mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: Jia-Ju Bai <baijiaju1990@gmail.com>
To: tariqt@nvidia.com, davem@davemloft.net, kuba@kernel.org
Cc: netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [BUG] net: mellanox: mlx4: possible deadlock in mlx4_xdp_set() and mlx4_en_reset_config()
Date: Mon, 7 Feb 2022 23:16:14 +0800	[thread overview]
Message-ID: <4a850d04-ed6a-5802-7038-a94ad0d466c5@gmail.com> (raw)

Hello,

My static analysis tool reports a possible deadlock in the mlx4 driver 
in Linux 5.16:

mlx4_xdp_set()
   mutex_lock(&mdev->state_lock); --> Line 2778 (Lock A)
   mlx4_en_try_alloc_resources()
     mlx4_en_alloc_resources()
       mlx4_en_destroy_tx_ring()
         mlx4_qp_free()
           wait_for_completion(&qp->free); --> Line 528 (Wait X)

mlx4_en_reset_config()
   mutex_lock(&mdev->state_lock); --> Line 3522 (Lock A)
   mlx4_en_try_alloc_resources()
     mlx4_en_alloc_resources()
       mlx4_en_destroy_tx_ring()
         mlx4_qp_free()
           complete(&qp->free); --> Line 527 (Wake X)

When mlx4_xdp_set() is executed, "Wait X" is performed by holding "Lock 
A". If mlx4_en_reset_config() is executed at this time, "Wake X" cannot 
be performed to wake up "Wait X" in mlx4_xdp_set(), because "Lock A" has 
been already hold by mlx4_xdp_set(), causing a possible deadlock.

I am not quite sure whether this possible problem is real and how to fix 
it if it is real.
Any feedback would be appreciated, thanks :)


Best wishes,
Jia-Ju Bai

             reply	other threads:[~2022-02-07 15:30 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-07 15:16 Jia-Ju Bai [this message]
2022-02-09 10:21 ` Tariq Toukan
2022-02-09 11:32   ` Jia-Ju Bai

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=4a850d04-ed6a-5802-7038-a94ad0d466c5@gmail.com \
    --to=baijiaju1990@gmail.com \
    --cc=davem@davemloft.net \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-rdma@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=tariqt@nvidia.com \
    /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
all inboxes | Powered by JetHome®