From: Jason Gunthorpe <jgg@nvidia.com>
Date: Tue, 18 Aug 2020 15:05:26 +0300
Subject: RDMA/ucma: Remove closing and the close_wq
Patch-mainline: v5.10-rc1
Git-commit: 657360d6c74148f8ade5a39430407d64aa157c38
References: bsc#1181147
Use cancel_work_sync() to ensure that the wq is not running and simply
assign NULL to ctx->cm_id to indicate if the work ran or not. Delete the
close_wq since flush_workqueue() is no longer needed.
Link: https://lore.kernel.org/r/20200818120526.702120-15-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
drivers/infiniband/core/ucma.c | 49 ++++++++++++-----------------------------
1 file changed, 15 insertions(+), 34 deletions(-)
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -80,7 +80,6 @@ struct ucma_file {
struct list_head ctx_list;
struct list_head event_list;
wait_queue_head_t poll_wait;
- struct workqueue_struct *close_wq;
};
struct ucma_context {
@@ -96,10 +95,6 @@ struct ucma_context {
u64 uid;
struct list_head list;
- /* mark that device is in process of destroying the internal HW
- * resources, protected by the ctx_table lock
- */
- int closing;
/* sync between removal event and id destroy, protected by file mut */
int destroying;
struct work_struct close_work;
@@ -148,12 +143,9 @@ static struct ucma_context *ucma_get_ctx
xa_lock(&ctx_table);
ctx = _ucma_find_context(id, file);
- if (!IS_ERR(ctx)) {
- if (ctx->closing)
- ctx = ERR_PTR(-EIO);
- else if (!refcount_inc_not_zero(&ctx->ref))
+ if (!IS_ERR(ctx))
+ if (!refcount_inc_not_zero(&ctx->ref))
ctx = ERR_PTR(-ENXIO);
- }
xa_unlock(&ctx_table);
return ctx;
}
@@ -193,6 +185,14 @@ static void ucma_close_id(struct work_st
wait_for_completion(&ctx->comp);
/* No new events will be generated after destroying the id. */
rdma_destroy_id(ctx->cm_id);
+
+ /*
+ * At this point ctx->ref is zero so the only place the ctx can be is in
+ * a uevent or in __destroy_id(). Since the former doesn't touch
+ * ctx->cm_id and the latter sync cancels this, there is no races with
+ * this store.
+ */
+ ctx->cm_id = NULL;
}
static struct ucma_context *ucma_alloc_ctx(struct ucma_file *file)
@@ -356,12 +356,8 @@ static int ucma_event_handler(struct rdm
wake_up_interruptible(&ctx->file->poll_wait);
}
- if (event->event == RDMA_CM_EVENT_DEVICE_REMOVAL && !ctx->destroying) {
- xa_lock(&ctx_table);
- ctx->closing = 1;
- xa_unlock(&ctx_table);
- queue_work(ctx->file->close_wq, &ctx->close_work);
- }
+ if (event->event == RDMA_CM_EVENT_DEVICE_REMOVAL && !ctx->destroying)
+ queue_work(system_unbound_wq, &ctx->close_work);
return 0;
}
@@ -577,17 +573,10 @@ static int __destroy_id(struct ucma_cont
ucma_put_ctx(ctx);
}
- flush_workqueue(ctx->file->close_wq);
+ cancel_work_sync(&ctx->close_work);
/* At this point it's guaranteed that there is no inflight closing task */
- xa_lock(&ctx_table);
- if (!ctx->closing) {
- xa_unlock(&ctx_table);
- ucma_put_ctx(ctx);
- wait_for_completion(&ctx->comp);
- rdma_destroy_id(ctx->cm_id);
- } else {
- xa_unlock(&ctx_table);
- }
+ if (ctx->cm_id)
+ ucma_close_id(&ctx->close_work);
return ucma_free_ctx(ctx);
}
@@ -1788,13 +1777,6 @@ static int ucma_open(struct inode *inode
if (!file)
return -ENOMEM;
- file->close_wq = alloc_ordered_workqueue("ucma_close_id",
- WQ_MEM_RECLAIM);
- if (!file->close_wq) {
- kfree(file);
- return -ENOMEM;
- }
-
INIT_LIST_HEAD(&file->event_list);
INIT_LIST_HEAD(&file->ctx_list);
init_waitqueue_head(&file->poll_wait);
@@ -1825,7 +1807,6 @@ static int ucma_close(struct inode *inod
xa_erase(&ctx_table, ctx->id);
__destroy_id(ctx);
}
- destroy_workqueue(file->close_wq);
kfree(file);
return 0;
}