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From: Leon Romanovsky <leon@kernel.org>
To: Doug Ledford <dledford@redhat.com>, Jason Gunthorpe <jgg@nvidia.com>
Cc: Leon Romanovsky <leonro@mellanox.com>, linux-rdma@vger.kernel.org
Subject: [PATCH rdma-next 11/14] RDMA/ucma: Change backlog into an atomic
Date: Tue, 18 Aug 2020 15:05:23 +0300
Message-ID: <20200818120526.702120-12-leon@kernel.org> (raw)
In-Reply-To: <20200818120526.702120-1-leon@kernel.org>

From: Jason Gunthorpe <jgg@nvidia.com>

There is no reason to grab the file->mut just to do this inc/dec work. Use
an atomic.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
---
 drivers/infiniband/core/ucma.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index ad78b05de656..8be8ff14ab62 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -88,7 +88,7 @@ struct ucma_context {
 	struct completion	comp;
 	refcount_t		ref;
 	int			events_reported;
-	int			backlog;
+	atomic_t		backlog;
 
 	struct ucma_file	*file;
 	struct rdma_cm_id	*cm_id;
@@ -348,12 +348,11 @@ static int ucma_event_handler(struct rdma_cm_id *cm_id,
 	uevent->resp.ece.attr_mod = event->ece.attr_mod;
 
 	if (event->event == RDMA_CM_EVENT_CONNECT_REQUEST) {
-		if (!ctx->backlog) {
+		if (!atomic_add_unless(&ctx->backlog, -1, 0)) {
 			ret = -ENOMEM;
 			kfree(uevent);
 			goto out;
 		}
-		ctx->backlog--;
 	} else if (!ctx->uid || ctx->cm_id != cm_id) {
 		/*
 		 * We ignore events for new connections until userspace has set
@@ -432,7 +431,7 @@ static ssize_t ucma_get_event(struct ucma_file *file, const char __user *inbuf,
 	}
 
 	if (ctx) {
-		uevent->ctx->backlog++;
+		atomic_inc(&uevent->ctx->backlog);
 		uevent->cm_id->context = ctx;
 		ucma_finish_ctx(ctx);
 	}
@@ -1136,10 +1135,12 @@ static ssize_t ucma_listen(struct ucma_file *file, const char __user *inbuf,
 	if (IS_ERR(ctx))
 		return PTR_ERR(ctx);
 
-	ctx->backlog = cmd.backlog > 0 && cmd.backlog < max_backlog ?
-		       cmd.backlog : max_backlog;
+	if (cmd.backlog <= 0 || cmd.backlog > max_backlog)
+		cmd.backlog = max_backlog;
+	atomic_set(&ctx->backlog, cmd.backlog);
+
 	mutex_lock(&ctx->mutex);
-	ret = rdma_listen(ctx->cm_id, ctx->backlog);
+	ret = rdma_listen(ctx->cm_id, cmd.backlog);
 	mutex_unlock(&ctx->mutex);
 	ucma_put_ctx(ctx);
 	return ret;
-- 
2.26.2


  parent reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-18 12:05 [PATCH rdma-next 00/14] Cleanup locking and events in ucma Leon Romanovsky
2020-08-18 12:05 ` [PATCH rdma-next 01/14] RDMA/ucma: Fix refcount 0 incr in ucma_get_ctx() Leon Romanovsky
2020-08-18 12:05 ` [PATCH rdma-next 02/14] RDMA/ucma: Remove unnecessary locking of file->ctx_list in close Leon Romanovsky
2020-08-18 12:05 ` [PATCH rdma-next 03/14] RDMA/ucma: Consolidate the two destroy flows Leon Romanovsky
2020-08-18 12:05 ` [PATCH rdma-next 04/14] RDMA/ucma: Fix error cases around ucma_alloc_ctx() Leon Romanovsky
2020-08-18 12:05 ` [PATCH rdma-next 05/14] RDMA/ucma: Remove mc_list and rely on xarray Leon Romanovsky
2020-08-18 12:05 ` [PATCH rdma-next 06/14] RDMA/cma: Add missing locking to rdma_accept() Leon Romanovsky
2021-02-09 14:46   ` Chuck Lever
2021-02-09 15:40     ` Jason Gunthorpe
2020-08-18 12:05 ` [PATCH rdma-next 07/14] RDMA/ucma: Do not use file->mut to lock destroying Leon Romanovsky
2020-08-18 12:05 ` [PATCH rdma-next 08/14] RDMA/ucma: Fix the locking of ctx->file Leon Romanovsky
2020-08-18 12:05 ` [PATCH rdma-next 09/14] RDMA/ucma: Fix locking for ctx->events_reported Leon Romanovsky
2020-08-18 12:05 ` [PATCH rdma-next 10/14] RDMA/ucma: Add missing locking around rdma_leave_multicast() Leon Romanovsky
2020-08-18 12:05 ` Leon Romanovsky [this message]
2020-08-18 12:05 ` [PATCH rdma-next 12/14] RDMA/ucma: Narrow file->mut in ucma_event_handler() Leon Romanovsky
2020-08-18 12:05 ` [PATCH rdma-next 13/14] RDMA/ucma: Rework how new connections are passed through event delivery Leon Romanovsky
2020-08-18 12:05 ` [PATCH rdma-next 14/14] RDMA/ucma: Remove closing and the close_wq Leon Romanovsky
2020-08-27 11:39 ` [PATCH rdma-next 00/14] Cleanup locking and events in ucma Jason Gunthorpe

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