| Message ID | 20180619153950.28903-1-denkenz@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Johannes Berg |
| Headers | show |
On 6/19/2018 5:39 PM, Denis Kenzior wrote: > On pre-emption enabled kernels the following oops was being seen due > to missing local_bh_disable/local_bh_enable calls. mac80211 assumes > that pre-emption is disabled in the data path. No sure if "assumes" is the right term here. It seems like it is required and there is probably a good reason for that. Would be nice to know what that reason is. Regards, Arend
On Wed, 2018-06-20 at 09:51 +0200, Arend van Spriel wrote: > On 6/19/2018 5:39 PM, Denis Kenzior wrote: > > On pre-emption enabled kernels the following oops was being seen due > > to missing local_bh_disable/local_bh_enable calls. mac80211 assumes > > that pre-emption is disabled in the data path. > > No sure if "assumes" is the right term here. It seems like it is > required and there is probably a good reason for that. Would be nice to > know what that reason is. It's using per-CPU data. johannes
On 6/20/2018 9:53 AM, Johannes Berg wrote: > On Wed, 2018-06-20 at 09:51 +0200, Arend van Spriel wrote: >> On 6/19/2018 5:39 PM, Denis Kenzior wrote: >>> On pre-emption enabled kernels the following oops was being seen due >>> to missing local_bh_disable/local_bh_enable calls. mac80211 assumes >>> that pre-emption is disabled in the data path. >> >> No sure if "assumes" is the right term here. It seems like it is >> required and there is probably a good reason for that. Would be nice to >> know what that reason is. > > It's using per-CPU data. Hence the smp_processor_id() call which Denis mentioned in the bug report? Regards, Arend
On Wed, 2018-06-20 at 09:54 +0200, Arend van Spriel wrote: > On 6/20/2018 9:53 AM, Johannes Berg wrote: > > On Wed, 2018-06-20 at 09:51 +0200, Arend van Spriel wrote: > > > On 6/19/2018 5:39 PM, Denis Kenzior wrote: > > > > On pre-emption enabled kernels the following oops was being seen due > > > > to missing local_bh_disable/local_bh_enable calls. mac80211 assumes > > > > that pre-emption is disabled in the data path. > > > > > > No sure if "assumes" is the right term here. It seems like it is > > > required and there is probably a good reason for that. Would be nice to > > > know what that reason is. > > > > It's using per-CPU data. > > Hence the smp_processor_id() call which Denis mentioned in the bug report? Yeah, I think that's an implementation detail thereof. johannes
On Tue, 2018-06-19 at 10:39 -0500, Denis Kenzior wrote: > On pre-emption enabled kernels the following oops was being seen due to > missing local_bh_disable/local_bh_enable calls. mac80211 assumes that > pre-emption is disabled in the data path. Applied, but I've done some major edits to the commit message and added a Fixes tag :) johannes
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index 5b93bde248fd..6a79d564de35 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -4850,7 +4850,9 @@ int ieee80211_tx_control_port(struct wiphy *wiphy, struct net_device *dev, skb_reset_network_header(skb); skb_reset_mac_header(skb); + local_bh_disable(); __ieee80211_subif_start_xmit(skb, skb->dev, flags); + local_bh_enable(); return 0; }
On pre-emption enabled kernels the following oops was being seen due to missing local_bh_disable/local_bh_enable calls. mac80211 assumes that pre-emption is disabled in the data path. [ 5365.229756] Call Trace: [ 5365.229762] dump_stack+0x5c/0x80 [ 5365.229766] check_preemption_disabled.cold.0+0x46/0x51 [ 5365.229779] __ieee80211_subif_start_xmit+0x144/0x210 [mac80211] [ 5365.229790] ieee80211_tx_control_port+0x116/0x140 [mac80211] [ 5365.229806] nl80211_tx_control_port+0x13c/0x270 [cfg80211] [ 5365.229810] genl_family_rcv_msg+0x1c4/0x3a0 [ 5365.229814] ? nlmon_xmit+0x3c/0x50 [nlmon] [ 5365.229816] ? dev_hard_start_xmit+0xa5/0x240 [ 5365.229817] genl_rcv_msg+0x47/0x90 [ 5365.229818] ? genl_family_rcv_msg+0x3a0/0x3a0 [ 5365.229820] netlink_rcv_skb+0x4c/0x120 [ 5365.229821] genl_rcv+0x24/0x40 [ 5365.229822] netlink_unicast+0x196/0x240 [ 5365.229824] netlink_sendmsg+0x1fd/0x3c0 [ 5365.229826] sock_sendmsg+0x33/0x40 [ 5365.229827] __sys_sendto+0xee/0x160 [ 5365.229830] ? __se_sys_epoll_ctl+0x34d/0xe80 [ 5365.229831] ? do_epoll_wait+0xb0/0xd0 [ 5365.229832] __x64_sys_sendto+0x24/0x30 [ 5365.229835] do_syscall_64+0x5b/0x170 [ 5365.229836] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Signed-off-by: Denis Kenzior <denkenz@gmail.com> --- net/mac80211/tx.c | 2 ++ 1 file changed, 2 insertions(+)