CVSROOT: /cvs
Module name: src
Changes by: d...@cvs.openbsd.org 2015/12/08 20:22:39
Modified files:
sys/dev/pci : if_myx.c
sys/net : if.c if_var.h ifq.c ifq.h
Log message:
rework the if_start mpsafe serialisation so it can serialise arbitrary work
work is represented by struct task.
the start routine is now wrapped by a task which is serialised by the
infrastructure. if_start_barrier has been renamed to ifq_barrier and
is now implemented as a task that gets serialised with the start
routine.
this also adds an ifq_restart() function. it serialises a call to
ifq_clr_oactive and calls the start routine again. it exists to
avoid a race that kettenis@ identified in between when a start
routine discovers theres no space left on a ring, and when it calls
ifq_set_oactive. if the txeof side of the driver empties the ring
and calls ifq_clr_oactive in between the above calls in start, the
queue will be marked oactive and the stack will never call the start
routine again.
by serialising the ifq_set_oactive call in the start routine and
ifq_clr_oactive calls we avoid that race.
tested on various nics
ok mpi@
