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Message-ID: <d85e4c86-6dd0-4d5d-730b-91217d38ecaa@loongson.cn>
Date: Thu, 14 Dec 2023 09:44:27 +0800
From: Hongchen Zhang <zhanghongchen@...ngson.cn>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
Bojan Smojver <bojan@...ursive.com>, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org, loongson-kernel@...ts.loongnix.cn,
stable@...r.kernel.org, Weihao Li <liweihao@...ngson.cn>
Subject: Re: [PATCH v3] PM: hibernate: use acquire/release ordering when
compress/decompress image
Hi Rafael,
Thanks for your review.
On 2023/12/13 pm 9:52, Rafael J. Wysocki wrote:
> On Wed, Dec 13, 2023 at 2:11 AM Hongchen Zhang
> <zhanghongchen@...ngson.cn> wrote:
>>
>> When we test S4(suspend to disk) on LoongArch 3A6000 platform, the
>> test case sometimes fails. The dmesg log shows the following error:
>> Invalid LZO compressed length
>> After we dig into the code, we find out that:
>> When compress/decompress the image, the synchronization operation
>> between the control thread and the compress/decompress/crc thread
>> uses 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 get a old cmp_len and write to disk. When cpu resume from S4,
>> wrong cmp_len is loaded.
>>
>> To maintain data consistency between two threads, we should use the
>> acquire/release ordering interface. So we change atomic_read/atomic_set
>> to atomic_read_acquire/atomic_set_release.
>>
>> Fixes: 081a9d043c98 ("PM / Hibernate: Improve performance of LZO/plain hibernation, checksum image")
>> Cc: stable@...r.kernel.org
>> Co-developed-by: Weihao Li <liweihao@...ngson.cn>
>
> I gather that the tag above is the only difference between this
> version of the patch and the previous one.
>
Yes.
> It is always better to list the changes made between consecutive
> versions of a patch.
Sorry for not updating the changelog, I will remember this next time.
>
>> Signed-off-by: Weihao Li <liweihao@...ngson.cn>
>> Signed-off-by: Hongchen Zhang <zhanghongchen@...ngson.cn>
>> ---
>> kernel/power/swap.c | 38 +++++++++++++++++++-------------------
>> 1 file changed, 19 insertions(+), 19 deletions(-)
>>
>> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
>> index a2cb0babb5ec..d44f5937f1e5 100644
>> --- a/kernel/power/swap.c
>> +++ b/kernel/power/swap.c
>> @@ -606,11 +606,11 @@ static int crc32_threadfn(void *data)
>> unsigned i;
>>
>> while (1) {
>> - wait_event(d->go, atomic_read(&d->ready) ||
>> + wait_event(d->go, atomic_read_acquire(&d->ready) ||
>> kthread_should_stop());
>> if (kthread_should_stop()) {
>> d->thr = NULL;
>> - atomic_set(&d->stop, 1);
>> + atomic_set_release(&d->stop, 1);
>> wake_up(&d->done);
>> break;
>> }
>> @@ -619,7 +619,7 @@ static int crc32_threadfn(void *data)
>> for (i = 0; i < d->run_threads; i++)
>> *d->crc32 = crc32_le(*d->crc32,
>> d->unc[i], *d->unc_len[i]);
>> - atomic_set(&d->stop, 1);
>> + atomic_set_release(&d->stop, 1);
>> wake_up(&d->done);
>> }
>> return 0;
>> @@ -649,12 +649,12 @@ static int lzo_compress_threadfn(void *data)
>> struct cmp_data *d = data;
>>
>> while (1) {
>> - wait_event(d->go, atomic_read(&d->ready) ||
>> + wait_event(d->go, atomic_read_acquire(&d->ready) ||
>> kthread_should_stop());
>> if (kthread_should_stop()) {
>> d->thr = NULL;
>> d->ret = -1;
>> - atomic_set(&d->stop, 1);
>> + atomic_set_release(&d->stop, 1);
>> wake_up(&d->done);
>> break;
>> }
>> @@ -663,7 +663,7 @@ static int lzo_compress_threadfn(void *data)
>> d->ret = lzo1x_1_compress(d->unc, d->unc_len,
>> d->cmp + LZO_HEADER, &d->cmp_len,
>> d->wrk);
>> - atomic_set(&d->stop, 1);
>> + atomic_set_release(&d->stop, 1);
>> wake_up(&d->done);
>> }
>> return 0;
>> @@ -798,7 +798,7 @@ static int save_image_lzo(struct swap_map_handle *handle,
>>
>> data[thr].unc_len = off;
>>
>> - atomic_set(&data[thr].ready, 1);
>> + atomic_set_release(&data[thr].ready, 1);
>> wake_up(&data[thr].go);
>> }
>>
>> @@ -806,12 +806,12 @@ static int save_image_lzo(struct swap_map_handle *handle,
>> break;
>>
>> crc->run_threads = thr;
>> - atomic_set(&crc->ready, 1);
>> + atomic_set_release(&crc->ready, 1);
>> wake_up(&crc->go);
>>
>> for (run_threads = thr, thr = 0; thr < run_threads; thr++) {
>> wait_event(data[thr].done,
>> - atomic_read(&data[thr].stop));
>> + atomic_read_acquire(&data[thr].stop));
>> atomic_set(&data[thr].stop, 0);
>>
>> ret = data[thr].ret;
>> @@ -850,7 +850,7 @@ static int save_image_lzo(struct swap_map_handle *handle,
>> }
>> }
>>
>> - wait_event(crc->done, atomic_read(&crc->stop));
>> + wait_event(crc->done, atomic_read_acquire(&crc->stop));
>> atomic_set(&crc->stop, 0);
>> }
>>
>> @@ -1132,12 +1132,12 @@ static int lzo_decompress_threadfn(void *data)
>> struct dec_data *d = data;
>>
>> while (1) {
>> - wait_event(d->go, atomic_read(&d->ready) ||
>> + wait_event(d->go, atomic_read_acquire(&d->ready) ||
>> kthread_should_stop());
>> if (kthread_should_stop()) {
>> d->thr = NULL;
>> d->ret = -1;
>> - atomic_set(&d->stop, 1);
>> + atomic_set_release(&d->stop, 1);
>> wake_up(&d->done);
>> break;
>> }
>> @@ -1150,7 +1150,7 @@ static int lzo_decompress_threadfn(void *data)
>> flush_icache_range((unsigned long)d->unc,
>> (unsigned long)d->unc + d->unc_len);
>>
>> - atomic_set(&d->stop, 1);
>> + atomic_set_release(&d->stop, 1);
>> wake_up(&d->done);
>> }
>> return 0;
>> @@ -1335,7 +1335,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
>> }
>>
>> if (crc->run_threads) {
>> - wait_event(crc->done, atomic_read(&crc->stop));
>> + wait_event(crc->done, atomic_read_acquire(&crc->stop));
>> atomic_set(&crc->stop, 0);
>> crc->run_threads = 0;
>> }
>> @@ -1371,7 +1371,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
>> pg = 0;
>> }
>>
>> - atomic_set(&data[thr].ready, 1);
>> + atomic_set_release(&data[thr].ready, 1);
>> wake_up(&data[thr].go);
>> }
>>
>> @@ -1390,7 +1390,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
>>
>> for (run_threads = thr, thr = 0; thr < run_threads; thr++) {
>> wait_event(data[thr].done,
>> - atomic_read(&data[thr].stop));
>> + atomic_read_acquire(&data[thr].stop));
>> atomic_set(&data[thr].stop, 0);
>>
>> ret = data[thr].ret;
>> @@ -1421,7 +1421,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
>> ret = snapshot_write_next(snapshot);
>> if (ret <= 0) {
>> crc->run_threads = thr + 1;
>> - atomic_set(&crc->ready, 1);
>> + atomic_set_release(&crc->ready, 1);
>> wake_up(&crc->go);
>> goto out_finish;
>> }
>> @@ -1429,13 +1429,13 @@ static int load_image_lzo(struct swap_map_handle *handle,
>> }
>>
>> crc->run_threads = thr;
>> - atomic_set(&crc->ready, 1);
>> + atomic_set_release(&crc->ready, 1);
>> wake_up(&crc->go);
>> }
>>
>> out_finish:
>> if (crc->run_threads) {
>> - wait_event(crc->done, atomic_read(&crc->stop));
>> + wait_event(crc->done, atomic_read_acquire(&crc->stop));
>> atomic_set(&crc->stop, 0);
>> }
>> stop = ktime_get();
>> --
>
> Applied as 6.8 material with some edits in the subject and changelog.
>
> Thanks!
>
--
Best Regards
Hongchen Zhang
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