Spotted by Christian Zander.

already being unhashed on entry.

as we delete the entry, we can only poison the back pointer, not the
traversal pointer (rcu traversal only ever walks forward).

Make __d_drop() take this into account.

into home.transmeta.com:/home/torvalds/v2.5/linux

drivers/char/pty.c converted to dynamic allocation

drivers/char/rio/rio_linux.c converted to dynamic allocation

drivers/char/epca.c converted to dynamic allocation

arch/v850/kernel/{memcons,simcons}.c converted to dynamic allocation

drivers/char/vt.c converted to dynamic allocation

arch/um/drivers/* converted to dynamic allocation

arch/cris/drivers/serial.c converted to dynamic allocation

arch/alpha/kernel/srmcons.c converted to dynamic allocation

drivers/s390/char/con3215.c converted to dynamic allocation

drivers/s390/char/sclp_tty.c converted to dynamic allocation

drivers/s390/char/tubtty.c converted to dynamic allocation

drivers/s390/net/ctctty.c converted to dynamic allocation

drivers/isdn/capi/capi.c converted to dynamic allocation

arch/mips/baget/vacserial.c converted to dynamic allocation

arch/ppc/8xx_io/uart.c converted to dynamic allocation

arch/ppc/8260_io/uart.c converted to dynamic allocation

drivers/usb/serial/usb-serial.c converted to dynamic allocation

drivers/char/ip2main.c converted to dynamic allocation

arch/mips/au1000/common/serial.c converted to dynamic allocation

arch/ia64/hp/sim/simserial.c converted to dynamic allocation

arch/ppc/4xx_io/serial_sicc.c converted to dynamic allocation

drivers/usb/class/cdc-acm.c converted to dynamic allocation

drivers/char/esp.c converted to dynamic allocation

drivers/usb/class/bluetty.c converted to dynamic allocation

drivers/isdn/i4l/isdn_tty.c converted to dynamic allocation

drivers/char/hvc_console.c converted to dynamic allocation

drivers/char/pcmcia/synclink_cs.c converted to dynamic allocation

drivers/char/synclinkmp.c converted to dynamic allocation

drivers/char/synclink.c converted to dynamic allocation

drivers/char/mxser.c converted to dynamic allocation

drivers/char/moxa.c converted to dynamic allocation

drivers/char/pcxx.c converted to dynamic allocation

drivers/char/riscom8.c converted to dynamic allocation

drivers/char/rocket.c converted to dynamic allocation

drivers/char/isicom.c converted to dynamic allocation

drivers/char/cyclades.c converted to dynamic allocation