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authorHao Xu <haoxu@linux.alibaba.com>2021-08-08 15:54:34 +0200
committerJens Axboe <axboe@kernel.dk>2021-08-10 03:59:06 +0200
commit47cae0c71f7a126903f930191e6e9f103674aca1 (patch)
treeca1d73da05e7f9699b156f4b4b0f40bccdefb5d9 /fs/io-wq.c
parentio-wq: fix bug of creating io-wokers unconditionally (diff)
downloadlinux-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.c18
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);