LINUX 5.3.0: Use send_sig instead of force_sig
Linux 5.3.0 commit
3cf5d076fb4d48979f382bc9452765bf8b79e740 "signal
Remove task parameter from force_sig" (part of siginfo-linus branch)
changes the parameters for the Linux kernel function force_sig. See LKML
thread starting at https://lkml.org/lkml/2019/5/22/1351
According to the LKML discussion and the above commit message force_sig
is only safe to deliver a synchronous signal to the current task. To
send a signal to another task, we're supposed to use send_sig instead,
which has been available since at least linux 2.6.12-rc12.
Currently, rx_knet calls force_sig to kill the rxk_ListenerTask. With
the Linux 5.3.0 kernel, this module fails to compile due to the above
noted changes.
Replace the force_sig call with send_sig. In order to use send_sig, the
rxk_listener thread must allow SIGKILL and during shutdown (umount)
SIGKILL must be unblocked for the rxk_listener thread.
Note that SIGKILL is initially blocked on rxk_listener and is only
unblocked when shutting down the thread. Having the signal blocked is
sufficient to prevent unwanted signals from reaching the rxk_listener
thread during normal operation.
Change-Id: I0c31d66f4ecd887ff9253ba506565592010e8bcb
Reviewed-on: https://gerrit.openafs.org/13753
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>