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
- the userland call is now made to PM only, and PM relays the call to
other servers as appropriate; this is an ABI change that will
ultimately allow us to add proper support for wait3() and the like;
for the moment there is backward compatibility;
- the getrusage-specific kernel subcall has been removed, as it
provided only redundant functionality, and did not provide the means
to be extended correctly in the future - namely, allowing the kernel
to return different values depending on whether resource usage of
the caller (self) or its children was requested;
- VM is now told whether resource usage of the caller (self) or its
children is requested, and it refrains from filling in wrong values
for information it does not have;
- VM now uses the correct unit for the ru_maxrss values;
- VFS is cut out of the loop entirely, since it does not provide any
values at the moment; a comment explains how it should be readded.
Change-Id: I27b0f488437dec3d8e784721c67b03f2f853120f
Due to changed VM internals, more elaborate preparation is required
before a live update with multiple components including VM can take
place. This patch adds the essential preparation infrastructure to
VM and adapts RS to make use of it. As a side effect, it is no
longer necessary to supply RS as the last component (if at all)
during the set-up of a multicomponent live update operation.
Change-Id: If069fd3f93f96f9d5433998e4615f861465ef448
The entire infrastructure relied on an ACK feature, and as such, it
has been broken for years now, with no easy way to repair it.
Change-Id: I783c2a21276967af115a642199f31fef0f14a572
