Commit 060eabe8fb ("xenbus/backend: Protect xenbus callback with
lock") introduced a bug by holding a lock while calling a function
which might schedule.
Fix that by using a semaphore instead.
Fixes: 060eabe8fb ("xenbus/backend: Protect xenbus callback with lock")
Signed-off-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20200305100323.16736-1-jgross@suse.com
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
A driver's 'reclaim_memory' callback can race with 'probe' or 'remove'
because it will be called whenever memory pressure is detected. To
avoid such race, this commit embeds a spinlock in each 'xenbus_device'
and make 'xenbus' to hold the lock while the corresponded callbacks are
running.
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Granting pages consumes backend system memory. In systems configured
with insufficient spare memory for those pages, it can cause a memory
pressure situation. However, finding the optimal amount of the spare
memory is challenging for large systems having dynamic resource
utilization patterns. Also, such a static configuration might lack
flexibility.
To mitigate such problems, this commit adds a memory reclaim callback to
'xenbus_driver'. If a memory pressure is detected, 'xenbus' requests
every backend driver to volunarily release its memory.
Note that it would be able to improve the callback facility for more
sophisticated handlings of general pressures. For example, it would be
possible to monitor the memory consumption of each device and issue the
release requests to only devices which causing the pressure. Also, the
callback could be extended to handle not only memory, but general
resources. Nevertheless, this version of the implementation defers such
sophisticated goals as a future work.
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
...and make it static
xenbus_dev_shutdown() is seemingly intended to cause clean shutdown of PV
frontends when a guest is rebooted. Indeed the function waits for a
conpletion which is only set by a call to xenbus_frontend_closed().
This patch removes the shutdown() method from backends and moves
xenbus_dev_shutdown() from xenbus_probe.c into xenbus_probe_frontend.c,
renaming it appropriately and making it static.
NOTE: In the case where the backend is running in a driver domain, the
toolstack should have already terminated any frontends that may be
using it (since Xen does not support re-startable PV driver domains)
so xenbus_dev_shutdown() should never be called.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Today a Xenstore watch event is delivered via a callback function
declared as:
void (*callback)(struct xenbus_watch *,
const char **vec, unsigned int len);
As all watch events only ever come with two parameters (path and token)
changing the prototype to:
void (*callback)(struct xenbus_watch *,
const char *path, const char *token);
is the natural thing to do.
Apply this change and adapt all users.
Cc: konrad.wilk@oracle.com
Cc: roger.pau@citrix.com
Cc: wei.liu2@citrix.com
Cc: paul.durrant@citrix.com
Cc: netdev@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
The xenbus driver has an awful mixture of internally and globally
visible headers: some of the internally used only stuff is defined in
the global header include/xen/xenbus.h while some stuff defined in
internal headers is used by other drivers, too.
Clean this up by moving the externally used symbols to
include/xen/xenbus.h and the symbols used internally only to a new
header drivers/xen/xenbus/xenbus.h replacing xenbus_comms.h and
xenbus_probe.h
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Use xenbus_read_unsigned() instead of xenbus_scanf() when possible.
This requires to change the type of the reads from int to unsigned,
but these cases have been wrong before: negative values are not allowed
for the modified cases.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: David Vrabel <david.vrabel@citrix.com>
The DEFINE_XENBUS_DRIVER() macro looks a bit weird and causes sparse
errors.
Replace the uses with standard structure definitions instead. This is
similar to pci and usb device registration.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
The dev_attrs field of struct bus_type is going away soon, dev_groups
should be used instead. This converts the xenbus code to use the
correct field.
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: <xen-devel@lists.xenproject.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Convert printks to pr_<level> (excludes printk(KERN_DEBUG...)
to be more consistent throughout the xen subsystem.
Add pr_fmt with KBUILD_MODNAME or "xen:" KBUILD_MODNAME
Coalesce formats and add missing word spaces
Add missing newlines
Align arguments and reflow to 80 columns
Remove DRV_NAME from formats as pr_fmt adds the same content
This does change some of the prefixes of these messages
but it also does make them more consistent.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The 'name', 'owner', and 'mod_name' members are redundant with the
identically named fields in the 'driver' sub-structure. Rather than
switching each instance to specify these fields explicitly, introduce
a macro to simplify this.
Eliminate further redundancy by allowing the drvname argument to
DEFINE_XENBUS_DRIVER() to be blank (in which case the first entry from
the ID table will be used for .driver.name).
Also eliminate the questionable xenbus_register_{back,front}end()
wrappers - their sole remaining purpose was the checking of the
'owner' field, proper setting of which shouldn't be an issue anymore
when the macro gets used.
v2: Restore DRV_NAME for the driver name in xen-pciback.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Things like THIS_MODULE and EXPORT_SYMBOL were simply everywhere
because module.h was also everywhere. But we are fixing the latter.
So we need to call out the real users in advance.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
.. we check whether 'xdev' is NULL - but there is no need for
it as the 'dev' check is done before. The 'dev' is embedded in
the 'xdev' so having xdev != NULL with dev being being checked
is not going to happen.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
All the Xen backend drivers are assigned to a special bus type
xen-backend. This patch exports xen-backend:* names through modalias and
uevent to autoload them.
Signed-off-by: Bastian Blank <waldi@debian.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The xenbus bus type uses device_create_file to assign all used device
attributes. However it does not remove them when the device goes away.
This patch uses the dev_attrs field of the bus type to specify default
attributes for all devices.
Signed-off-by: Bastian Blank <waldi@debian.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
[corresponds to 98b833aaf81e in git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Impact: bugfix
Need to register it before any drivers want to attach.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
[corresponds to a7a9c3a942c6 in git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Impact: cleanup
It's a usermode header for users of /dev/xen/evtchn.
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
[corresponds to b60e48cec12f in git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Impact: backend device support
Add the basic machinery to support backend drivers.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
[corresponds to 79727b851bac in git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
