From 657360d6c74148f8ade5a39430407d64aa157c38 Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Tue, 18 Aug 2020 15:05:26 +0300 Subject: RDMA/ucma: Remove closing and the close_wq 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 Signed-off-by: Jason Gunthorpe --- drivers/infiniband/core/ucma.c | 49 +++++++++++++----------------------------- 1 file changed, 15 insertions(+), 34 deletions(-) (limited to 'drivers/infiniband/core') diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c index 40539c9625d6..46d37e470e98 100644 --- 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(struct ucma_file *file, int id) 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_struct *work) 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 rdma_cm_id *cm_id, 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_context *ctx) 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, struct file *filp) 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 *inode, struct file *filp) xa_erase(&ctx_table, ctx->id); __destroy_id(ctx); } - destroy_workqueue(file->close_wq); kfree(file); return 0; } -- cgit v1.2.3-59-g8ed1b