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author | Hao Xu <haoxu@linux.alibaba.com> | 2021-08-08 15:54:34 +0200 |
---|---|---|
committer | Jens Axboe <axboe@kernel.dk> | 2021-08-10 03:59:06 +0200 |
commit | 47cae0c71f7a126903f930191e6e9f103674aca1 (patch) | |
tree | ca1d73da05e7f9699b156f4b4b0f40bccdefb5d9 /fs/io-wq.c | |
parent | io-wq: fix bug of creating io-wokers unconditionally (diff) | |
download | linux-47cae0c71f7a126903f930191e6e9f103674aca1.tar.xz linux-47cae0c71f7a126903f930191e6e9f103674aca1.zip |
io-wq: fix IO_WORKER_F_FIXED issue in create_io_worker()
There may be cases like:
A B
spin_lock(wqe->lock)
nr_workers is 0
nr_workers++
spin_unlock(wqe->lock)
spin_lock(wqe->lock)
nr_wokers is 1
nr_workers++
spin_unlock(wqe->lock)
create_io_worker()
acct->worker is 1
create_io_worker()
acct->worker is 1
There should be one worker marked IO_WORKER_F_FIXED, but no one is.
Fix this by introduce a new agrument for create_io_worker() to indicate
if it is the first worker.
Fixes: 3d4e4face9c1 ("io-wq: fix no lock protection of acct->nr_worker")
Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20210808135434.68667-3-haoxu@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io-wq.c')
-rw-r--r-- | fs/io-wq.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/fs/io-wq.c b/fs/io-wq.c index ac8604a35169..7d2ed8c7dd31 100644 --- a/fs/io-wq.c +++ b/fs/io-wq.c @@ -129,7 +129,7 @@ struct io_cb_cancel_data { bool cancel_all; }; -static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index); +static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index, bool first); static void io_wqe_dec_running(struct io_worker *worker); static bool io_worker_get(struct io_worker *worker) @@ -248,18 +248,20 @@ static void io_wqe_wake_worker(struct io_wqe *wqe, struct io_wqe_acct *acct) rcu_read_unlock(); if (!ret) { - bool do_create = false; + bool do_create = false, first = false; raw_spin_lock_irq(&wqe->lock); if (acct->nr_workers < acct->max_workers) { atomic_inc(&acct->nr_running); atomic_inc(&wqe->wq->worker_refs); + if (!acct->nr_workers) + first = true; acct->nr_workers++; do_create = true; } raw_spin_unlock_irq(&wqe->lock); if (do_create) - create_io_worker(wqe->wq, wqe, acct->index); + create_io_worker(wqe->wq, wqe, acct->index, first); } } @@ -282,7 +284,7 @@ static void create_worker_cb(struct callback_head *cb) struct io_wq *wq; struct io_wqe *wqe; struct io_wqe_acct *acct; - bool do_create = false; + bool do_create = false, first = false; cwd = container_of(cb, struct create_worker_data, work); wqe = cwd->wqe; @@ -290,12 +292,14 @@ static void create_worker_cb(struct callback_head *cb) acct = &wqe->acct[cwd->index]; raw_spin_lock_irq(&wqe->lock); if (acct->nr_workers < acct->max_workers) { + if (!acct->nr_workers) + first = true; acct->nr_workers++; do_create = true; } raw_spin_unlock_irq(&wqe->lock); if (do_create) { - create_io_worker(wq, cwd->wqe, cwd->index); + create_io_worker(wq, wqe, cwd->index, first); } else { atomic_dec(&acct->nr_running); io_worker_ref_put(wq); @@ -637,7 +641,7 @@ void io_wq_worker_sleeping(struct task_struct *tsk) raw_spin_unlock_irq(&worker->wqe->lock); } -static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index) +static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index, bool first) { struct io_wqe_acct *acct = &wqe->acct[index]; struct io_worker *worker; @@ -678,7 +682,7 @@ fail: worker->flags |= IO_WORKER_F_FREE; if (index == IO_WQ_ACCT_BOUND) worker->flags |= IO_WORKER_F_BOUND; - if ((acct->nr_workers == 1) && (worker->flags & IO_WORKER_F_BOUND)) + if (first && (worker->flags & IO_WORKER_F_BOUND)) worker->flags |= IO_WORKER_F_FIXED; raw_spin_unlock_irq(&wqe->lock); wake_up_new_task(tsk); |