From: Michael Ellerman Date: Fri, 24 Apr 2015 05:52:32 +0000 (+1000) Subject: ehea: Fix memory hook reference counting crashes X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=3051f39253680624504021fd3b29fc621a4fd6b6;p=linux-beck.git ehea: Fix memory hook reference counting crashes The recent commit to only register the EHEA memory hotplug hooks on adapter probe has a few problems. Firstly the reference counting is wrong for multiple adapters, in that the hooks are registered multiple times. Secondly the check in the tear down path is backward. Finally the error path doesn't decrement the count. The multiple registration of the hooks is the biggest problem, as it leads to oopses when the system is rebooted, and/or errors during memory hotplug, eg: $ ./mem-on-off-test.sh -r 2 ... ehea: memory is going offline ehea: LPAR memory changed - re-initializing driver ehea: re-initializing driver complete ehea: memory is going offline ehea: LPAR memory changed - re-initializing driver ehea: opcode=26c ret=fffffffffffffffc arg1=8000000003000003 arg2=0 arg3=700000060000d600 arg4=3fded0000 arg5=200 arg6=0 arg7=0 ehea: register_rpage_mr failed ehea: registering mr failed ehea: register MR failed - driver inoperable! ehea: memory is going offline Fixes: aa183323312d ("ehea: Register memory hotplug, reboot and crash hooks on adapter probe") Signed-off-by: Michael Ellerman Signed-off-by: David S. Miller --- diff --git a/drivers/net/ethernet/ibm/ehea/ehea_main.c b/drivers/net/ethernet/ibm/ehea/ehea_main.c index 291c87036e17..2a0dc127df3f 100644 --- a/drivers/net/ethernet/ibm/ehea/ehea_main.c +++ b/drivers/net/ethernet/ibm/ehea/ehea_main.c @@ -3347,7 +3347,7 @@ static int ehea_register_memory_hooks(void) { int ret = 0; - if (atomic_inc_and_test(&ehea_memory_hooks_registered)) + if (atomic_inc_return(&ehea_memory_hooks_registered) > 1) return 0; ret = ehea_create_busmap(); @@ -3381,12 +3381,14 @@ out3: out2: unregister_reboot_notifier(&ehea_reboot_nb); out: + atomic_dec(&ehea_memory_hooks_registered); return ret; } static void ehea_unregister_memory_hooks(void) { - if (atomic_read(&ehea_memory_hooks_registered)) + /* Only remove the hooks if we've registered them */ + if (atomic_read(&ehea_memory_hooks_registered) == 0) return; unregister_reboot_notifier(&ehea_reboot_nb);