PM: hibernate: Enforce ordering during image compression/decompression
authorHongchen Zhang <zhanghongchen@loongson.cn>
Thu, 16 Nov 2023 00:56:09 +0000 (08:56 +0800)
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>
Fri, 15 Dec 2023 11:34:12 +0000 (12:34 +0100)
commit71cd7e80cfde548959952eac7063aeaea1f2e1c6
tree373c6b270c9e2d58f9d3913e01cd2c492c67366a
parent0c4cae1bc00d31c78858c184ede351baea232bdb
PM: hibernate: Enforce ordering during image compression/decompression

An S4 (suspend to disk) test on the LoongArch 3A6000 platform sometimes
fails with the following error messaged in the dmesg log:

Invalid LZO compressed length

That happens because when compressing/decompressing the image, the
synchronization between the control thread and the compress/decompress/crc
thread is based on a relaxed ordering interface, which is unreliable, and the
following situation may occur:

CPU 0 CPU 1
save_image_lzo lzo_compress_threadfn
  atomic_set(&d->stop, 1);
  atomic_read(&data[thr].stop)
  data[thr].cmp = data[thr].cmp_len;
     WRITE data[thr].cmp_len

Then CPU0 gets a stale cmp_len and writes it to disk. During resume from S4,
wrong cmp_len is loaded.

To maintain data consistency between the two threads, use the acquire/release
variants of atomic set and read operations.

Fixes: 081a9d043c98 ("PM / Hibernate: Improve performance of LZO/plain hibernation, checksum image")
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Hongchen Zhang <zhanghongchen@loongson.cn>
Co-developed-by: Weihao Li <liweihao@loongson.cn>
Signed-off-by: Weihao Li <liweihao@loongson.cn>
[ rjw: Subject rewrite and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
kernel/power/swap.c