Now that there are services other than PM and VFS that implement
userland system calls directly, these services may need to know about
events related to user processes. In particular, signal delivery may
have to interrupt blocking system calls, and certain cleanup tasks may
have to be performed after a user process exits.
This patch aims to implement a generic, lasting solution for this
problem, by allowing services to subscribe to "signal delivered"
and/or "process exit" events from PM. PM publishes such events by
sending messages to its subscribed services, which must then reply an
acknowledgment message.
For now, only the two aforementioned events are implemented, and only
the IPC service makes use of the process event facility.
The new process event publish/subscribe system replaces the previous
VM notify-sig/watch-exit/query-exit system, which was unsound: 1) it
allowed subscription to events from individual processes, and suffered
from fundamental race conditions as a result; 2) it relied on "not too
many" processes making use of the IPC server functionality in order to
avoid loss of notifications. In addition, it had the "ipc" process
name hardcoded, did not distinguish between signal delivery and exits,
and added a roundtrip to VM for all events from all processes.
Change-Id: I75ebad4bc54e646c6433f473294cb4003b2c3430
- About 80% of PM's process table consisted of per-signal sigaction
structures. This is information not used by the MIB service, and
can safely be stored outside the main process table.
- The MIB service does not need most of the VFS process table, so VFS
now generates a "light" version of its table upon request, with just
the fields used by the MIB service.
The result is a size reduction of the MIB service of about 700KB.
Change-Id: I79fe7239361fbfb45286af8e86a10aed4c2d2be7
This patch adds support for the wait4 system call, and with that the
wait3 call as well. The implementation is absolutely minimal: only
user and system times of the exited child are returned (with all other
rusage fields left zero), and there is no support for tracers. Still,
this should cover the main use cases of wait4.
Change-Id: I7a04589a8423a23990ab39aa38e85d535556743a
POSIX states that times() and getrusage() should only return child
user and system times of terminated children for which wait*() has
returned their PIDs.
Change-Id: I38e19ad71543a3b91e944bef8e4e1bd903de51bf
Changes provoked by debugging / making 'PM: INIT died' error debuggable.
This was caused (in one instance) by a missing /dev/console (and everything
else) on the boot time ramdisk.
. sanity-check against this case by checking for console
. PM: print init stacktrace and exit status when init dies
. eliminate some explicitly invoked ${MAKE}s and a rm -rf in
Makefiles, causing race conditions; use explicit ordering (.WAIT)
instead, moving some of the burden of dependencies of partial builds
to the user. On the plus side, generate ramdisk just once.
. make mkfs.mfs fail as soon as it sees an error missing file in
the proto file. - except for EACCES on minix native for the mfs
test. also fix some fmt warnings.
. init: include debug info in executable
Change-Id: I8eea4986a4f64ecaf223aff5da321d8b4f4a3fa4
