RE: [PATCH] qed: fix possible unpaired spin_{un}lock_bh in _qed_mcp_cmd_and_union()

-----Original Message-----
From: Jakub Kicinski <kuba@kernel.org>
Sent: Tuesday, July 20, 2021 5:06 PM
To: Justin He <redacted>
Cc: Prabhakar Kushwaha <redacted>; David S. Miller
[off-list ref]; Ariel Elior [off-list ref]; GR-everest-linux-
l2@marvell.com; netdev@vger.kernel.org; Linux Kernel Mailing List <linux-
kernel@vger.kernel.org>; nd [off-list ref]; Shai Malin [off-list ref];
Shai Malin [off-list ref]; Prabhakar Kushwaha [off-list ref]
Subject: Re: [PATCH] qed: fix possible unpaired spin_{un}lock_bh in
_qed_mcp_cmd_and_union()

On Tue, 20 Jul 2021 02:02:26 +0000, Justin He wrote:

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For instance:
_qed_mcp_cmd_and_union()
  In while loop
    spin_lock_bh()
    qed_mcp_has_pending_cmd() (assume false), will break the loop

I agree till here.

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  if (cnt >= max_retries) {
...
    return -EAGAIN; <-- here returns -EAGAIN without invoking bh

unlock

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  }

Because of break, cnt has not been increased.
   - cnt is still less than max_retries.
  - if (cnt >= max_retries) will not be *true*, leading to

spin_unlock_bh().

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Hence pairing completed.

Sorry, indeed. Let me check other possibilities.
@David S. Miller Sorry for the inconvenience, could you please revert it
in netdev tree?

Please submit a revert patch with the conclusions from the discussion
included in the commit message.

Okay，will do that
Thanks for the reminder

--
Cheers,
Justin (Jia He)