On 1/01/2020 5:58 am, Alexander Motin wrote:
Author: mav
Date: Tue Dec 31 18:58:29 2019
New Revision: 356240
URL: https://svnweb.freebsd.org/changeset/base/356240
Log:
Relax locking of carp_forus().
This fixes deadlock between CARP and bridge. Bridge calls this function
taking CARP lock while holding bridge lock. Same time CARP tries to send
its announcements via the bridge while holding CARP lock.
Use of CARP_LOCK() here does not solve anything, since sc_addr is constant
while race on sc_state is harmless and use of the lock does not close it.
Reviewed by: glebius
MFC after: 2 weeks
Sponsored by: iXsystems, Inc.
Modified:
head/sys/netinet/ip_carp.c
Modified: head/sys/netinet/ip_carp.c
==============================================================================
--- head/sys/netinet/ip_carp.c Tue Dec 31 18:28:25 2019 (r356239)
+++ head/sys/netinet/ip_carp.c Tue Dec 31 18:58:29 2019 (r356240)
@@ -1230,14 +1230,15 @@ carp_forus(struct ifnet *ifp, u_char *dhost)
CIF_LOCK(ifp->if_carp);
IFNET_FOREACH_CARP(ifp, sc) {
- CARP_LOCK(sc);
+ /*
+ * CARP_LOCK() is not here, since would protect nothing, but
+ * cause deadlock with if_bridge, calling this under its lock.
+ */
if (sc->sc_state == MASTER && !bcmp(dhost, LLADDR(&sc->sc_addr),
ETHER_ADDR_LEN)) {
- CARP_UNLOCK(sc);
CIF_UNLOCK(ifp->if_carp);
return (1);
}
- CARP_UNLOCK(sc);
}
CIF_UNLOCK(ifp->if_carp);
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Hi Alexander,
Is this a only-head-impacted fix, or does the issue impact stable/12,11
too, warranting MFC ?
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