PR/54189 CVS commit: src/sys

["Ryota Ozaki" <ozaki-r%netbsd.org@localhost>]

The following reply was made to PR kern/54189; it has been noted by GNATS.

From: "Ryota Ozaki" <ozaki-r%netbsd.org@localhost>
To: gnats-bugs%gnats.NetBSD.org@localhost
Cc: 
Subject: PR/54189 CVS commit: src/sys
Date: Wed, 15 May 2019 02:56:48 +0000

 Module Name:	src
 Committed By:	ozaki-r
 Date:		Wed May 15 02:56:48 UTC 2019
 
 Modified Files:
 	src/sys/dev/ic: dwc_gmac.c
 	src/sys/dev/pci: if_wm.c
 	src/sys/dev/pci/ixgbe: ixgbe.c
 	src/sys/net: if.c if_ether.h if_ethersubr.c
 
 Log Message:
 Store IFF_ALLMULTI in ec_flags instead of if_flags to avoid data races
 
 IFF_ALLMULTI is set/unset to if_flags via if_mcast_op.  To avoid data races on
 if_flags, IFNET_LOCK was added for if_mcast_op.  Unfortunately it produces
 a deadlock so we want to remove added IFNET_LOCK by avoiding the data races by
 another approach.
 
 This fix introduces ec_flags to struct ethercom and stores IFF_ALLMULTI to it.
 ec_flags is protected by ETHER_LOCK and thus IFNET_LOCK is no longer necessary
 for if_mcast_op.  Note that the fix is applied only to MP-safe drivers that
 the data races matter.
 
 In the kernel, IFF_ALLMULTI is set by a driver and used by the driver itself.
 So changing the storing place doesn't break anything.  One exception is
 ioctl(SIOCGIFFLAGS); we have to include IFF_ALLMULTI in a result if needed to
 export the flag as well as before.
 
 A upcoming commit will remove IFNET_LOCK.
 
 PR kern/54189
 
 
 To generate a diff of this commit:
 cvs rdiff -u -r1.59 -r1.60 src/sys/dev/ic/dwc_gmac.c
 cvs rdiff -u -r1.635 -r1.636 src/sys/dev/pci/if_wm.c
 cvs rdiff -u -r1.182 -r1.183 src/sys/dev/pci/ixgbe/ixgbe.c
 cvs rdiff -u -r1.451 -r1.452 src/sys/net/if.c
 cvs rdiff -u -r1.77 -r1.78 src/sys/net/if_ether.h
 cvs rdiff -u -r1.273 -r1.274 src/sys/net/if_ethersubr.c
 
 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.