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    Subject[ 032/104] netconsole: dont call __netpoll_cleanup() while atomic
    3.2-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Veaceslav Falico <vfalico@redhat.com>

    [ Upstream commit 3f315bef23075ea8a98a6fe4221a83b83456d970 ]

    __netpoll_cleanup() is called in netconsole_netdev_event() while holding a
    spinlock. Release/acquire the spinlock before/after it and restart the
    loop. Also, disable the netconsole completely, because we won't have chance
    after the restart of the loop, and might end up in a situation where
    nt->enabled == 1 and nt->np.dev == NULL.

    Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
    Acked-by: Neil Horman <nhorman@tuxdriver.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    drivers/net/netconsole.c | 20 +++++++++-----------
    1 file changed, 9 insertions(+), 11 deletions(-)

    diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
    index 01b104e..bff6908 100644
    --- a/drivers/net/netconsole.c
    +++ b/drivers/net/netconsole.c
    @@ -630,6 +630,7 @@ static int netconsole_netdev_event(struct notifier_block *this,
    goto done;

    spin_lock_irqsave(&target_list_lock, flags);
    +restart:
    list_for_each_entry(nt, &target_list, list) {
    netconsole_target_get(nt);
    if (nt->np.dev == dev) {
    @@ -642,20 +643,17 @@ static int netconsole_netdev_event(struct notifier_block *this,
    case NETDEV_UNREGISTER:
    /*
    * rtnl_lock already held
    + * we might sleep in __netpoll_cleanup()
    */
    - if (nt->np.dev) {
    - spin_unlock_irqrestore(
    - &target_list_lock,
    - flags);
    - __netpoll_cleanup(&nt->np);
    - spin_lock_irqsave(&target_list_lock,
    - flags);
    - dev_put(nt->np.dev);
    - nt->np.dev = NULL;
    - }
    + spin_unlock_irqrestore(&target_list_lock, flags);
    + __netpoll_cleanup(&nt->np);
    + spin_lock_irqsave(&target_list_lock, flags);
    + dev_put(nt->np.dev);
    + nt->np.dev = NULL;
    nt->enabled = 0;
    stopped = true;
    - break;
    + netconsole_target_put(nt);
    + goto restart;
    }
    }
    netconsole_target_put(nt);



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