When a condvar's timeout and wakeup race, we wait for the concurrent
wakeup to complete, so it won't crash. We did this wr.wait() with
the condvar's internal mutex (m) locked, which was fine when this code
was written; But now that we have wait morphing, wr.wait() waits not
just for the wakeup to complete, but also for the user_mutex to become
available. With m locked and us waiting for user_mutex, we're now in
deadlock territory - because a common idiom of using a condvar is to
do the locks in opposite order: lock user_mutex first and then use the
condvar, which locks m.

I can't think of an easy way to actually demonstrate this deadlock,
short of having a locked condvar_wait timeout racing with condvar_wake_one
racing and then an additional locked condvar operation coming in
concurrently, but I don't have a test case demonstrating this.
I am hoping it will fix the lockups that Pekka is seeing in his
Cassandra tests (which are the reason I looked for possible condvar
deadlocks in the first place).

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Tested-by: Pekka Enberg <penberg@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

The problem with sleep, is that we can initialize early threads before the
cpu itself is initialized. If we note what goes on in init_on_cpu, it should
become clear:

void cpu::init_on_cpu()
{
    arch.init_on_cpu();
    clock_event->setup_on_cpu();
}

When we finally initialize the clock_event, it can get lost if we already have
pending timers of any kind - which we may, if we have early threads being
start()ed before that. I have played with many potential solutions, but in the
end, I think the most sensible thing to do is to delay initialization of early
threads to the point when we are first idle. That is the best way to guarantee
that everything will be properly initialized and running.

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

Fixed a couple of spelling mistakes in README.md

Signed-off-by: Omer Karadagli <ufokaradagli@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

To prevent leaks when a file is close()d without an EPOLL_CTL_DEL,
record epoll registrations in the file structure and remove them
when the file is destroyed.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Avoid possible blocking.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Make sure to wait until the running thread count drops to zero
before destroying things.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Since it's initialized with the constructor, the mutex is already initialized.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

use file::operator delete to ensure it is reclaimed via rcu,
and let the rest of the cleanup happen via the destructor.

This allows us to add other members to file, and let the standard
construction/destruction sequence take place.

Note the constructor is already used (falloc_noinstall()).

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Holding filerefs causes close() to be delayed indefinitly in case
the user "forgets" to EPOLL_CTL_DEL the file before close().

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Previously, _Unwind_Resume wasn't available, so functions that handled an
exception implicitly (by running a few destructors) crashed.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Commit c9e61d4a ("build: link libstdc++, libgcc_s only once") threw
away libgcc_s.so since we already link with libgcc.a and libgcc_eh.a, which
provide the same symbols, and since having the same symbols in multiple
objects violates certain C++ rules.

However, libgcc_eh.a provides certain symbols only as local symbols, which
means they aren't available to the payload.  This manifests itself in errors
such as failing to find _Unwind_Resume if an exception is thrown.

(This is likely due to the requirement that mulitple objects linked with
libgcc_eh.a work together, which also brings some confidence that the ODR
violations of having two versions of the library won't bite us).

Fix the problem by adding libgcc_s.so to the filesystem and allowing
the payload to link to it.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

prio.hh defines various initialization priorities. The actual numbers
don't matter, just the order between them. But when we add too many
priorities between existing ones, we may hit a need to renumber. This
is plain ugly, and reminds me of Basic programming ;-)

So this patch switches to an enum (enum class, actually).
We now just have a list of priority names in order, with no numbers.

It would have been straightforward, if it weren't for a bug in GCC
(see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59211

) where the
"init_priority" attribute doesn't accept the enum (while the "constructor"
attribute does). Luckily, a simple workaround - explicitly casting to
int - works.

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

The test creates and destroys threads, each of which creates a random number
of connections, each transferring a random number of bytes to an echo server.

This is used to stress the tcp/ip stack.

The test is portable, and builds on the host with the command

  g++ -O2  -g3 -pthread -std=gnu++11 -lboost_program_options -lboost_system tests/tst-tcp.cc

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Instead of using file descriptors and poll(), use do_poll().  This allows
us to get rid of user supplied fds early, which is important as fd lifetime
is decoupled from epoll lifetime.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

With epoll(), the lifetime of an ongoing poll may be longer than the
lifetime of a file descriptor; if an fd is close()d then we expect it
to be silently removed from the epoll.

With the current implementation of epoll(), which just calls poll(), this is
impossible to do correctly since poll() is implemented in terms of file
descriptor.

Add an intermedite do_poll() that works on file pointers. This allows a
refactored epoll() to convert file descriptors to file pointers just once,
and then a close()d and re-open()ed descriptor can be added without a problem.

As a side effect, a lot of atomic operations (fget() and fdrop()) are saved.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Provide a better error message instead of simply printing the error
codes.

Before:

  failed to create /dev, error = 17

After:

  failed to create /dev, error = File exists

Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

This patch adds the unsafe-cache option to run.py and changes mkzfs.py
to always call run.py with this option enabled.
Thus, we're doing this change just for the build run (Suggested by Nadav Har'El).
The main goal is to boost the time it takes to complete the entire process.

Reviewed-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

TLB flushes cannot happen early, because we will try to send IPIs around before
they are ready to go. Now, the funny thing is *why* that happen:

We test for the size of the cpu vector to be 1. But before the cpus are
initialized, that vector is empty. Because there is a limit on how soon we can
initialize a cpu(), let's change the test to also acount for an empty vector.
It should be obvious and clear that when we have an empty vector, only one cpu
is present.

I have triggered this in the context of my last patchset for threads. My test
script was set to -c1 (sorry about that), and as soon as I tested it with SMP
it exploded here.

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

We may have threads that were initialized and started very early, before
sched::init() took place. We can easily identify such threads: they are all
threads that are in the thread list so far with the exception of the main
thread.

For those, we finish their initialization so they are now in a safe state.
Also, some of them may have been started already. Since we cannot really start
anything before the main thread, they were put in as special state called
"prestarted". Every thread found in this state is started at this moment.

Note how this code needs to run in the main thread itself, since we depend on
initialization that will only happen inside switch_to_first to properly
function those procedures.

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Reviewed-by: Pekka Enberg <penberg@cloudius-systems.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

It may be that a thread that is initialized early is also started early. We need to
somehow mark that thread as already started, so we can start it for real later when
the scheduler is ready to go. We will do this by adding an extra state, prestarted.

Later on, we will take action to start those threads properly.

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Reviewed-by: Pekka Enberg <penberg@cloudius-systems.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

Threads that are created very early will see this field with a NULL address. We
should test against it before dereferencing. If we found current not to be
available, we skip some steps or use default values.

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Reviewed-by: Pekka Enberg <penberg@cloudius-systems.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

Since the thread list does not depend on nothing but the memory allocator,
allocate it as early as we can.

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Reviewed-by: Pekka Enberg <penberg@cloudius-systems.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

Currently, when we try to run an invalid shared object (e.g, run.py -e aaa)
loader.cc calls abort(). This patch changes it to use osv::poweroff().

This is useful, for example, to measure how much time our boot/poweroff
cycle takes, without running any payload, by doing

	time scripts/run.py -e aaa

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

No reason at all for page_size to be in mmu.hh but huge_page_size in mmu.cc.
Move it, so we can also use huge_page_size outside the mmu.cc scope.

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Commit ed808267 used malloc() to allocate
the per-cpu variables area. As Avi pointed out, we need this area to be
aligned like the strictest alignment of any per-cpu variable. The strictest
alignment we need is probably CACHELINE_ALIGNED (64 bytes), but it's easiest
just to require 4096-byte alignment, and this is what the code prior to the
above patch did.

The above commit worked because luckily enough, our malloc() does return
page-aligned memory for large allocations. But it's possible that this will
not be the case in the future. So this patch switches to use aligned_alloc()
instead, explicitly requesting a 4096-byte-aligned block of memory.

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Reviewed-by: Pekka Enberg <penberg@cloudius-systems.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

This patch provides a trivial implementation of two similar functions for
allocating aligned memory blocks: aligned_alloc() (from the C11 standard)
and posix_memaligned() (from POSIX). Memory returned by either function
can be freed with the ordinary free().

This trivial implementation just calls malloc(), and assert()s that it got
the desired alignment, aborting if not. In many cases this is good enough
because malloc() already returns 4096-byte-aligned blocks for large
allocations. In particular we'll use these functions in the next patch for
allocating the large page-aligned per-cpu areas.

If we ever fail on this assertion, we can replace these functions by a
full implementation (see issue #87).

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Reviewed-by: Pekka Enberg <penberg@cloudius-systems.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

Some older version of qemu-nbd cuases error exit with nbd_client.py.
(Look at: https://groups.google.com/d/msg/osv-dev/EW5BtNFNfzs/I33BeFXg2f0J

)
This is because nbd_client.py is sending FLUSH command unconditionally, but it's extended feature, nbd client should check nbd server has the capability to accept FLUSH.
nbd server sends capability flags on negotiation stage, it sends HAS_FLAGS(0x1) and SEND_FLUSH(0x4) when server supports FLUSH.

This patch adds these capability check, and skips to send FLUSH if server doesn't support it.

Signed-off-by: Takuya ASADA <syuu@dokukino.com>
Reviewed-by: Benoît Canet <benoit.canet@irqsave.net>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

This patch reduces the size of the .percpu section 64-fold from about
5 MB to 70 KB, and solves issue #95.

The ".percpu" section is part of the .data section of our executable
(loader-stripped.elf). In our 15 MB executable, roughly 7 MB is text
(code), and 7 MB is data, and out of that, a whopping 5 MB is the
".percpu" section. The executable is read in real mode, and this is
especially slow on Amazon EC2, hence our wish to make the executable
as small as possible.

The percpu section starts with all the PERCPU variables defined in the
program. We have about 70 KB of those, and believe it or not, most of
this 70 KB is just a single variable, the 65K dynamic_percpu_buffer
(see percpu.cc).

But then, we need a copy of these variables for each CPU. The unpatched
code duplicated this 70KB section 64 times in the executable file (!),
and then used these memory locations for up-to-64 cpus. But there is
no reason to duplicate this data in the executable! All we need to do
is to dynamically allocate a copy of this section for each CPU, and
this is what this patch does.

This patch removes about 5 MB from our executable: After this patch,
our loader-stripped.elf is just 9.7 MB, and its data section's size is
just 2.8 MB.

Reviewed-by: Glauber Costa <glommer@cloudius-systems.com>
Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

vop_eperm allows more code reuse (suggested by Glauber Costa)

Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Use four spaces for indentation and use UNIX linefeeds.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Show running test case name.  Makes debugging test failures less
painful...

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Use the new pivot_root() functionality to switch to ZFS root filesystem
once OSv is up and running.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Needed by pivot_root() to unmount the initial rootfs.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

This adds a simple pivot_root() system call that works on mountpoints
and simply removes 'put_old' from mount list so that VFS doesn't know
about it and adds renames 'new_root' ->m_path to '/'.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Previously, fill only supported small-page-size chunks.  However, it's
possible to avoid calling fill multiple times simply by allowing
variable page sizes.

Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Commit 0dcf1f8f ("OSv module support") didn't add a dependency to
bootfs.manifest.skel and usr.manifest.skel which causes image not to be
rebuilt if the files are changed.

Fix that up.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Add pthread_kill() stub. Needed by Cassandra when its stopped with
Ctrl-C.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Add the actual test case that was forgotten from commit a9f8092a
("Introduce test for libc locking").

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>