There is a big mix of LockRefPtrs all over the Networking subsystem, as
well as lots of room for improvements with our locking patterns, which
this commit will not pursue, but will give a good start for such work.
To deal with this situation, we change the following things:
- Creating instances of NetworkAdapter should always yield a non-locking
NonnullRefPtr. Acquiring an instance from the NetworkingManagement
should give a simple RefPtr,as giving LockRefPtr does not really
protect from concurrency problems in such case.
- Since NetworkingManagement works with normal RefPtrs we should
protect all instances of RefPtr<NetworkAdapter> with SpinlockProtected
to ensure references are gone unexpectedly.
- Protect the so_error class member with a proper spinlock. This happens
to be important because the clear_so_error() method lacked any proper
locking measures. It also helps preventing a possible TOCTOU when we
might do a more fine-grained locking in the Socket code, so this could
be definitely a start for this.
- Change unnecessary LockRefPtr<PacketWithTimestamp> in the structure
of OutgoingPacket to a simple RefPtr<PacketWithTimestamp> as the whole
list should be MutexProtected.
This step would ideally not have been necessary (increases amount of
refactoring and templates necessary, which in turn increases build
times), but it gives us a couple of nice properties:
- SpinlockProtected inside Singleton (a very common combination) can now
obtain any lock rank just via the template parameter. It was not
previously possible to do this with SingletonInstanceCreator magic.
- SpinlockProtected's lock rank is now mandatory; this is the majority
of cases and allows us to see where we're still missing proper ranks.
- The type already informs us what lock rank a lock has, which aids code
readability and (possibly, if gdb cooperates) lock mismatch debugging.
- The rank of a lock can no longer be dynamic, which is not something we
wanted in the first place (or made use of). Locks randomly changing
their rank sounds like a disaster waiting to happen.
- In some places, we might be able to statically check that locks are
taken in the right order (with the right lock rank checking
implementation) as rank information is fully statically known.
This refactoring even more exposes the fact that Mutex has no lock rank
capabilites, which is not fixed here.
When scanning for network adapters, we give each driver a chance to
claim the PCI device and whoever claims it first gets to keep it.
Before this patch, the driver API returned a LockRefPtr<AdapterType>,
which made it impossible to propagate errors that occurred during
detection and/or initialization.
This patch changes the API so that errors can bubble all the way out
the PCI enumeration in NetworkingManagement::initialize() where we
perform all the network adapter auto-detection on boot.
When we eventually start to support hot-plugging network adapter in the
future, it will be even more important to propagate errors instead of
swallowing them.
Importantly, before this patch, some errors were "handled" by panicking
the kernel. This is no longer the case.
7 FIXMEs were killed in the making of this commit. :^)
Until now, our kernel has reimplemented a number of AK classes to
provide automatic internal locking:
- RefPtr
- NonnullRefPtr
- WeakPtr
- Weakable
This patch renames the Kernel classes so that they can coexist with
the original AK classes:
- RefPtr => LockRefPtr
- NonnullRefPtr => NonnullLockRefPtr
- WeakPtr => LockWeakPtr
- Weakable => LockWeakable
The goal here is to eventually get rid of the Lock* classes in favor of
using external locking.
All users which relied on the default constructor use a None lock rank
for now. This will make it easier to in the future remove LockRank and
actually annotate the ranks by searching for None.
This was a premature optimization from the early days of SerenityOS.
The eternal heap was a simple bump pointer allocator over a static
byte array. My original idea was to avoid heap fragmentation and improve
data locality, but both ideas were rooted in cargo culting, not data.
We would reserve 4 MiB at boot and only ended up using ~256 KiB, wasting
the rest.
This patch replaces all kmalloc_eternal() usage by regular kmalloc().
We now use AK::Error and AK::ErrorOr<T> in both kernel and userspace!
This was a slightly tedious refactoring that took a long time, so it's
not unlikely that some bugs crept in.
Nevertheless, it does pass basic functionality testing, and it's just
real nice to finally see the same pattern in all contexts. :^)
This change allows the Kernel to actually construct other interfaces
besides the E1000 type.
This solves a breakage that was introduced recently because of move
semantics.
A couple of points on this patch:
1. In current situation, we can waste time to create a KString and throw
it for nothing. This patch ensures we only create it near construction
point so we know we actually need it.
2. It's very likely to assume that non-x86 machines will expose network
device with a device tree (or with ACPI). The raspberry pi machine is a
good example of that. Therefore, each driver should explicitly ask the
correct interface name generation method, and this patch simplifies this
pattern greatly, especially in a case where the same network device can
appear as a PCI device or as device in another bus type on the same
platform target. For example, the (in)famous ne2000 device can be used
either as a PCI device or as an ISA device, depending on the model.
3. In my opinion, it seems much more readable to construct the name near
calling point of the object constructor than to just pass it with move
semantics.
Instead of initializing network adapters in init.cpp, let's move that
logic into a separate class to handle this.
Also, it seems like a good idea to shift responsiblity on enumeration
of network adapters after the boot process, so this singleton will take
care of finding the appropriate network adapter when asked to with an
IPv4 address or interface name.
With this change being merged, we simplify the creation logic of
NetworkAdapter derived classes, so we enumerate the PCI bus only once,
searching for driver candidates when doing so, and we let each driver
to test if it is resposible for the specified PCI device.
