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    Subject[PATCH 1/1] rapidio/rio_cm: avoid GFP_KERNEL in atomic context
    Date
    As reported by Alexey Khoroshilov <khoroshilov@ispras.ru>
    (see https://lkml.org/lkml/2016/9/9/737):
    riocm_send_close() is called from rio_cm_shutdown() under
    spin_lock_bh(idr_lock), but riocm_send_close() uses a GFP_KERNEL
    allocation.

    Fix by taking riocm_send_close() outside of spinlock protected code.

    Reported-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
    Cc: Alexey Khoroshilov <khoroshilov@ispras.ru>
    Cc: linux-kernel@vger.kernel.org
    Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
    ---
    drivers/rapidio/rio_cm.c | 20 +++++++++++++++++---
    1 file changed, 17 insertions(+), 3 deletions(-)

    diff --git a/drivers/rapidio/rio_cm.c b/drivers/rapidio/rio_cm.c
    index 3226983..0e91335 100644
    --- a/drivers/rapidio/rio_cm.c
    +++ b/drivers/rapidio/rio_cm.c
    @@ -2242,17 +2242,31 @@ static int rio_cm_shutdown(struct notifier_block *nb, unsigned long code,
    {
    struct rio_channel *ch;
    unsigned int i;
    + LIST_HEAD(list);

    riocm_debug(EXIT, ".");

    + /*
    + * If there are any channels left in connected state send
    + * close notification to the connection partner.
    + * First build a list of channels that require a closing
    + * notification because function riocm_send_close() should
    + * be called outside of spinlock protected code.
    + */
    spin_lock_bh(&idr_lock);
    idr_for_each_entry(&ch_idr, ch, i) {
    - riocm_debug(EXIT, "close ch %d", ch->id);
    - if (ch->state == RIO_CM_CONNECTED)
    - riocm_send_close(ch);
    + if (ch->state == RIO_CM_CONNECTED) {
    + riocm_debug(EXIT, "close ch %d", ch->id);
    + idr_remove(&ch_idr, ch->id);
    + list_add(&ch->ch_node, &list);
    + }
    }
    spin_unlock_bh(&idr_lock);

    + if (!list_empty(&list))
    + list_for_each_entry(ch, &list, ch_node)
    + riocm_send_close(ch);
    +
    return NOTIFY_DONE;
    }

    --
    2.9.0
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