linux-rdma.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Bart Van Assche <bvanassche@acm.org>,
	Jason Gunthorpe <jgg@mellanox.com>,
	Sasha Levin <sashal@kernel.org>,
	linux-rdma@vger.kernel.org
Subject: [PATCH AUTOSEL 5.3 28/33] RDMA/iwcm: Fix a lock inversion issue
Date: Fri, 25 Oct 2019 09:55:00 -0400	[thread overview]
Message-ID: <20191025135505.24762-28-sashal@kernel.org> (raw)
In-Reply-To: <20191025135505.24762-1-sashal@kernel.org>

From: Bart Van Assche <bvanassche@acm.org>

[ Upstream commit b66f31efbdad95ec274345721d99d1d835e6de01 ]

This patch fixes the lock inversion complaint:

============================================
WARNING: possible recursive locking detected
5.3.0-rc7-dbg+ #1 Not tainted
--------------------------------------------
kworker/u16:6/171 is trying to acquire lock:
00000000035c6e6c (&id_priv->handler_mutex){+.+.}, at: rdma_destroy_id+0x78/0x4a0 [rdma_cm]

but task is already holding lock:
00000000bc7c307d (&id_priv->handler_mutex){+.+.}, at: iw_conn_req_handler+0x151/0x680 [rdma_cm]

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&id_priv->handler_mutex);
  lock(&id_priv->handler_mutex);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

3 locks held by kworker/u16:6/171:
 #0: 00000000e2eaa773 ((wq_completion)iw_cm_wq){+.+.}, at: process_one_work+0x472/0xac0
 #1: 000000001efd357b ((work_completion)(&work->work)#3){+.+.}, at: process_one_work+0x476/0xac0
 #2: 00000000bc7c307d (&id_priv->handler_mutex){+.+.}, at: iw_conn_req_handler+0x151/0x680 [rdma_cm]

stack backtrace:
CPU: 3 PID: 171 Comm: kworker/u16:6 Not tainted 5.3.0-rc7-dbg+ #1
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
Workqueue: iw_cm_wq cm_work_handler [iw_cm]
Call Trace:
 dump_stack+0x8a/0xd6
 __lock_acquire.cold+0xe1/0x24d
 lock_acquire+0x106/0x240
 __mutex_lock+0x12e/0xcb0
 mutex_lock_nested+0x1f/0x30
 rdma_destroy_id+0x78/0x4a0 [rdma_cm]
 iw_conn_req_handler+0x5c9/0x680 [rdma_cm]
 cm_work_handler+0xe62/0x1100 [iw_cm]
 process_one_work+0x56d/0xac0
 worker_thread+0x7a/0x5d0
 kthread+0x1bc/0x210
 ret_from_fork+0x24/0x30

This is not a bug as there are actually two lock classes here.

Link: https://lore.kernel.org/r/20190930231707.48259-3-bvanassche@acm.org
Fixes: de910bd92137 ("RDMA/cma: Simplify locking needed for serialization of callbacks")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/infiniband/core/cma.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index a68d0ccf67a43..2e48b59926c19 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -2396,9 +2396,10 @@ static int iw_conn_req_handler(struct iw_cm_id *cm_id,
 		conn_id->cm_id.iw = NULL;
 		cma_exch(conn_id, RDMA_CM_DESTROYING);
 		mutex_unlock(&conn_id->handler_mutex);
+		mutex_unlock(&listen_id->handler_mutex);
 		cma_deref_id(conn_id);
 		rdma_destroy_id(&conn_id->id);
-		goto out;
+		return ret;
 	}
 
 	mutex_unlock(&conn_id->handler_mutex);
-- 
2.20.1


      parent reply	other threads:[~2019-10-25 14:06 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20191025135505.24762-1-sashal@kernel.org>
2019-10-25 13:54 ` [PATCH AUTOSEL 5.3 19/33] net/rds: Whitelist rdma_cookie and rx_tstamp for usercopy Sasha Levin
2019-10-25 13:54 ` [PATCH AUTOSEL 5.3 27/33] RDMA/siw: Fix serialization issue in write_space() Sasha Levin
2019-10-25 13:55 ` Sasha Levin [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191025135505.24762-28-sashal@kernel.org \
    --to=sashal@kernel.org \
    --cc=bvanassche@acm.org \
    --cc=jgg@mellanox.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-rdma@vger.kernel.org \
    --cc=stable@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).