erofs: wake up all waiters after z_erofs_lzma_head ready

In the Linux kernel, the following vulnerability has been resolved:

erofs: wake up all waiters after z_erofs_lzma_head ready

When the user mounts the erofs second times, the decompression thread

may hung. The problem happens due to a sequence of steps like the

following:

1) Task A called z_erofs_load_lzma_config which obtain all of the node

from the z_erofs_lzma_head.

2) At this time, task B called the z_erofs_lzma_decompress and wanted to

get a node. But the z_erofs_lzma_head was empty, the Task B had to

sleep.

3) Task A release nodes and push nodes into the z_erofs_lzma_head. But

task B was still sleeping.

One example report when the hung happens:

task:kworker/u3:1 state:D stack:14384 pid: 86 ppid: 2 flags:0x00004000

Workqueue: erofs_unzipd z_erofs_decompressqueue_work

Call Trace:

<TASK>

__schedule+0x281/0x760

schedule+0x49/0xb0

z_erofs_lzma_decompress+0x4bc/0x580

? cpu_core_flags+0x10/0x10

z_erofs_decompress_pcluster+0x49b/0xba0

? __update_load_avg_se+0x2b0/0x330

? __update_load_avg_se+0x2b0/0x330

? update_load_avg+0x5f/0x690

? update_load_avg+0x5f/0x690

? set_next_entity+0xbd/0x110

? _raw_spin_unlock+0xd/0x20

z_erofs_decompress_queue.isra.0+0x2e/0x50

z_erofs_decompressqueue_work+0x30/0x60

process_one_work+0x1d3/0x3a0

worker_thread+0x45/0x3a0

? process_one_work+0x3a0/0x3a0

kthread+0xe2/0x110

? kthread_complete_and_exit+0x20/0x20

ret_from_fork+0x22/0x30

</TASK>