From: Davide Caratti dcaratti@redhat.com
[ Upstream commit 04d37cf46a773910f75fefaa9f9488f42bfe1fe2 ]
Now that 'TCQ_F_CPUSTATS' bit can be cleared, depending on the value of 'TCQ_F_NOLOCK' bit in the parent qdisc, we need to be sure that per-cpu counters are present when 'reset()' is called for pfifo_fast qdiscs. Otherwise, the following script:
# tc q a dev lo handle 1: root htb default 100 # tc c a dev lo parent 1: classid 1:100 htb \
rate 95Mbit ceil 100Mbit burst 64k
[...] # tc f a dev lo parent 1: protocol arp basic classid 1:100 [...] # tc q a dev lo parent 1:100 handle 100: pfifo_fast [...] # tc q d dev lo root
can generate the following splat:
Unable to handle kernel paging request at virtual address dfff2c01bd148000 Mem abort info: ESR = 0x96000004 Exception class = DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 Data abort info: ISV = 0, ISS = 0x00000004 CM = 0, WnR = 0 [dfff2c01bd148000] address between user and kernel address ranges Internal error: Oops: 96000004 [#1] SMP [...] pstate: 80000005 (Nzcv daif -PAN -UAO) pc : pfifo_fast_reset+0x280/0x4d8 lr : pfifo_fast_reset+0x21c/0x4d8 sp : ffff800d09676fa0 x29: ffff800d09676fa0 x28: ffff200012ee22e4 x27: dfff200000000000 x26: 0000000000000000 x25: ffff800ca0799958 x24: ffff1001940f332b x23: 0000000000000007 x22: ffff200012ee1ab8 x21: 0000600de8a40000 x20: 0000000000000000 x19: ffff800ca0799900 x18: 0000000000000000 x17: 0000000000000002 x16: 0000000000000000 x15: 0000000000000000 x14: 0000000000000000 x13: 0000000000000000 x12: ffff1001b922e6e2 x11: 1ffff001b922e6e1 x10: 0000000000000000 x9 : 1ffff001b922e6e1 x8 : dfff200000000000 x7 : 0000000000000000 x6 : 0000000000000000 x5 : 1fffe400025dc45c x4 : 1fffe400025dc357 x3 : 00000c01bd148000 x2 : 0000600de8a40000 x1 : 0000000000000007 x0 : 0000600de8a40004 Call trace: pfifo_fast_reset+0x280/0x4d8 qdisc_reset+0x6c/0x370 htb_reset+0x150/0x3b8 [sch_htb] qdisc_reset+0x6c/0x370 dev_deactivate_queue.constprop.5+0xe0/0x1a8 dev_deactivate_many+0xd8/0x908 dev_deactivate+0xe4/0x190 qdisc_graft+0x88c/0xbd0 tc_get_qdisc+0x418/0x8a8 rtnetlink_rcv_msg+0x3a8/0xa78 netlink_rcv_skb+0x18c/0x328 rtnetlink_rcv+0x28/0x38 netlink_unicast+0x3c4/0x538 netlink_sendmsg+0x538/0x9a0 sock_sendmsg+0xac/0xf8 ___sys_sendmsg+0x53c/0x658 __sys_sendmsg+0xc8/0x140 __arm64_sys_sendmsg+0x74/0xa8 el0_svc_handler+0x164/0x468 el0_svc+0x10/0x14 Code: 910012a0 92400801 d343fc03 11000c21 (38fb6863)
Fix this by testing the value of 'TCQ_F_CPUSTATS' bit in 'qdisc->flags', before dereferencing 'qdisc->cpu_qstats'.
Changes since v1: - coding style improvements, thanks to Stefano Brivio
Fixes: 8a53e616de29 ("net: sched: when clearing NOLOCK, clear TCQ_F_CPUSTATS, too") CC: Paolo Abeni pabeni@redhat.com Reported-by: Li Shuang shuali@redhat.com Signed-off-by: Davide Caratti dcaratti@redhat.com Acked-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Stefano Brivio sbrivio@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sched/sch_generic.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
--- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -692,11 +692,14 @@ static void pfifo_fast_reset(struct Qdis kfree_skb(skb); }
- for_each_possible_cpu(i) { - struct gnet_stats_queue *q = per_cpu_ptr(qdisc->cpu_qstats, i); + if (qdisc_is_percpu_stats(qdisc)) { + for_each_possible_cpu(i) { + struct gnet_stats_queue *q;
- q->backlog = 0; - q->qlen = 0; + q = per_cpu_ptr(qdisc->cpu_qstats, i); + q->backlog = 0; + q->qlen = 0; + } } }