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bcache: fixup multiple threads crash

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When multiple threads to check btree nodes in parallel, the main
thread wait for all threads to stop or CACHE_SET_IO_DISABLE flag:

wait_event_interruptible(check_state->wait,
                         atomic_read(&check_state->started) == 0 ||
                         test_bit(CACHE_SET_IO_DISABLE, &c->flags));

However, the bch_btree_node_read and bch_btree_node_read_done
maybe call bch_cache_set_error, then the CACHE_SET_IO_DISABLE
will be set. If the flag already set, the main thread return
error. At the same time, maybe some threads still running and
read NULL pointer, the kernel will crash.

This patch change the event wait condition, the main thread must
wait for all threads to stop.

Fixes: 8e7102273f ("bcache: make bch_btree_check() to be multithreaded")
Signed-off-by: Mingzhe Zou <mingzhe.zou@easystack.cn>
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Coly Li <colyli@suse.de>
This commit is contained in:
Mingzhe Zou 2022-02-11 14:39:15 +08:00 committed by Coly Li
parent 7b1002f7cf
commit 887554ab96
2 changed files with 8 additions and 4 deletions
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6
drivers/md/bcache/btree.c
View File

@ -2060,9 +2060,11 @@ int bch_btree_check(struct cache_set *c)
}
}
/*
* Must wait for all threads to stop.
*/
wait_event_interruptible(check_state->wait,
atomic_read(&check_state->started) == 0 ||
test_bit(CACHE_SET_IO_DISABLE, &c->flags));
atomic_read(&check_state->started) == 0);
for (i = 0; i < check_state->total_threads; i++) {
if (check_state->infos[i].result) {

6
drivers/md/bcache/writeback.c
View File

@ -1001,9 +1001,11 @@ void bch_sectors_dirty_init(struct bcache_device *d)
}
}
/*
* Must wait for all threads to stop.
*/
wait_event_interruptible(state->wait,
atomic_read(&state->started) == 0 ||
test_bit(CACHE_SET_IO_DISABLE, &c->flags));
atomic_read(&state->started) == 0);
out:
kfree(state);