ethernet: rocker: fix sleep in atomic context bug in neigh_timer_handler

The function neigh_timer_handler() is a timer handler that runs in an
atomic context. When used by rocker, neigh_timer_handler() calls
"kzalloc(.., GFP_KERNEL)" that may sleep. As a result, the sleep in
atomic context bug will happen. One of the processes is shown below:

ofdpa_fib4_add()
 ...
 neigh_add_timer()

(wait a timer)

neigh_timer_handler()
 neigh_release()
  neigh_destroy()
   rocker_port_neigh_destroy()
    rocker_world_port_neigh_destroy()
     ofdpa_port_neigh_destroy()
      ofdpa_port_ipv4_neigh()
       kzalloc(sizeof(.., GFP_KERNEL) //may sleep

This patch changes the gfp_t parameter of kzalloc() from GFP_KERNEL to
GFP_ATOMIC in order to mitigate the bug.

Fixes: 00fc0c51e35b ("rocker: Change world_ops API and implementation to be switchdev independant")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/rocker/rocker_ofdpa.c b/drivers/net/ethernet/rocker/rocker_ofdpa.c
index bc70c6a..58cf7cc 100644 (file)
--- a/drivers/net/ethernet/rocker/rocker_ofdpa.c
+++ b/drivers/net/ethernet/rocker/rocker_ofdpa.c
@@ -1273,7 +1273,7 @@ static int ofdpa_port_ipv4_neigh(struct ofdpa_port *ofdpa_port,
        bool removing;
        int err = 0;
 
-       entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+       entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
        if (!entry)
                return -ENOMEM;