Re: [PATCH] optee: ffa: fix sleep in atomic context

On Mon, Jun 02, 2025 at 02:04:35PM +0200, Jens Wiklander wrote:

The OP-TEE driver registers the function notif_callback() for FF-A notifications. However, this function is called in an atomic context leading to errors like this when processing asynchronous notifications:

| BUG: sleeping function called from invalid context at kernel/locking/mutex.c:258 | in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 9, name: kworker/0:0 | preempt_count: 1, expected: 0 | RCU nest depth: 0, expected: 0 | CPU: 0 UID: 0 PID: 9 Comm: kworker/0:0 Not tainted 6.14.0-00019-g657536ebe0aa #13 | Hardware name: linux,dummy-virt (DT) | Workqueue: ffa_pcpu_irq_notification notif_pcpu_irq_work_fn | Call trace: | show_stack+0x18/0x24 (C) | dump_stack_lvl+0x78/0x90 | dump_stack+0x18/0x24 | __might_resched+0x114/0x170 | __might_sleep+0x48/0x98 | mutex_lock+0x24/0x80 | optee_get_msg_arg+0x7c/0x21c | simple_call_with_arg+0x50/0xc0 | optee_do_bottom_half+0x14/0x20 | notif_callback+0x3c/0x48 | handle_notif_callbacks+0x9c/0xe0 | notif_get_and_handle+0x40/0x88 | generic_exec_single+0x80/0xc0 | smp_call_function_single+0xfc/0x1a0 | notif_pcpu_irq_work_fn+0x2c/0x38 | process_one_work+0x14c/0x2b4 | worker_thread+0x2e4/0x3e0 | kthread+0x13c/0x210 | ret_from_fork+0x10/0x20

Fix this by adding work queue to process the notification in a non-atomic context.

Fixes: d0476a59de06 ("optee: ffa_abi: add asynchronous notifications") Signed-off-by: Jens Wiklander jens.wiklander@linaro.org

---

drivers/tee/optee/ffa_abi.c | 41 ++++++++++++++++++++++++------- drivers/tee/optee/optee_private.h | 2 ++ 2 files changed, 34 insertions(+), 9 deletions(-)

Sounds reasonable fix to me, FWIW:

Reviewed-by: Sumit Garg sumit.garg@oss.qualcomm.com

-Sumit

diff --git a/drivers/tee/optee/ffa_abi.c b/drivers/tee/optee/ffa_abi.c index f3af5666bb11..f9ef7d94cebd 100644 --- a/drivers/tee/optee/ffa_abi.c +++ b/drivers/tee/optee/ffa_abi.c @@ -728,12 +728,21 @@ static bool optee_ffa_exchange_caps(struct ffa_device *ffa_dev, return true; } +static void notif_work_fn(struct work_struct *work) +{

• struct optee_ffa *optee_ffa = container_of(work, struct optee_ffa,

• 				   notif_work);
  

• struct optee *optee = container_of(optee_ffa, struct optee, ffa);
• optee_do_bottom_half(optee->ctx);

+}

static void notif_callback(int notify_id, void *cb_data) { struct optee *optee = cb_data; if (notify_id == optee->ffa.bottom_half_value)

• optee_do_bottom_half(optee->ctx);
  

• queue_work(optee->ffa.notif_wq, &optee->ffa.notif_work);
  

  else optee_notif_send(optee, notify_id);

} @@ -817,9 +826,11 @@ static void optee_ffa_remove(struct ffa_device *ffa_dev) struct optee *optee = ffa_dev_get_drvdata(ffa_dev); u32 bottom_half_id = optee->ffa.bottom_half_value;

• if (bottom_half_id != U32_MAX)

• if (bottom_half_id != U32_MAX) { ffa_dev->ops->notifier_ops->notify_relinquish(ffa_dev, bottom_half_id);

• destroy_workqueue(optee->ffa.notif_wq);
  

• } optee_remove_common(optee);

mutex_destroy(&optee->ffa.mutex); @@ -835,6 +846,13 @@ static int optee_ffa_async_notif_init(struct ffa_device *ffa_dev, u32 notif_id = 0; int rc;

• INIT_WORK(&optee->ffa.notif_work, notif_work_fn);
• optee->ffa.notif_wq = create_workqueue("optee_notification");
• if (!optee->ffa.notif_wq) {

• rc = -EINVAL;
  

• goto err;
  

• }
• while (true) { rc = ffa_dev->ops->notifier_ops->notify_request(ffa_dev, is_per_vcpu,

@@ -851,19 +869,24 @@ static int optee_ffa_async_notif_init(struct ffa_device *ffa_dev, * notifications in that case. */ if (rc != -EACCES)

• 	return rc;
  

• 	goto err_wq;
  

  notif_id++; if (notif_id >= OPTEE_FFA_MAX_ASYNC_NOTIF_VALUE)

• 	return rc;
  

• 	goto err_wq;
  

  } optee->ffa.bottom_half_value = notif_id;

rc = enable_async_notif(optee);

• if (rc < 0) {

• ffa_dev->ops->notifier_ops->notify_relinquish(ffa_dev,
  

• 					      notif_id);
  

• optee->ffa.bottom_half_value = U32_MAX;
  

• }

• if (rc < 0)

• goto err_rel;
  

• return 0;

+err_rel:

• ffa_dev->ops->notifier_ops->notify_relinquish(ffa_dev, notif_id);

+err_wq:

• destroy_workqueue(optee->ffa.notif_wq);

+err:

• optee->ffa.bottom_half_value = U32_MAX;

return rc; } diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h index dc0f355ef72a..9526087f0e68 100644 --- a/drivers/tee/optee/optee_private.h +++ b/drivers/tee/optee/optee_private.h @@ -165,6 +165,8 @@ struct optee_ffa { /* Serializes access to @global_ids */ struct mutex mutex; struct rhashtable global_ids;

• struct workqueue_struct *notif_wq;
• struct work_struct notif_work;

}; struct optee; -- 2.43.0