Relax per-ifnet cif_vrs list double locking in carp(4).
In all cases where cif_vrs list is modified, two locks are held: per-ifnet CIF_LOCK and global carp_sx. It means to read that list only one of them is enough to be held, so we can skip CIF_LOCK when we already have carp_sx. This fixes kernel panic, caused by attempts of copyout() to sleep while holding non-sleepable CIF_LOCK mutex. Discussed with: glebius MFC after: 2 weeks Sponsored by: iXsystems, Inc.
This commit is contained in:
parent
4074d642d2
commit
81098a018e
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=324752
@ -175,8 +175,8 @@ static int proto_reg[] = {-1, -1};
|
||||
* Each softc has a lock sc_mtx. It is used to synchronise carp_input_c(),
|
||||
* callout-driven events and ioctl()s.
|
||||
*
|
||||
* To traverse the list of softcs on an ifnet we use CIF_LOCK(), to
|
||||
* traverse the global list we use the mutex carp_mtx.
|
||||
* To traverse the list of softcs on an ifnet we use CIF_LOCK() or carp_sx.
|
||||
* To traverse the global list we use the mutex carp_mtx.
|
||||
*
|
||||
* Known issues with locking:
|
||||
*
|
||||
@ -286,7 +286,8 @@ SYSCTL_VNET_PCPUSTAT(_net_inet_carp, OID_AUTO, stats, struct carpstats,
|
||||
++_i)
|
||||
|
||||
#define IFNET_FOREACH_CARP(ifp, sc) \
|
||||
CIF_LOCK_ASSERT(ifp->if_carp); \
|
||||
KASSERT(mtx_owned(&ifp->if_carp->cif_mtx) || \
|
||||
sx_xlocked(&carp_sx), ("cif_vrs not locked")); \
|
||||
TAILQ_FOREACH((sc), &(ifp)->if_carp->cif_vrs, sc_list)
|
||||
|
||||
#define DEMOTE_ADVSKEW(sc) \
|
||||
@ -1562,6 +1563,8 @@ carp_alloc(struct ifnet *ifp)
|
||||
struct carp_softc *sc;
|
||||
struct carp_if *cif;
|
||||
|
||||
sx_assert(&carp_sx, SA_XLOCKED);
|
||||
|
||||
if ((cif = ifp->if_carp) == NULL)
|
||||
cif = carp_alloc_if(ifp);
|
||||
|
||||
@ -1751,11 +1754,9 @@ carp_ioctl(struct ifreq *ifr, u_long cmd, struct thread *td)
|
||||
}
|
||||
|
||||
if (ifp->if_carp) {
|
||||
CIF_LOCK(ifp->if_carp);
|
||||
IFNET_FOREACH_CARP(ifp, sc)
|
||||
if (sc->sc_vhid == carpr.carpr_vhid)
|
||||
break;
|
||||
CIF_UNLOCK(ifp->if_carp);
|
||||
}
|
||||
if (sc == NULL) {
|
||||
sc = carp_alloc(ifp);
|
||||
@ -1826,11 +1827,9 @@ carp_ioctl(struct ifreq *ifr, u_long cmd, struct thread *td)
|
||||
|
||||
priveleged = (priv_check(td, PRIV_NETINET_CARP) == 0);
|
||||
if (carpr.carpr_vhid != 0) {
|
||||
CIF_LOCK(ifp->if_carp);
|
||||
IFNET_FOREACH_CARP(ifp, sc)
|
||||
if (sc->sc_vhid == carpr.carpr_vhid)
|
||||
break;
|
||||
CIF_UNLOCK(ifp->if_carp);
|
||||
if (sc == NULL) {
|
||||
error = ENOENT;
|
||||
break;
|
||||
@ -1841,7 +1840,6 @@ carp_ioctl(struct ifreq *ifr, u_long cmd, struct thread *td)
|
||||
int i, count;
|
||||
|
||||
count = 0;
|
||||
CIF_LOCK(ifp->if_carp);
|
||||
IFNET_FOREACH_CARP(ifp, sc)
|
||||
count++;
|
||||
|
||||
@ -1863,7 +1861,6 @@ carp_ioctl(struct ifreq *ifr, u_long cmd, struct thread *td)
|
||||
}
|
||||
i++;
|
||||
}
|
||||
CIF_UNLOCK(ifp->if_carp);
|
||||
}
|
||||
break;
|
||||
}
|
||||
@ -1918,11 +1915,9 @@ carp_attach(struct ifaddr *ifa, int vhid)
|
||||
return (ENOPROTOOPT);
|
||||
}
|
||||
|
||||
CIF_LOCK(cif);
|
||||
IFNET_FOREACH_CARP(ifp, sc)
|
||||
if (sc->sc_vhid == vhid)
|
||||
break;
|
||||
CIF_UNLOCK(cif);
|
||||
if (sc == NULL) {
|
||||
sx_xunlock(&carp_sx);
|
||||
return (ENOENT);
|
||||
|
Loading…
Reference in New Issue
Block a user