kernel/git/stable/linux.git/net/dsa/slave.c, branch linux-5.8.y

net: dsa: link interfaces with the DSA master to get rid of lockdep warnings

2020-09-26T16:05:27+00:00

[ Upstream commit 2f1e8ea726e9020e01e9e2ae29c2d5eb11133032 ] Since commit 845e0ebb4408 ("net: change addr_list_lock back to static key"), cascaded DSA setups (DSA switch port as DSA master for another DSA switch port) are emitting this lockdep warning: ============================================ WARNING: possible recursive locking detected 5.8.0-rc1-00133-g923e4b5032dd-dirty #208 Not tainted -------------------------------------------- dhcpcd/323 is trying to acquire lock: ffff000066dd4268 (&dsa_master_addr_list_lock_key/1){+...}-{2:2}, at: dev_mc_sync+0x44/0x90 but task is already holding lock: ffff00006608c268 (&dsa_master_addr_list_lock_key/1){+...}-{2:2}, at: dev_mc_sync+0x44/0x90 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&dsa_master_addr_list_lock_key/1); lock(&dsa_master_addr_list_lock_key/1); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by dhcpcd/323: #0: ffffdbd1381dda18 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x24/0x30 #1: ffff00006614b268 (_xmit_ETHER){+...}-{2:2}, at: dev_set_rx_mode+0x28/0x48 #2: ffff00006608c268 (&dsa_master_addr_list_lock_key/1){+...}-{2:2}, at: dev_mc_sync+0x44/0x90 stack backtrace: Call trace: dump_backtrace+0x0/0x1e0 show_stack+0x20/0x30 dump_stack+0xec/0x158 __lock_acquire+0xca0/0x2398 lock_acquire+0xe8/0x440 _raw_spin_lock_nested+0x64/0x90 dev_mc_sync+0x44/0x90 dsa_slave_set_rx_mode+0x34/0x50 __dev_set_rx_mode+0x60/0xa0 dev_mc_sync+0x84/0x90 dsa_slave_set_rx_mode+0x34/0x50 __dev_set_rx_mode+0x60/0xa0 dev_set_rx_mode+0x30/0x48 __dev_open+0x10c/0x180 __dev_change_flags+0x170/0x1c8 dev_change_flags+0x2c/0x70 devinet_ioctl+0x774/0x878 inet_ioctl+0x348/0x3b0 sock_do_ioctl+0x50/0x310 sock_ioctl+0x1f8/0x580 ksys_ioctl+0xb0/0xf0 __arm64_sys_ioctl+0x28/0x38 el0_svc_common.constprop.0+0x7c/0x180 do_el0_svc+0x2c/0x98 el0_sync_handler+0x9c/0x1b8 el0_sync+0x158/0x180 Since DSA never made use of the netdev API for describing links between upper devices and lower devices, the dev->lower_level value of a DSA switch interface would be 1, which would warn when it is a DSA master. We can use netdev_upper_dev_link() to describe the relationship between a DSA slave and a DSA master. To be precise, a DSA "slave" (switch port) is an "upper" to a DSA "master" (host port). The relationship is "many uppers to one lower", like in the case of VLAN. So, for that reason, we use the same function as VLAN uses. There might be a chance that somebody will try to take hold of this interface and use it immediately after register_netdev() and before netdev_upper_dev_link(). To avoid that, we do the registration and linkage while holding the RTNL, and we use the RTNL-locked cousin of register_netdev(), which is register_netdevice(). Since this warning was not there when lockdep was using dynamic keys for addr_list_lock, we are blaming the lockdep patch itself. The network stack _has_ been using static lockdep keys before, and it _is_ likely that stacked DSA setups have been triggering these lockdep warnings since forever, however I can't test very old kernels on this particular stacked DSA setup, to ensure I'm not in fact introducing regressions. Fixes: 845e0ebb4408 ("net: change addr_list_lock back to static key") Suggested-by: Cong Wang Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2020-06-01T00:48:46+00:00

xdp_umem.c had overlapping changes between the 64-bit math fix for the calculation of npgs and the removal of the zerocopy memory type which got rid of the chunk_size_nohdr member. The mlx5 Kconfig conflict is a case where we just take the net-next copy of the Kconfig entry dependency as it takes on the ESWITCH dependency by one level of indirection which is what the 'net' conflicting change is trying to ensure. Signed-off-by: David S. Miller

net: dsa: declare lockless TX feature for slave ports

2020-05-27T22:09:28+00:00

Be there a platform with the following layout: Regular NIC | +----> DSA master for switch port | +----> DSA master for another switch port After changing DSA back to static lockdep class keys in commit 1a33e10e4a95 ("net: partially revert dynamic lockdep key changes"), this kernel splat can be seen: [ 13.361198] ============================================ [ 13.366524] WARNING: possible recursive locking detected [ 13.371851] 5.7.0-rc4-02121-gc32a05ecd7af-dirty #988 Not tainted [ 13.377874] -------------------------------------------- [ 13.383201] swapper/0/0 is trying to acquire lock: [ 13.388004] ffff0000668ff298 (&dsa_slave_netdev_xmit_lock_key){+.-.}-{2:2}, at: __dev_queue_xmit+0x84c/0xbe0 [ 13.397879] [ 13.397879] but task is already holding lock: [ 13.403727] ffff0000661a1698 (&dsa_slave_netdev_xmit_lock_key){+.-.}-{2:2}, at: __dev_queue_xmit+0x84c/0xbe0 [ 13.413593] [ 13.413593] other info that might help us debug this: [ 13.420140] Possible unsafe locking scenario: [ 13.420140] [ 13.426075] CPU0 [ 13.428523] ---- [ 13.430969] lock(&dsa_slave_netdev_xmit_lock_key); [ 13.435946] lock(&dsa_slave_netdev_xmit_lock_key); [ 13.440924] [ 13.440924] *** DEADLOCK *** [ 13.440924] [ 13.446860] May be due to missing lock nesting notation [ 13.446860] [ 13.453668] 6 locks held by swapper/0/0: [ 13.457598] #0: ffff800010003de0 ((&idev->mc_ifc_timer)){+.-.}-{0:0}, at: call_timer_fn+0x0/0x400 [ 13.466593] #1: ffffd4d3fb478700 (rcu_read_lock){....}-{1:2}, at: mld_sendpack+0x0/0x560 [ 13.474803] #2: ffffd4d3fb478728 (rcu_read_lock_bh){....}-{1:2}, at: ip6_finish_output2+0x64/0xb10 [ 13.483886] #3: ffffd4d3fb478728 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x6c/0xbe0 [ 13.492793] #4: ffff0000661a1698 (&dsa_slave_netdev_xmit_lock_key){+.-.}-{2:2}, at: __dev_queue_xmit+0x84c/0xbe0 [ 13.503094] #5: ffffd4d3fb478728 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x6c/0xbe0 [ 13.512000] [ 13.512000] stack backtrace: [ 13.516369] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.7.0-rc4-02121-gc32a05ecd7af-dirty #988 [ 13.530421] Call trace: [ 13.532871] dump_backtrace+0x0/0x1d8 [ 13.536539] show_stack+0x24/0x30 [ 13.539862] dump_stack+0xe8/0x150 [ 13.543271] __lock_acquire+0x1030/0x1678 [ 13.547290] lock_acquire+0xf8/0x458 [ 13.550873] _raw_spin_lock+0x44/0x58 [ 13.554543] __dev_queue_xmit+0x84c/0xbe0 [ 13.558562] dev_queue_xmit+0x24/0x30 [ 13.562232] dsa_slave_xmit+0xe0/0x128 [ 13.565988] dev_hard_start_xmit+0xf4/0x448 [ 13.570182] __dev_queue_xmit+0x808/0xbe0 [ 13.574200] dev_queue_xmit+0x24/0x30 [ 13.577869] neigh_resolve_output+0x15c/0x220 [ 13.582237] ip6_finish_output2+0x244/0xb10 [ 13.586430] __ip6_finish_output+0x1dc/0x298 [ 13.590709] ip6_output+0x84/0x358 [ 13.594116] mld_sendpack+0x2bc/0x560 [ 13.597786] mld_ifc_timer_expire+0x210/0x390 [ 13.602153] call_timer_fn+0xcc/0x400 [ 13.605822] run_timer_softirq+0x588/0x6e0 [ 13.609927] __do_softirq+0x118/0x590 [ 13.613597] irq_exit+0x13c/0x148 [ 13.616918] __handle_domain_irq+0x6c/0xc0 [ 13.621023] gic_handle_irq+0x6c/0x160 [ 13.624779] el1_irq+0xbc/0x180 [ 13.627927] cpuidle_enter_state+0xb4/0x4d0 [ 13.632120] cpuidle_enter+0x3c/0x50 [ 13.635703] call_cpuidle+0x44/0x78 [ 13.639199] do_idle+0x228/0x2c8 [ 13.642433] cpu_startup_entry+0x2c/0x48 [ 13.646363] rest_init+0x1ac/0x280 [ 13.649773] arch_call_rest_init+0x14/0x1c [ 13.653878] start_kernel+0x490/0x4bc Lockdep keys themselves were added in commit ab92d68fc22f ("net: core: add generic lockdep keys"), and it's very likely that this splat existed since then, but I have no real way to check, since this stacked platform wasn't supported by mainline back then. >From Taehee's own words: This patch was considered that all stackable devices have LLTX flag. But the dsa doesn't have LLTX, so this splat happened. After this patch, dsa shares the same lockdep class key. On the nested dsa interface architecture, which you illustrated, the same lockdep class key will be used in __dev_queue_xmit() because dsa doesn't have LLTX. So that lockdep detects deadlock because the same lockdep class key is used recursively although actually the different locks are used. There are some ways to fix this problem. 1. using NETIF_F_LLTX flag. If possible, using the LLTX flag is a very clear way for it. But I'm so sorry I don't know whether the dsa could have LLTX or not. 2. using dynamic lockdep again. It means that each interface uses a separate lockdep class key. So, lockdep will not detect recursive locking. But this way has a problem that it could consume lockdep class key too many. Currently, lockdep can have 8192 lockdep class keys. - you can see this number with the following command. cat /proc/lockdep_stats lock-classes: 1251 [max: 8192] ... The [max: 8192] means that the maximum number of lockdep class keys. If too many lockdep class keys are registered, lockdep stops to work. So, using a dynamic(separated) lockdep class key should be considered carefully. In addition, updating lockdep class key routine might have to be existing. (lockdep_register_key(), lockdep_set_class(), lockdep_unregister_key()) 3. Using lockdep subclass. A lockdep class key could have 8 subclasses. The different subclass is considered different locks by lockdep infrastructure. But "lock-classes" is not counted by subclasses. So, it could avoid stopping lockdep infrastructure by an overflow of lockdep class keys. This approach should also have an updating lockdep class key routine. (lockdep_set_subclass()) 4. Using nonvalidate lockdep class key. The lockdep infrastructure supports nonvalidate lockdep class key type. It means this lockdep is not validated by lockdep infrastructure. So, the splat will not happen but lockdep couldn't detect real deadlock case because lockdep really doesn't validate it. I think this should be used for really special cases. (lockdep_set_novalidate_class()) Further discussion here: https://patchwork.ozlabs.org/project/netdev/patch/20200503052220.4536-2-xiyou.wangcong@gmail.com/ There appears to be no negative side-effect to declaring lockless TX for the DSA virtual interfaces, which means they handle their own locking. So that's what we do to make the splat go away. Patch tested in a wide variety of cases: unicast, multicast, PTP, etc. Fixes: ab92d68fc22f ("net: core: add generic lockdep keys") Suggested-by: Taehee Yoo Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

net: dsa: provide an option for drivers to always receive bridge VLANs

2020-05-12T20:08:07+00:00

DSA assumes that a bridge which has vlan filtering disabled is not vlan aware, and ignores all vlan configuration. However, the kernel software bridge code allows configuration in this state. This causes the kernel's idea of the bridge vlan state and the hardware state to disagree, so "bridge vlan show" indicates a correct configuration but the hardware lacks all configuration. Even worse, enabling vlan filtering on a DSA bridge immediately blocks all traffic which, given the output of "bridge vlan show", is very confusing. Provide an option that drivers can set to indicate they want to receive vlan configuration even when vlan filtering is disabled. At the very least, this is safe for Marvell DSA bridges, which do not look up ingress traffic in the VTU if the port is in 8021Q disabled state. It is also safe for the Ocelot switch family. Whether this change is suitable for all DSA bridges is not known. Signed-off-by: Russell King Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

netpoll: accept NULL np argument in netpoll_send_skb()

2020-05-08T01:11:07+00:00

netpoll_send_skb() callers seem to leak skb if the np pointer is NULL. While this should not happen, we can make the code more robust. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

net: remove newlines in NL_SET_ERR_MSG_MOD

2020-05-08T00:56:14+00:00

The NL_SET_ERR_MSG_MOD macro is used to report a string describing an error message to userspace via the netlink extended ACK structure. It should not have a trailing newline. Add a cocci script which catches cases where the newline marker is present. Using this script, fix the handful of cases which accidentally included a trailing new line. I couldn't figure out a way to get a patch mode working, so this script only implements context, report, and org. Signed-off-by: Jacob Keller Cc: Jakub Kicinski Cc: Andy Whitcroft Cc: Joe Perches Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2020-05-07T05:10:13+00:00

Conflicts were all overlapping changes. Signed-off-by: David S. Miller

net: dsa: remove duplicate assignment in dsa_slave_add_cls_matchall_mirred

2020-05-07T00:30:35+00:00

This was caused by a poor merge conflict resolution on my side. The "act = &cls->rule->action.entries[0];" assignment was already present in the code prior to the patch mentioned below. Fixes: e13c2075280e ("net: dsa: refactor matchall mirred action to separate function") Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: partially revert dynamic lockdep key changes

2020-05-04T19:05:56+00:00

This patch reverts the folowing commits: commit 064ff66e2bef84f1153087612032b5b9eab005bd "bonding: add missing netdev_update_lockdep_key()" commit 53d374979ef147ab51f5d632dfe20b14aebeccd0 "net: avoid updating qdisc_xmit_lock_key in netdev_update_lockdep_key()" commit 1f26c0d3d24125992ab0026b0dab16c08df947c7 "net: fix kernel-doc warning in " commit ab92d68fc22f9afab480153bd82a20f6e2533769 "net: core: add generic lockdep keys" but keeps the addr_list_lock_key because we still lock addr_list_lock nestedly on stack devices, unlikely xmit_lock this is safe because we don't take addr_list_lock on any fast path. Reported-and-tested-by: syzbot+aaa6fa4949cc5d9b7b25@syzkaller.appspotmail.com Cc: Dmitry Vyukov Cc: Taehee Yoo Signed-off-by: Cong Wang Acked-by: Taehee Yoo Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2020-04-26T03:18:53+00:00

Simple overlapping changes to linux/vermagic.h Signed-off-by: David S. Miller