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xen-netfront: fix two hotplug related issues

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This patch fixes two issues seen on hot-unplug. The first one is a panic
caused by calling ether_ifdetach after freeing the internal netfront queue
structures. ether_ifdetach will call xn_qflush, and this needs to be done
before freeing the queues. This prevents the following panic:

Fatal trap 9: general protection fault while in kernel mode
cpuid = 2; apic id = 04
instruction pointer	= 0x20:0xffffffff80b1687f
stack pointer	        = 0x28:0xfffffe009239e770
frame pointer	        = 0x28:0xfffffe009239e780
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 0 (thread taskq)
[ thread pid 0 tid 100015 ]
Stopped at      strlen+0x1f:    movq    (%rcx),%rax
db> bt
Tracing pid 0 tid 100015 td 0xfffff800038a6000
strlen() at strlen+0x1f/frame 0xfffffe009239e780
kvprintf() at kvprintf+0xfa0/frame 0xfffffe009239e890
vsnprintf() at vsnprintf+0x31/frame 0xfffffe009239e8b0
kassert_panic() at kassert_panic+0x5a/frame 0xfffffe009239e920
__mtx_lock_flags() at __mtx_lock_flags+0x164/frame 0xfffffe009239e970
xn_qflush() at xn_qflush+0x59/frame 0xfffffe009239e9b0
if_detach() at if_detach+0x17e/frame 0xfffffe009239ea10
netif_free() at netif_free+0x97/frame 0xfffffe009239ea30
netfront_detach() at netfront_detach+0x11/frame 0xfffffe009239ea40
[...]

Another panic can be triggered by hot-plugging a NIC:

Fatal trap 18: integer divide fault while in kernel mode
cpuid = 0; apic id = 00
instruction pointer	= 0x20:0xffffffff80902203
stack pointer	        = 0x28:0xfffffe00508d3660
frame pointer	        = 0x28:0xfffffe00508d36a0
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 2960 (ifconfig)
[ thread pid 2960 tid 100088 ]
Stopped at      xn_txq_mq_start+0x33:   divl    %esi,%eax
db> bt
Tracing pid 2960 tid 100088 td 0xfffff8000850aa00
xn_txq_mq_start() at xn_txq_mq_start+0x33/frame 0xfffffe00508d36a0
ether_output() at ether_output+0x570/frame 0xfffffe00508d3720
arprequest() at arprequest+0x433/frame 0xfffffe00508d3820
arp_ifinit() at arp_ifinit+0x49/frame 0xfffffe00508d3850
xn_ioctl() at xn_ioctl+0x1a2/frame 0xfffffe00508d3890
in_control() at in_control+0x882/frame 0xfffffe00508d3910
ifioctl() at ifioctl+0xda1/frame 0xfffffe00508d39a0
kern_ioctl() at kern_ioctl+0x246/frame 0xfffffe00508d3a00
sys_ioctl() at sys_ioctl+0x171/frame 0xfffffe00508d3ae0
amd64_syscall() at amd64_syscall+0x2db/frame 0xfffffe00508d3bf0
Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe00508d3bf0
--- syscall (54, FreeBSD ELF64, sys_ioctl), rip = 0x8011e185a, rsp =
0x7fffffffe478, rbp = 0x7fffffffe4c0 ---

This is caused by marking the driver as active before it's fully
initialized, and thus calling xn_txq_mq_start with num_queues set to 0.

Reviewed by:		Wei Liu <wei.liu2@citrix.com>
Sponsored by:		Citrix Systems R&D
Differential revision:	https://reviews.freebsd.org/D6646
This commit is contained in:
Roger Pau Monné 2016-06-02 11:18:02 +00:00
parent da695b059d
commit c21b47d8c9
1 changed files with 4 additions and 2 deletions
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6
sys/dev/xen/netfront/netfront.c
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@ -1704,7 +1704,7 @@ xn_ifinit_locked(struct netfront_info *np)
ifp = np->xn_ifp;
if (ifp->if_drv_flags & IFF_DRV_RUNNING)
if (ifp->if_drv_flags & IFF_DRV_RUNNING || !netfront_carrier_ok(np))
return;
xn_stop(np);
@ -2088,6 +2088,8 @@ xn_txq_mq_start(struct ifnet *ifp, struct mbuf *m)
np = ifp->if_softc;
npairs = np->num_queues;
KASSERT(npairs != 0, ("called with 0 available queues"));
/* check if flowid is set */
if (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE)
i = m->m_pkthdr.flowid % npairs;
@ -2202,9 +2204,9 @@ netif_free(struct netfront_info *np)
xn_stop(np);
XN_UNLOCK(np);
netif_disconnect_backend(np);
ether_ifdetach(np->xn_ifp);
free(np->rxq, M_DEVBUF);
free(np->txq, M_DEVBUF);
ether_ifdetach(np->xn_ifp);
if_free(np->xn_ifp);
np->xn_ifp = NULL;
ifmedia_removeall(&np->sc_media);