[for-next,V7,6/6] IB/ucma: HW Device hot-removal support

Message ID	1438697008-26209-7-git-send-email-yishaih@mellanox.com (mailing list archive)
State	Superseded
Headers	show Return-Path: <linux-rdma-owner@kernel.org> From: Yishai Hadas <yishaih@mellanox.com> To: dledford@redhat.com Cc: linux-rdma@vger.kernel.org, yishaih@mellanox.com, raindel@mellanox.com, jackm@mellanox.com, jgunthorpe@obsidianresearch.com Subject: [PATCH for-next V7 6/6] IB/ucma: HW Device hot-removal support Date: Tue, 4 Aug 2015 17:03:28 +0300 Message-Id: <1438697008-26209-7-git-send-email-yishaih@mellanox.com> In-Reply-To: <1438697008-26209-1-git-send-email-yishaih@mellanox.com> References: <1438697008-26209-1-git-send-email-yishaih@mellanox.com> Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk

diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c index 29b2121..e9037df 100644 --- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -74,6 +74,7 @@ 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 { @@ -89,6 +90,9 @@ struct ucma_context { struct list_head list; struct list_head mc_list; + int closing; + int destroying; + struct work_struct close_work; }; struct ucma_multicast { @@ -107,6 +111,7 @@ struct ucma_event { struct list_head list; struct rdma_cm_id *cm_id; struct rdma_ucm_event_resp resp; + struct work_struct close_work; }; static DEFINE_MUTEX(mut); @@ -132,8 +137,12 @@ static struct ucma_context *ucma_get_ctx(struct ucma_file *file, int id) mutex_lock(&mut); ctx = _ucma_find_context(id, file); - if (!IS_ERR(ctx)) - atomic_inc(&ctx->ref); + if (!IS_ERR(ctx)) { + if (ctx->closing) + ctx = ERR_PTR(-EIO); + else + atomic_inc(&ctx->ref); + } mutex_unlock(&mut); return ctx; } @@ -144,6 +153,34 @@ static void ucma_put_ctx(struct ucma_context *ctx) complete(&ctx->comp); } +static void ucma_close_event_id(struct work_struct *work) +{ + struct ucma_event *uevent_close = container_of(work, struct ucma_event, close_work); + + rdma_destroy_id(uevent_close->cm_id); + kfree(uevent_close); +} + +static void ucma_close_id(struct work_struct *work) +{ + struct ucma_context *ctx = container_of(work, struct ucma_context, close_work); + + /* Fence to ensure that ctx->closing was seen by all + * ucma_get_ctx running + */ + mutex_lock(&mut); + mutex_unlock(&mut); + + /* once all inflight tasks are finished, we close all underlying + * resources. The context is still alive till its explicit destryoing + * by its creator. + */ + ucma_put_ctx(ctx); + wait_for_completion(&ctx->comp); + /* No new events will be generated after destroying the id. */ + rdma_destroy_id(ctx->cm_id); +} + static struct ucma_context *ucma_alloc_ctx(struct ucma_file *file) { struct ucma_context *ctx; @@ -152,6 +189,7 @@ static struct ucma_context *ucma_alloc_ctx(struct ucma_file *file) if (!ctx) return NULL; + INIT_WORK(&ctx->close_work, ucma_close_id); atomic_set(&ctx->ref, 1); init_completion(&ctx->comp); INIT_LIST_HEAD(&ctx->mc_list); @@ -242,6 +280,42 @@ static void ucma_set_event_context(struct ucma_context *ctx, } } +/* Called with file->mut locked for the relevant context. */ +static void ucma_removal_event_handler(struct rdma_cm_id *cm_id) +{ + struct ucma_context *ctx = cm_id->context; + struct ucma_event *con_req_eve; + int event_found = 0; + + if (ctx->destroying) + return; + + /* only if context is pointing to cm_id that it owns it and can be + * queued to be closed, otherwise that cm_id is an inflight one that + * is part of that context event list pending to be detached and + * reattached to its new context as part of ucma_get_event, + * handled separately below. + */ + if (ctx->cm_id == cm_id) { + ctx->closing = 1; + queue_work(ctx->file->close_wq, &ctx->close_work); + return; + } + + list_for_each_entry(con_req_eve, &ctx->file->event_list, list) { + if (con_req_eve->cm_id == cm_id && + con_req_eve->resp.event == RDMA_CM_EVENT_CONNECT_REQUEST) { + list_del(&con_req_eve->list); + INIT_WORK(&con_req_eve->close_work, ucma_close_event_id); + queue_work(ctx->file->close_wq, &con_req_eve->close_work); + event_found = 1; + break; + } + } + if (!event_found) + printk(KERN_ERR "ucma_removal_event_handler: warning: connect request event wasn't found\n"); +} + static int ucma_event_handler(struct rdma_cm_id *cm_id, struct rdma_cm_event *event) { @@ -276,14 +350,21 @@ static int ucma_event_handler(struct rdma_cm_id *cm_id, * We ignore events for new connections until userspace has set * their context. This can only happen if an error occurs on a * new connection before the user accepts it. This is okay, - * since the accept will just fail later. + * since the accept will just fail later. However, we do need + * to release the underlying HW resources in case of a device + * removal event. */ + if (event->event == RDMA_CM_EVENT_DEVICE_REMOVAL) + ucma_removal_event_handler(cm_id); + kfree(uevent); goto out; } list_add_tail(&uevent->list, &ctx->file->event_list); wake_up_interruptible(&ctx->file->poll_wait); + if (event->event == RDMA_CM_EVENT_DEVICE_REMOVAL) + ucma_removal_event_handler(cm_id); out: mutex_unlock(&ctx->file->mut); return ret; @@ -442,9 +523,15 @@ static void ucma_cleanup_mc_events(struct ucma_multicast *mc) } /* - * We cannot hold file->mut when calling rdma_destroy_id() or we can - * deadlock. We also acquire file->mut in ucma_event_handler(), and - * rdma_destroy_id() will wait until all callbacks have completed. + * ucma_free_ctx is called after the underlying rdma CM-ID is destroyed. At + * this point, no new events will be reported from the hardware. However, we + * still need to cleanup the UCMA context for this ID. Specifically, there + * might be events that have not yet been consumed by the user space software. + * These might include pending connect requests which we have not completed + * processing. We cannot call rdma_destroy_id while holding the lock of the + * context (file->mut), as it might cause a deadlock. We therefore extract all + * relevant events from the context pending events list while holding the + * mutex. After that we release them as needed. */ static int ucma_free_ctx(struct ucma_context *ctx) { @@ -452,8 +539,6 @@ static int ucma_free_ctx(struct ucma_context *ctx) struct ucma_event *uevent, *tmp; LIST_HEAD(list); - /* No new events will be generated after destroying the id. */ - rdma_destroy_id(ctx->cm_id); ucma_cleanup_multicast(ctx); @@ -501,10 +586,20 @@ static ssize_t ucma_destroy_id(struct ucma_file *file, const char __user *inbuf, if (IS_ERR(ctx)) return PTR_ERR(ctx); - ucma_put_ctx(ctx); - wait_for_completion(&ctx->comp); - resp.events_reported = ucma_free_ctx(ctx); + mutex_lock(&ctx->file->mut); + ctx->destroying = 1; + mutex_unlock(&ctx->file->mut); + + flush_workqueue(ctx->file->close_wq); + /* At this point it's guaranteed that there is no inflight + * closing task */ + if (!ctx->closing) { + ucma_put_ctx(ctx); + wait_for_completion(&ctx->comp); + rdma_destroy_id(ctx->cm_id); + } + resp.events_reported = ucma_free_ctx(ctx); if (copy_to_user((void __user *)(unsigned long)cmd.response, &resp, sizeof(resp))) ret = -EFAULT; @@ -1529,6 +1624,7 @@ static int ucma_open(struct inode *inode, struct file *filp) INIT_LIST_HEAD(&file->ctx_list); init_waitqueue_head(&file->poll_wait); mutex_init(&file->mut); + file->close_wq = create_singlethread_workqueue("ucma_close_id"); filp->private_data = file; file->filp = filp; @@ -1543,16 +1639,28 @@ static int ucma_close(struct inode *inode, struct file *filp) mutex_lock(&file->mut); list_for_each_entry_safe(ctx, tmp, &file->ctx_list, list) { + ctx->destroying = 1; mutex_unlock(&file->mut); mutex_lock(&mut); idr_remove(&ctx_idr, ctx->id); mutex_unlock(&mut); + flush_workqueue(file->close_wq); + /* At that step once ctx was marked as destroying and workqueue + * was flushed we are safe from any inflights handlers that + * might put other closing task. + */ + if (!ctx->closing) + /* rdma_destroy_id ensures that no event handlers are + * inflight for that id before releasing it. + */ + rdma_destroy_id(ctx->cm_id); ucma_free_ctx(ctx); mutex_lock(&file->mut); } mutex_unlock(&file->mut); + destroy_workqueue(file->close_wq); kfree(file); return 0; }

[for-next,V7,6/6] IB/ucma: HW Device hot-removal support

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