Previously, VFS would use various subsets of a number of fproc
structure fields to store state when the process is blocked
(suspended) for various reasons. As a result, there was a fair
amount of abuse of fields, hidden state, and confusion as to
which fields were used with which suspension states.
Instead, the suspension state is now split into per-state
structures, which are then stored in a union. Each of the union's
structures should be accessed only right before, during, and right
after the fp_blocked_on field is set to the corresponding blocking
type. As a result, it is now very clear which fields are in use
at which times, and we even save a bit of memory as a side effect.
Change-Id: I5c24e353b6cb0c32eb41c70f89c5cfb23f6c93df
With this patch, the IPC service is changed to use the new RMIB
facility to register and handle the "kern.ipc" sysctl subtree itself.
The subtree was previously handled by the MIB service directly. This
change improves locality of handling: especially the
kern.ipc.sysvipc_info node has some peculiarities specific to the IPC
service and is therefore better handled there. Also, since the IPC
service is essentially optional to the system, this rearrangement
yields a cleaner situation when the IPC service is not running: in
that case, the MIB service will expose a few basic kern.ipc nodes
indicating that no SysV IPC facilities are present. Those nodes will
be overridden through RMIB when the IPC service is running.
It should be easier to add the remaining (from NetBSD) kern.ipc nodes
as well now.
Test88 is extended with a new subtest that verifies that sysctl-based
information retrieval for semaphore sets works as expected.
Change-Id: I6b7730e85305b64cfd8418c0cc56bde64b22c584
Most of the nodes in the general sysctl tree will be managed directly
by the MIB service, which obtains the necessary information as needed.
However, in certain cases, it makes more sense to let another service
manage a part of the sysctl tree itself, in order to avoid replicating
part of that other service in the MIB service. This patch adds the
basic support for such delegation: remote services may now register
their own subtrees within the full sysctl tree with the MIB service,
which will then forward any sysctl(2) requests on such subtrees to the
remote services.
The system works much like mounting a file system, but in addition to
support for shadowing an existing node, the MIB service also supports
creating temporary mount point nodes. Each have their own use cases.
A remote "kern.ipc" would use the former, because even when such a
subtree were not mounted, userland would still expect some of its
children to exist and return default values. A remote "net.inet"
would use the latter, as there is no reason to precreate nodes for all
possible supported networking protocols in the MIB "net" subtree.
A standard remote MIB (RMIB) implementation is provided for services
that wish to make use of this functionality. It is essentially a
simplified and somewhat more lightweight version of the MIB service's
internals, and works more or less the same from a programmer's point
of view. The most important difference is the "rmib" prefix instead
of the "mib" prefix. Documentation will hopefully follow later.
Overall, the RMIB functionality should not be used lightly, for
several reasons. First, despite being more lightweight than the MIB
service, the RMIB module still adds substantially to the code
footprint of the containing service. Second, the RMIB protocol not
only adds extra IPC for sysctl(2), but has also not been optimized for
performance in other ways. Third, and most importantly, the RMIB
implementation also several limitations. The main limitation is that
remote MIB subtrees must be fully static. Not only may the user not
create or destroy nodes, the service itself may not either, as this
would clash with the simplified remote node versioning system and
the cached subtree root node child counts. Other limitations exist,
such as the fact that the root of a remote subtree may only be a
node-type node, and a stricter limit on the highest node identifier
of any child in this subtree root (currently 4095).
The current implementation was born out of necessity, and therefore
it leaves several improvements to future work. Most importantly,
support for exit and crash notification is missing, primarily in the
MIB service. This means that remote subtrees may not be cleaned up
immediately, but instead only when the MIB service attempts to talk
to the dead remote service. In addition, if the MIB service itself
crashes, re-registration of remote subtrees is currently left up to
the individual RMIB users. Finally, the MIB service uses synchronous
(sendrec-based) calls to the remote services, which while convenient
may cause cascading service hangs. The underlying protocol is ready
for conversion to an asynchronous implementation already, though.
A new test set, testrmib.sh, tests the basic RMIB functionality. To
this end it uses a test service, rmibtest, and also reuses part of
the existing test87 MIB service test.
Change-Id: I3378fe04f2e090ab231705bde7e13d6289a9183e
This patch aims to synchronize the basic process user and group ID
management, as well as the set[ug]id(2) and sete[ug]id(2) behavior,
with NetBSD. As it turns out, the main issue was missing support for
saved user and group IDs. This support is now added.
Since NetBSD's userland, which we are importing, may rely on NetBSD
specifics when it comes to security, we choose not to deviate from
NetBSD's behavior in any way here. A new test, test89, verifies the
correct behavior - it has been confirmed to pass on NetBSD as is.
Change-Id: I023935546d97ed01ffd8090f7793d336cceb0f4a
The kernel.ipc.sysvipc_info node is the gateway from NetBSD ipcs(1)
and ipcrm(1) to the IPC server, and thus necessary for a clean
import of these two utilities. The MIB service implementation uses
the preexisting (Linux-specific) information calls on the IPC server
to obtain the information.
Change-Id: I85d1e193162d6b689f114764254dd7f314d2cfa0
- 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
Instead of pulling in process tables itself, ProcFS now queries the
MIB service for process information. This reduces ProcFS's memory
usage by about 1MB. The change does have two negative consequences.
First, getting all the original /proc/<pid>/psinfo fields filled in
would take a lot of extra effort. Since the only program that uses
those files at all is mtop(1), we reformat psinfo to expose only the
information used by mtop(1). This means that with this patch, older
copies of MINIX3 ps and top will cease to work.
Second, since both MIB and ProcFS update their own view of the
process list only once per clock tick, ProcFS' view may now be
outdated by up to two clock ticks. This is unlikely to pose a
problem in practice.
Change-Id: Iaa6b60450c8fb52d092962394d33d08bd638bc01
The new MIB service implements the sysctl(2) system call which, as
we adopt more NetBSD code, is an increasingly important part of the
operating system API. The system call is implemented in the new
service rather than as part of an existing service, because it will
eventually call into many other services in order to gather data,
similar to ProcFS. Since the sysctl(2) functionality is used even
by init(8), the MIB service is added to the boot image.
MIB stands for Management Information Base, and the MIB service
should be seen as a knowledge base of management information.
The MIB service implementation of the sysctl(2) interface is fairly
complete; it incorporates support for both static and dynamic nodes
and imitates many NetBSD-specific quirks expected by userland. The
patch also adds trace(1) support for the new system call, and adds
a new test, test87, which tests the fundamental operation of the
MIB service rather thoroughly.
Change-Id: I4766b410b25e94e9cd4affb72244112c2910ff67
