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authorJens Axboe <axboe@kernel.dk>2021-02-16 07:17:00 -0700
committerJens Axboe <axboe@kernel.dk>2021-02-21 17:25:22 -0700
commit7c25c0d16ef3c37e49c593ac92f69fa3884d4bb9 (patch)
tree2fe3fa25ca066312bf514c8e34fba0575db99af7
parent27131549060ee87f1c50c56539b8f6c4c1a4acec (diff)
io_uring: remove the need for relying on an io-wq fallback worker
We hit this case when the task is exiting, and we need somewhere to do background cleanup of requests. Instead of relying on the io-wq task manager to do this work for us, just stuff it somewhere where we can safely run it ourselves directly. Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/io-wq.c12
-rw-r--r--fs/io-wq.h2
-rw-r--r--fs/io_uring.c37
3 files changed, 34 insertions, 17 deletions
diff --git a/fs/io-wq.c b/fs/io-wq.c
index c36bbcd823ce..800b299f9772 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -16,7 +16,6 @@
#include <linux/kthread.h>
#include <linux/rculist_nulls.h>
#include <linux/fs_struct.h>
-#include <linux/task_work.h>
#include <linux/blk-cgroup.h>
#include <linux/audit.h>
#include <linux/cpu.h>
@@ -775,9 +774,6 @@ static int io_wq_manager(void *data)
complete(&wq->done);
while (!kthread_should_stop()) {
- if (current->task_works)
- task_work_run();
-
for_each_node(node) {
struct io_wqe *wqe = wq->wqes[node];
bool fork_worker[2] = { false, false };
@@ -800,9 +796,6 @@ static int io_wq_manager(void *data)
schedule_timeout(HZ);
}
- if (current->task_works)
- task_work_run();
-
out:
if (refcount_dec_and_test(&wq->refs)) {
complete(&wq->done);
@@ -1160,11 +1153,6 @@ void io_wq_destroy(struct io_wq *wq)
__io_wq_destroy(wq);
}
-struct task_struct *io_wq_get_task(struct io_wq *wq)
-{
- return wq->manager;
-}
-
static bool io_wq_worker_affinity(struct io_worker *worker, void *data)
{
struct task_struct *task = worker->task;
diff --git a/fs/io-wq.h b/fs/io-wq.h
index 096f1021018e..a1610702f222 100644
--- a/fs/io-wq.h
+++ b/fs/io-wq.h
@@ -124,8 +124,6 @@ typedef bool (work_cancel_fn)(struct io_wq_work *, void *);
enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
void *data, bool cancel_all);
-struct task_struct *io_wq_get_task(struct io_wq *wq);
-
#if defined(CONFIG_IO_WQ)
extern void io_wq_worker_sleeping(struct task_struct *);
extern void io_wq_worker_running(struct task_struct *);
diff --git a/fs/io_uring.c b/fs/io_uring.c
index ace7494e7404..e3eb37304e24 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -456,6 +456,9 @@ struct io_ring_ctx {
struct io_restriction restrictions;
+ /* exit task_work */
+ struct callback_head *exit_task_work;
+
/* Keep this last, we don't need it for the fast path */
struct work_struct exit_work;
};
@@ -2328,11 +2331,14 @@ static int io_req_task_work_add(struct io_kiocb *req)
static void io_req_task_work_add_fallback(struct io_kiocb *req,
task_work_func_t cb)
{
- struct task_struct *tsk = io_wq_get_task(req->ctx->io_wq);
+ struct io_ring_ctx *ctx = req->ctx;
+ struct callback_head *head;
init_task_work(&req->task_work, cb);
- task_work_add(tsk, &req->task_work, TWA_NONE);
- wake_up_process(tsk);
+ do {
+ head = READ_ONCE(ctx->exit_task_work);
+ req->task_work.next = head;
+ } while (cmpxchg(&ctx->exit_task_work, head, &req->task_work) != head);
}
static void __io_req_task_cancel(struct io_kiocb *req, int error)
@@ -8835,6 +8841,28 @@ static int io_remove_personalities(int id, void *p, void *data)
return 0;
}
+static void io_run_ctx_fallback(struct io_ring_ctx *ctx)
+{
+ struct callback_head *work, *head, *next;
+
+ do {
+ do {
+ head = NULL;
+ work = READ_ONCE(ctx->exit_task_work);
+ } while (cmpxchg(&ctx->exit_task_work, work, head) != work);
+
+ if (!work)
+ break;
+
+ do {
+ next = work->next;
+ work->func(work);
+ work = next;
+ cond_resched();
+ } while (work);
+ } while (1);
+}
+
static void io_ring_exit_work(struct work_struct *work)
{
struct io_ring_ctx *ctx = container_of(work, struct io_ring_ctx,
@@ -8848,6 +8876,7 @@ static void io_ring_exit_work(struct work_struct *work)
*/
do {
io_uring_try_cancel_requests(ctx, NULL, NULL);
+ io_run_ctx_fallback(ctx);
} while (!wait_for_completion_timeout(&ctx->ref_comp, HZ/20));
io_ring_ctx_free(ctx);
}
@@ -9243,6 +9272,8 @@ static int io_uring_flush(struct file *file, void *data)
io_req_caches_free(ctx, current);
}
+ io_run_ctx_fallback(ctx);
+
if (!tctx)
return 0;