lkml.org 
[lkml]   [2022]   [Apr]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH AUTOSEL 5.15 11/15] drivers: net: hippi: Fix deadlock in rr_close()
    Date
    From: Duoming Zhou <duoming@zju.edu.cn>

    [ Upstream commit bc6de2878429e85c1f1afaa566f7b5abb2243eef ]

    There is a deadlock in rr_close(), which is shown below:

    (Thread 1) | (Thread 2)
    | rr_open()
    rr_close() | add_timer()
    spin_lock_irqsave() //(1) | (wait a time)
    ... | rr_timer()
    del_timer_sync() | spin_lock_irqsave() //(2)
    (wait timer to stop) | ...

    We hold rrpriv->lock in position (1) of thread 1 and
    use del_timer_sync() to wait timer to stop, but timer handler
    also need rrpriv->lock in position (2) of thread 2.
    As a result, rr_close() will block forever.

    This patch extracts del_timer_sync() from the protection of
    spin_lock_irqsave(), which could let timer handler to obtain
    the needed lock.

    Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
    Link: https://lore.kernel.org/r/20220417125519.82618-1-duoming@zju.edu.cn
    Signed-off-by: Paolo Abeni <pabeni@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/net/hippi/rrunner.c | 2 ++
    1 file changed, 2 insertions(+)

    diff --git a/drivers/net/hippi/rrunner.c b/drivers/net/hippi/rrunner.c
    index 7661dbb31162..50e4bea46d67 100644
    --- a/drivers/net/hippi/rrunner.c
    +++ b/drivers/net/hippi/rrunner.c
    @@ -1353,7 +1353,9 @@ static int rr_close(struct net_device *dev)

    rrpriv->fw_running = 0;

    + spin_unlock_irqrestore(&rrpriv->lock, flags);
    del_timer_sync(&rrpriv->timer);
    + spin_lock_irqsave(&rrpriv->lock, flags);

    writel(0, &regs->TxPi);
    writel(0, &regs->IpRxPi);
    --
    2.35.1
    \
     
     \ /
      Last update: 2022-04-26 21:04    [W:6.072 / U:0.056 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site