x230/0x330 (../include/linux/list.h:404)
<4>[577090.454133]  kthread+0x120/0x158 (../kernel/kthread.c:438)
<4>[577090.454141]  ret_from_fork+0x10/0x20 
(../arch/arm64/kernel/entry.S:842)
<0>[577090.454153] Code: f94026e9 910242e0 f9400e95 d37ced08 (f8686936)
<4>[577090.454158] ---[ end trace 0000000000000000 ]---


Line 577 is         atomic_set(&graph->tx_data.hw_ptr, hdr->token + 1);

weird, both graph and hdr have been dereferenced before this line..


Thanks,
~val