[PATCH 5/6] net: dsa: Do not reschedule polling if driver removed

Do not reschedule the delayed work used for polling when
the driver is removed, by testing the 'poll_link_needed'
flag.
Avoids this crash:
 dsa dsa ethmv2 (unregistering): Link is Down
 device eth1 left promiscuous mode
 Unable to handle kernel paging request at virtual address bacc5cf6
 ...
 (run_timer_softirq) from [<c003e810>] (__do_softirq+0xcc/0x320)
 (__do_softirq) from [<c003ed40>] (irq_exit+0xac/0x10c)
 (irq_exit) from [<c007ec20>] (__handle_domain_irq+0x50/0xa8)

Signed-off-by: Frode Isaksen <redacted>
Signed-off-by: Neil Armstrong <redacted>
---
 net/dsa/dsa.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 9240a46..9881b17 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c

@@ -526,7 +526,8 @@ static void dsa_link_poll_work(struct work_struct *ugly)
 			ds->drv->poll_link(ds);
 	}

-	schedule_delayed_work(&dst->link_poll_work, round_jiffies_relative(HZ));
+	if (dst->link_poll_needed)
+		schedule_delayed_work(&dst->link_poll_work, round_jiffies_relative(HZ));
 }

 /* platform driver init and cleanup *****************************************/

@@ -949,6 +950,7 @@ static void dsa_remove_dst(struct dsa_switch_tree *dst)
 	int i;

 	if (dst->link_poll_needed) {
+		dst->link_poll_needed = 0;
 		cancel_delayed_work_sync(&dst->link_poll_work);
 		flush_delayed_work(&dst->link_poll_work);
 	}

-- 
1.9.1