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There is a long standing problem with multicast programming for NICs

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and IPv6.  With IPv6 we may call if_addmulti() in context of processing
of an incoming packet.  Usually this is interrupt context.  While most
of the NIC drivers are able to reprogram multicast filters without
sleeping, some of them can't.  An example is e1000 family of drivers.
With iflib conversion the problem was somewhat hidden.  Iflib processes
packets in private taskqueue, so going to sleep doesn't trigger an
assertion.  However, the sleep would block operation of the driver and
following incoming packets would fill the ring and eventually would
start being dropped.  Enabling epoch for the full time of a packet
processing again started to trigger assertions for e1000.

Fix this problem once and for all using a general taskqueue to call
if_ioctl() method in all cases when if_addmulti() is called in a
non sleeping context.  Note that nobody cares about returned value.

Reviewed by:	hselasky, kib
Differential Revision:	  https://reviews.freebsd.org/D22154
This commit is contained in:
Gleb Smirnoff 2019-10-29 17:36:06 +00:00
parent 5757b59f3e
commit 0839aa5c04
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=354149
2 changed files with 21 additions and 1 deletions
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21
sys/net/if.c
View File

@ -271,6 +271,7 @@ static int if_getgroupmembers(struct ifgroupreq *);
static void if_delgroups(struct ifnet *);
static void if_attach_internal(struct ifnet *, int, struct if_clone *);
static int if_detach_internal(struct ifnet *, int, struct if_clone **);
static void if_siocaddmulti(void *, int);
#ifdef VIMAGE
static void if_vmove(struct ifnet *, struct vnet *);
#endif
@ -556,6 +557,7 @@ if_alloc_domain(u_char type, int numa_domain)
IF_ADDR_LOCK_INIT(ifp);
TASK_INIT(&ifp->if_linktask, 0, do_link_state_change, ifp);
TASK_INIT(&ifp->if_addmultitask, 0, if_siocaddmulti, ifp);
ifp->if_afdata_initialized = 0;
IF_AFDATA_LOCK_INIT(ifp);
CK_STAILQ_INIT(&ifp->if_addrhead);
@ -1131,6 +1133,7 @@ if_detach_internal(struct ifnet *ifp, int vmove, struct if_clone **ifcp)
if_delgroups(ifp);
taskqueue_drain(taskqueue_swi, &ifp->if_linktask);
taskqueue_drain(taskqueue_swi, &ifp->if_addmultitask);
/*
* Check if this is a cloned interface or not. Must do even if
@ -3538,7 +3541,10 @@ if_addmulti(struct ifnet *ifp, struct sockaddr *sa,
* interface to let them know about it.
*/
if (ifp->if_ioctl != NULL) {
(void) (*ifp->if_ioctl)(ifp, SIOCADDMULTI, 0);
if (THREAD_CAN_SLEEP())
(void )(*ifp->if_ioctl)(ifp, SIOCADDMULTI, 0);
else
taskqueue_enqueue(taskqueue_swi, &ifp->if_addmultitask);
}
if ((llsa != NULL) && (llsa != (struct sockaddr *)&sdl))
@ -3555,6 +3561,19 @@ if_addmulti(struct ifnet *ifp, struct sockaddr *sa,
return (error);
}
static void
if_siocaddmulti(void *arg, int pending)
{
struct ifnet *ifp;
ifp = arg;
#ifdef DIAGNOSTIC
if (pending > 1)
if_printf(ifp, "%d SIOCADDMULTI coalesced\n", pending);
#endif
(void )(*ifp->if_ioctl)(ifp, SIOCADDMULTI, 0);
}
/*
* Delete a multicast group membership by network-layer group address.
*

1
sys/net/if_var.h
View File

@ -317,6 +317,7 @@ struct ifnet {
struct ifaltq if_snd; /* output queue (includes altq) */
struct task if_linktask; /* task for link change events */
struct task if_addmultitask; /* task for SIOCADDMULTI */
/* Addresses of different protocol families assigned to this if. */
struct mtx if_addr_lock; /* lock to protect address lists */