[PATCH for-next 04/12] io_uring: reschedule retargeting at shutdown of ring

Dylan Yudaken
2022-10-31T13:41:53Z

When the ring shuts down, instead of waiting for the work to release it's
reference, just reschedule it to now and get the reference back that way.

Signed-off-by: Dylan Yudaken <dylany@meta.com>
---
io_uring/io_uring.c | 1 +
io_uring/rsrc.c | 26 +++++++++++++++++++++-----
io_uring/rsrc.h | 1 +
3 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index ea2260359c56..32eb305c4ce7 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2751,6 +2751,7 @@ static __cold void io_ring_exit_work(struct work_struct *work)
}

io_req_caches_free(ctx);
+ io_rsrc_retarget_exiting(ctx);

if (WARN_ON_ONCE(time_after(jiffies, timeout))) {
/* there is little hope left, don't run it too often */
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 8d0d40713a63..40b37899e943 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -248,12 +248,20 @@ static unsigned int io_rsrc_retarget_table(struct io_ring_ctx *ctx,
return refs;
}

-static void io_rsrc_retarget_schedule(struct io_ring_ctx *ctx)
+static void io_rsrc_retarget_schedule(struct io_ring_ctx *ctx, bool delay)
__must_hold(&ctx->uring_lock)
{
- percpu_ref_get(&ctx->refs);
- mod_delayed_work(system_wq, &ctx->rsrc_retarget_work, 60 * HZ);
- ctx->rsrc_retarget_scheduled = true;
+ unsigned long del;
+
+ if (delay)
+ del = 60 * HZ;
+ else
+ del = 0;
+
+ if (likely(!mod_delayed_work(system_wq, &ctx->rsrc_retarget_work, del))) {
+ percpu_ref_get(&ctx->refs);
+ ctx->rsrc_retarget_scheduled = true;
+ }
}

static void io_retarget_rsrc_wq_cb(struct io_wq_work *work, void *data)
@@ -332,6 +340,14 @@ void io_rsrc_retarget_work(struct work_struct *work)
percpu_ref_put(&ctx->refs);
}

+void io_rsrc_retarget_exiting(struct io_ring_ctx *ctx)
+{
+ mutex_lock(&ctx->uring_lock);
+ if (ctx->rsrc_retarget_scheduled)
+ io_rsrc_retarget_schedule(ctx, false);
+ mutex_unlock(&ctx->uring_lock);
+}
+
void io_wait_rsrc_data(struct io_rsrc_data *data)
{
if (data && !atomic_dec_and_test(&data->refs))
@@ -414,7 +430,7 @@ void io_rsrc_node_switch(struct io_ring_ctx *ctx,
percpu_ref_kill(&rsrc_node->refs);
ctx->rsrc_node = NULL;
if (!ctx->rsrc_retarget_scheduled)
- io_rsrc_retarget_schedule(ctx);
+ io_rsrc_retarget_schedule(ctx, true);
}

if (!ctx->rsrc_node) {
diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 2b94df8fd9e8..93c66475796e 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -55,6 +55,7 @@ struct io_mapped_ubuf {

void io_rsrc_put_work(struct work_struct *work);
void io_rsrc_retarget_work(struct work_struct *work);
+void io_rsrc_retarget_exiting(struct io_ring_ctx *ctx);
void io_rsrc_refs_refill(struct io_ring_ctx *ctx);
void io_wait_rsrc_data(struct io_rsrc_data *data);
void io_rsrc_node_destroy(struct io_rsrc_node *ref_node);
--
2.30.2