module: Wait for RCU synchronizing before releasing a module

Wait for RCU synchronizing on failure path of module loading
before releasing struct module, because the memory of mod->list
can still be accessed by list walkers (e.g. kallsyms).

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
module: Unlink module with RCU synchronizing instead of stop_machine

Unlink module from module list with RCU synchronizing instead
of using stop_machine(). Since module list is already protected
by rcu, we don't need stop_machine() anymore.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
lib/bug: Use RCU list ops for module_bug_list

Actually since module_bug_list should be used in BUG context,
we may not need this. But for someone who want to use this
from normal context, this makes module_bug_list an RCU list.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
module: Replace module_ref with atomic_t refcnt

Replace module_ref per-cpu complex reference counter with
an atomic_t simple refcnt. This is for code simplification.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
module: Remove stop_machine from module unloading

Remove stop_machine from module unloading by adding new reference
counting algorithm.

This atomic refcounter works like a semaphore, it can get (be
incremented) only when the counter is not 0. When loading a module,
kmodule subsystem sets the counter MODULE_REF_BASE (= 1). And when
unloading the module, it subtracts MODULE_REF_BASE from the counter.
If no one refers the module, the refcounter becomes 0 and we can
remove the module safely. If someone referes it, we try to recover
the counter by adding MODULE_REF_BASE unless the counter becomes 0,
because the referrer can put the module right before recovering.
If the recovering is failed, we can get the 0 refcount and it
never be incremented again, it can be removed safely too.

Note that __module_get() forcibly gets the module refcounter,
users should use try_module_get() instead of that.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
kernel:module Fix coding style errors and warnings.

Fixed codin style errors and warnings. Changes printk with
print_debug/warn. Changed seq_printf to seq_puts.

Signed-off-by: Ionut Alexa <ionut.m.alexa@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (removed bogus KERN_DEFAULT conversion)
params: cleanup sysfs allocation

commit 63662139e519ce06090b2759cf4a1d291b9cc0e2 attempted to patch a
leak (which would only happen on OOM, ie. never), but it didn't quite
work.

This rewrites the code to be as simple as possible.  add_sysfs_param()
adds a parameter.  If it fails, it's the caller's responsibility to
clean up the parameters which already exist.

The kzalloc-then-always-krealloc pattern is perhaps overly simplistic,
but this code has clearly confused people.  It worked on me...

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
virtio: set VIRTIO_CONFIG_S_FEATURES_OK on restore

virtio 1.0 devices require that drivers set VIRTIO_CONFIG_S_FEATURES_OK
after finalizing features.
virtio core missed doing this on restore, fix it up.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
virtio_config: fix virtio_cread_bytes

virtio_cread_bytes is implemented incorrectly in case length happens to
be 2,4 or 8 bytes: transports and devices will assume it's an integer
value that has to be converted to LE format.

Let's just do multiple 1-byte reads: this also makes life easier
for transports who only need to implement 1,2,4 and 8 byte reads.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
virtio_pci_common.h: drop VIRTIO_PCI_NO_LEGACY

Legacy drivers use virtio_pci_common.h too, we should not
define VIRTIO_PCI_NO_LEGACY there.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
virtio_pci: move probe to common file

It turns out this make everything easier.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
virtio_pci: add VIRTIO_PCI_NO_LEGACY

Add macro to disable all legacy register defines.
Helpful to make sure legacy macros don't leak
through into modern code.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
virtio: core support for config generation

virtio 1.0 spec says:

Drivers MUST NOT assume reads from fields greater than 32 bits wide are
atomic, nor are reads from multiple fields: drivers SHOULD read device
configuration space fields like so:
	u32 before, after;
	do {
		before = get_config_generation(device);
		// read config entry/entries.
		after = get_config_generation(device);
	} while (after != before);

Do exactly this, for transports that support it.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
tools/virtio: more stubs

As usual, add more stubs to fix test build after main
codebase changes.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
tools/virtio: fix vringh test

Include missing virtio_config.h

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
tools/virtio: 64 bit features

Missed one place where vringh_test used
long to pass features. Fix it up to u64.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
tools/virtio: enable -Werror

Seems to mostly be a positive.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
tools/virtio: add virtio 1.0 in virtio_test

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
tools/virtio: add virtio 1.0 in vringh_test

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
vringh: 64 bit features

Pass u64 everywhere.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>