linux-kernel - Re: [PATCH v3 0/3] Drivers: hv: vmbus: Fix a race condition in "

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Date:   Wed, 10 Apr 2019 18:59:27 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     Kimberly Brown <kimbrownkd@...il.com>
Cc:     Michael Kelley <mikelley@...rosoft.com>,
        Long Li <longli@...rosoft.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Dexuan Cui <decui@...rosoft.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 0/3] Drivers: hv: vmbus: Fix a race condition in
 "_show" functions

On Thu, Mar 14, 2019 at 04:04:52PM -0400, Kimberly Brown wrote:
>This patchset fixes a race condition in the "_show" functions that
>access the channel ring buffers.
>
>Changes in v3:
>Patch 1: Drivers: hv: vmbus: Refactor chan->state if statement
> - Added the “reviewed-by” line from v2.
>
>Patch 2: Drivers: hv: vmbus: Set ring_info field to 0 and remove memset
> - This patch is new. This change allows the new mutex locks in patch 3
>   to be initialized when the channel is initialized.
>
>Patch 3: Drivers: hv: vmbus: Fix race condition with new
>         ring_buffer_info mutex
> - Added two ring buffer info mutex locks instead of the single channel
>   mutex lock that was proposed in v2.
> - Changed the mutex acquire/release calls as needed for the new ring
>   buffer info mutex locks.
> - Updated the commit message.
>
>
>Changes in v2:
> - In v1, I proposed using “vmbus_connection.channel_mutex” in the
>   “_show” functions to prevent the race condition. However, using this
>   mutex could result in a deadlock, so a new approach is proposed in
>   this patchset.
> - Patch 1 is new and consists of refactoring an if statement.
> - Patch 2 introduces a new mutex lock in the “vmbus_channel” struct,
>   which is used to eliminate the race condition.
>
>Kimberly Brown (3):
>  Drivers: hv: vmbus: Refactor chan->state if statement
>  Drivers: hv: vmbus: Set ring_info field to 0 and remove memset
>  Drivers: hv: vmbus: Fix race condition with new ring_buffer_info mutex
>
> drivers/hv/channel_mgmt.c |  2 +
> drivers/hv/hyperv_vmbus.h |  1 +
> drivers/hv/ring_buffer.c  | 22 ++++++++--
> drivers/hv/vmbus_drv.c    | 89 +++++++++++++++++++++++++++------------
> include/linux/hyperv.h    |  7 ++-
> 5 files changed, 88 insertions(+), 33 deletions(-)

Queued up, thanks Kimberly!

--
Thanks,
Sasha