rt_data_queue_pop() holds the data queue spinlock while updating the ring
state, then calls rt_data_queue_len(). The length function tries to acquire
the same non-recursive spinlock again, causing an SMP deadlock when a pop
leaves the queue non-empty.
Add a private _data_queue_len_nolock() helper for callers which already hold
the queue lock. Keep the public rt_data_queue_len() protected by one spinlock
acquisition.
This does not change the public API, ABI, queue state transitions, low-water
mark wakeups, or event callback behavior.
Tested on a four-core Spacemit K1 with cyclic HDMI playback and by building the
SMP QEMU Virt64 RISC-V BSP with generic audio, Intel HDA and VirtIO Sound.
Signed-off-by: GuEe-GUI <2991707448@qq.com>
* Synchronize the code of the rt mart branch to the master branch.
* TTY device
* Add lwP code from rt-smart
* Add vnode in DFS, but DFS will be re-write for rt-smart
* There are three libcpu for rt-smart:
* arm/cortex-a, arm/aarch64
* riscv64
Co-authored-by: Rbb666 <zhangbingru@rt-thread.com>
Co-authored-by: zhkag <zhkag@foxmail.com>
GuEe-GUI