leaf classes of ETS qdiscs are served in strict priority or deficit round
robin (DRR), depending on the value of 'nstrict'. Since this value can be
changed while traffic is running, we need to be sure that the active list
of DRR classes can be updated at any time, so:
1) call INIT_LIST_HEAD(&alist) on all leaf classes in .init(), before the
first packet hits any of them.
2) ensure that 'alist' is not overwritten with zeros when a leaf class is
no more strict priority nor DRR (i.e. array elements beyond 'nbands').
Link: https://lore.kernel.org/netdev/YS%2FoZ+f0Nr8eQkzH@dcaratti.users.ipa.redhat.com
Suggested-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
While running kselftests, Hangbin observed that sch_ets.sh often crashes,
and splats like the following one are seen in the output of 'dmesg':
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 159f12067 P4D 159f12067 PUD 159f13067 PMD 0
Oops: 0000 [#1] SMP NOPTI
CPU: 2 PID: 921 Comm: tc Not tainted 5.14.0-rc6+ #458
Hardware name: Red Hat KVM, BIOS 1.11.1-4.module+el8.1.0+4066+0f1aadab 04/01/2014
RIP: 0010:__list_del_entry_valid+0x2d/0x50
Code: 48 8b 57 08 48 b9 00 01 00 00 00 00 ad de 48 39 c8 0f 84 ac 6e 5b 00 48 b9 22 01 00 00 00 00 ad de 48 39 ca 0f 84 cf 6e 5b 00 <48> 8b 32 48 39 fe 0f 85 af 6e 5b 00 48 8b 50 08 48 39 f2 0f 85 94
RSP: 0018:ffffb2da005c3890 EFLAGS: 00010217
RAX: 0000000000000000 RBX: ffff9073ba23f800 RCX: dead000000000122
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff9073ba23fbc8
RBP: ffff9073ba23f890 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000001 R12: dead000000000100
R13: ffff9073ba23fb00 R14: 0000000000000002 R15: 0000000000000002
FS: 00007f93e5564e40(0000) GS:ffff9073bba00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000014ad34000 CR4: 0000000000350ee0
Call Trace:
ets_qdisc_reset+0x6e/0x100 [sch_ets]
qdisc_reset+0x49/0x1d0
tbf_reset+0x15/0x60 [sch_tbf]
qdisc_reset+0x49/0x1d0
dev_reset_queue.constprop.42+0x2f/0x90
dev_deactivate_many+0x1d3/0x3d0
dev_deactivate+0x56/0x90
qdisc_graft+0x47e/0x5a0
tc_get_qdisc+0x1db/0x3e0
rtnetlink_rcv_msg+0x164/0x4c0
netlink_rcv_skb+0x50/0x100
netlink_unicast+0x1a5/0x280
netlink_sendmsg+0x242/0x480
sock_sendmsg+0x5b/0x60
____sys_sendmsg+0x1f2/0x260
___sys_sendmsg+0x7c/0xc0
__sys_sendmsg+0x57/0xa0
do_syscall_64+0x3a/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f93e44b8338
Code: 89 02 48 c7 c0 ff ff ff ff eb b5 0f 1f 80 00 00 00 00 f3 0f 1e fa 48 8d 05 25 43 2c 00 8b 00 85 c0 75 17 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 41 54 41 89 d4 55
RSP: 002b:00007ffc0db737a8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000061255c06 RCX: 00007f93e44b8338
RDX: 0000000000000000 RSI: 00007ffc0db73810 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 000000000000000b R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000687880 R14: 0000000000000000 R15: 0000000000000000
Modules linked in: sch_ets sch_tbf dummy rfkill iTCO_wdt iTCO_vendor_support intel_rapl_msr intel_rapl_common joydev i2c_i801 pcspkr i2c_smbus lpc_ich virtio_balloon ip_tables xfs libcrc32c crct10dif_pclmul crc32_pclmul crc32c_intel ahci libahci ghash_clmulni_intel libata serio_raw virtio_blk virtio_console virtio_net net_failover failover sunrpc dm_mirror dm_region_hash dm_log dm_mod
CR2: 0000000000000000
When the change() function decreases the value of 'nstrict', we must take
into account that packets might be already enqueued on a class that flips
from 'strict' to 'quantum': otherwise that class will not be added to the
bandwidth-sharing list. Then, a call to ets_qdisc_reset() will attempt to
do list_del(&alist) with 'alist' filled with zero, hence the NULL pointer
dereference.
For classes flipping from 'strict' to 'quantum', initialize an empty list
and eventually add it to the bandwidth-sharing list, if there are packets
already enqueued. In this way, the kernel will:
a) prevent crashing as described above.
b) avoid retaining the backlog packets (for an arbitrarily long time) in
case no packet is enqueued after a change from 'strict' to 'quantum'.
Reported-by: Hangbin Liu <liuhangbin@gmail.com>
Fixes: dcc68b4d80 ("net: sch_ets: Add a new Qdisc")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
currently, only 'ingress' and 'clsact ingress' qdiscs store the tc 'chain
id' in the skb extension. However, userspace programs (like ovs) are able
to setup egress rules, and datapath gets confused in case it doesn't find
the 'chain id' for a packet that's "recirculated" by tc.
Change tcf_classify() to have the same semantic as tcf_classify_ingress()
so that a single function can be called in ingress / egress, using the tc
ingress / egress block respectively.
Suggested-by: Alaa Hleilel <alaa@nvidia.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
A following patch introduces qevents, points in qdisc algorithm where
packet can be processed by user-defined filters. Should this processing
lead to a situation where a new packet is to be enqueued on the same port,
holding the root lock would lead to deadlocks. To solve the issue, qevent
handler needs to unlock and relock the root lock when necessary.
To that end, add the root lock argument to the qdisc op enqueue, and
propagate throughout.
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add hooks at appropriate points to make it possible to offload the ETS
Qdisc.
Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Introduces a new Qdisc, which is based on 802.1Q-2014 wording. It is
PRIO-like in how it is configured, meaning one needs to specify how many
bands there are, how many are strict and how many are dwrr, quanta for the
latter, and priomap.
The new Qdisc operates like the PRIO / DRR combo would when configured as
per the standard. The strict classes, if any, are tried for traffic first.
When there's no traffic in any of the strict queues, the ETS ones (if any)
are treated in the same way as in DRR.
Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
