[PATCH v2 04/11] firmware: arm_ffa: Fix per-vcpu self notifications handling in workqueue

[Sudeep Holla]

Per-vcpu notification handling already runs from a per-cpu work item on
the target cpu. Routing that path back through smp_call_function_single()
re-enters the call-function IPI path and executes the notification
handler with interrupts disabled. That makes the framework path unsafe,
since it takes a mutex, allocates memory with GFP_KERNEL, and invokes
client callbacks.

Handle per-vcpu self notifications directly from the existing per-cpu
work item instead. This keeps the per-vcpu path in task context and
avoids the extra IPI hop entirely.

Fixes: 3a3e2b83e805 ("firmware: arm_ffa: Avoid queuing work when running on the worker queue")
Signed-off-by: Sudeep Holla <sudeep.holla at kernel.org>
---
 drivers/firmware/arm_ffa/driver.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
index 4e66c7325a4e..2241e851f7ae 100644
--- a/drivers/firmware/arm_ffa/driver.c
+++ b/drivers/firmware/arm_ffa/driver.c
@@ -1543,7 +1543,7 @@ static void notif_pcpu_irq_work_fn(struct work_struct *work)
 						 notif_pcpu_work);
 	struct ffa_drv_info *info = pcpu->info;
 
-	ffa_self_notif_handle(smp_processor_id(), true, info);
+	notif_get_and_handle(info);
 }
 
 static const struct ffa_info_ops ffa_drv_info_ops = {

-- 
2.43.0