linux-stable.git/drivers/base/core.c, branch v4.19.232

PCI/MSI: Protect msi_desc::masked for multi-MSI

2021-08-26T12:36:41+00:00

commit 77e89afc25f30abd56e76a809ee2884d7c1b63ce upstream.

Multi-MSI uses a single MSI descriptor and there is a single mask register
when the device supports per vector masking. To avoid reading back the mask
register the value is cached in the MSI descriptor and updates are done by
clearing and setting bits in the cache and writing it to the device.

But nothing protects msi_desc::masked and the mask register from being
modified concurrently on two different CPUs for two different Linux
interrupts which belong to the same multi-MSI descriptor.

Add a lock to struct device and protect any operation on the mask and the
mask register with it.

This makes the update of msi_desc::masked unconditional, but there is no
place which requires a modification of the hardware register without
updating the masked cache.

msi_mask_irq() is now an empty wrapper which will be cleaned up in follow
up changes.

The problem goes way back to the initial support of multi-MSI, but picking
the commit which introduced the mask cache is a valid cut off point
(2.6.30).

Fixes: f2440d9acbe8 ("PCI MSI: Refactor interrupt masking code")
Signed-off-by: Thomas Gleixner 
Tested-by: Marc Zyngier 
Reviewed-by: Marc Zyngier 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210729222542.726833414@linutronix.de
Signed-off-by: Greg Kroah-Hartman

driver core: Extend device_is_dependent()

2021-01-27T10:05:42+00:00

commit 3d1cf435e201d1fd63e4346b141881aed086effd upstream.

If the device passed as the target (second argument) to
device_is_dependent() is not completely registered (that is, it has
been initialized, but not added yet), but the parent pointer of it
is set, it may be missing from the list of the parent's children
and device_for_each_child() called by device_is_dependent() cannot
be relied on to catch that dependency.

For this reason, modify device_is_dependent() to check the ancestors
of the target device by following its parent pointer in addition to
the device_for_each_child() walk.

Fixes: 9ed9895370ae ("driver core: Functional dependencies tracking support")
Reported-by: Stephan Gerhold 
Tested-by: Stephan Gerhold 
Reviewed-by: Saravana Kannan 
Signed-off-by: Rafael J. Wysocki 
Link: https://lore.kernel.org/r/17705994.d592GUb2YH@kreacher
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

Revert "device property: Keep secondary firmware node secondary by type"

2021-01-12T19:10:24+00:00

commit 47f4469970d8861bc06d2d4d45ac8200ff07c693 upstream.

While commit d5dcce0c414f ("device property: Keep secondary firmware
node secondary by type") describes everything correct in its commit
message, the change it made does the opposite and original commit
c15e1bdda436 ("device property: Fix the secondary firmware node handling
in set_primary_fwnode()") was fully correct.

Revert the former one here and improve documentation in the next patch.

Fixes: d5dcce0c414f ("device property: Keep secondary firmware node secondary by type")
Signed-off-by: Bard Liao 
Reviewed-by: Andy Shevchenko 
Reviewed-by: Heikki Krogerus 
Cc: 5.10+  # 5.10+
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

device property: Don't clear secondary pointer for shared primary firmware node

2020-11-05T10:08:55+00:00

commit 99aed9227073fb34ce2880cbc7063e04185a65e1 upstream.

It appears that firmware nodes can be shared between devices. In such case
when a (child) device is about to be deleted, its firmware node may be shared
and ACPI_COMPANION_SET(..., NULL) call for it breaks the secondary link
of the shared primary firmware node.

In order to prevent that, check, if the device has a parent and parent's
firmware node is shared with its child, and avoid crashing the link.

Fixes: c15e1bdda436 ("device property: Fix the secondary firmware node handling in set_primary_fwnode()")
Reported-by: Ferry Toth 
Signed-off-by: Andy Shevchenko 
Reviewed-by: Heikki Krogerus 
Tested-by: Ferry Toth 
Cc: 5.9+  # 5.9+
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

device property: Keep secondary firmware node secondary by type

2020-11-05T10:08:55+00:00

commit d5dcce0c414fcbfe4c2037b66ac69ea5f9b3f75c upstream.

Behind primary and secondary we understand the type of the nodes
which might define their ordering. However, if primary node gone,
we can't maintain the ordering by definition of the linked list.
Thus, by ordering secondary node becomes first in the list.
But in this case the meaning of it is still secondary (or auxiliary).
The type of the node is maintained by the secondary pointer in it:

	secondary pointer		Meaning
	NULL or valid			primary node
	ERR_PTR(-ENODEV)		secondary node

So, if by some reason we do the following sequence of calls

	set_primary_fwnode(dev, NULL);
	set_primary_fwnode(dev, primary);

we should preserve secondary node.

This concept is supported by the description of set_primary_fwnode()
along with implementation of set_secondary_fwnode(). Hence, fix
the commit c15e1bdda436 to follow this as well.

Fixes: c15e1bdda436 ("device property: Fix the secondary firmware node handling in set_primary_fwnode()")
Cc: Ferry Toth 
Signed-off-by: Andy Shevchenko 
Reviewed-by: Heikki Krogerus 
Tested-by: Ferry Toth 
Cc: 5.9+  # 5.9+
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

device property: Fix the secondary firmware node handling in set_primary_fwnode()

2020-09-03T09:24:29+00:00

commit c15e1bdda4365a5f17cdadf22bf1c1df13884a9e upstream.

When the primary firmware node pointer is removed from a
device (set to NULL) the secondary firmware node pointer,
when it exists, is made the primary node for the device.
However, the secondary firmware node pointer of the original
primary firmware node is never cleared (set to NULL).

To avoid situation where the secondary firmware node pointer
is pointing to a non-existing object, clearing it properly
when the primary node is removed from a device in
set_primary_fwnode().

Fixes: 97badf873ab6 ("device property: Make it possible to use secondary firmware nodes")
Cc: All applicable 
Signed-off-by: Heikki Krogerus 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

driver core: Fix creation of device links with PM-runtime flags

2020-03-20T10:55:58+00:00

commit fb583c8eeeb1fd57e24ef41ed94c9112067aeac9 upstream.

After commit 515db266a9da ("driver core: Remove device link creation
limitation"), if PM-runtime flags are passed to device_link_add(), it
will fail (returning NULL) due to an overly restrictive flags check
introduced by that commit.

Fix this issue by extending the check in question to cover the
PM-runtime flags too.

Fixes: 515db266a9da ("driver core: Remove device link creation limitation")
Reported-by: Dmitry Osipenko 
Tested-by: Jon Hunter 
Signed-off-by: Rafael J. Wysocki 
Tested-by: Dmitry Osipenko 
Tested-by: Marek Szyprowski 
Link: https://lore.kernel.org/r/7674989.cD04D8YV3U@kreacher
Signed-off-by: Saravana Kannan 
Signed-off-by: Greg Kroah-Hartman

driver core: Remove device link creation limitation

2020-03-20T10:55:58+00:00

commit 515db266a9dace92b0cbaed9a6044dd5304b8ca9 upstream.

If device_link_add() is called for a consumer/supplier pair with an
existing device link between them and the existing link's type is
not in agreement with the flags passed to that function by its
caller, NULL will be returned.  That is seriously inconvenient,
because it forces the callers of device_link_add() to worry about
what others may or may not do even if that is not relevant to them
for any other reasons.

It turns out, however, that this limitation can be made go away
relatively easily.

The underlying observation is that if DL_FLAG_STATELESS has been
passed to device_link_add() in flags for the given consumer/supplier
pair at least once, calling either device_link_del() or
device_link_remove() to release the link returned by it should work,
but there are no other requirements associated with that flag.  In
turn, if at least one of the callers of device_link_add() for the
given consumer/supplier pair has not passed DL_FLAG_STATELESS to it
in flags, the driver core should track the status of the link and act
on it as appropriate (ie. the link should be treated as "managed").
This means that DL_FLAG_STATELESS needs to be set for managed device
links and it should be valid to call device_link_del() or
device_link_remove() to drop references to them in certain
sutiations.

To allow that to happen, introduce a new (internal) device link flag
called DL_FLAG_MANAGED and make device_link_add() set it automatically
whenever DL_FLAG_STATELESS is not passed to it.  Also make it take
additional references to existing device links that were previously
stateless (that is, with DL_FLAG_STATELESS set and DL_FLAG_MANAGED
unset) and will need to be managed going forward and initialize
their status (which has been DL_STATE_NONE so far).

Accordingly, when a managed device link is dropped automatically
by the driver core, make it clear DL_FLAG_MANAGED, reset the link's
status back to DL_STATE_NONE and drop the reference to it associated
with DL_FLAG_MANAGED instead of just deleting it right away (to
allow it to stay around in case it still needs to be released
explicitly by someone).

With that, since setting DL_FLAG_STATELESS doesn't mean that the
device link in question is not managed any more, replace all of the
status-tracking checks against DL_FLAG_STATELESS with analogous
checks against DL_FLAG_MANAGED and update the documentation to
reflect these changes.

While at it, make device_link_add() reject flags that it does not
recognize, including DL_FLAG_MANAGED.

Signed-off-by: Rafael J. Wysocki 
Reviewed-by: Saravana Kannan 
Tested-by: Marek Szyprowski 
Review-by: Saravana Kannan 
Link: https://lore.kernel.org/r/2305283.AStDPdUUnE@kreacher
Signed-off-by: Saravana Kannan 
Signed-off-by: Greg Kroah-Hartman

driver core: Add device link flag DL_FLAG_AUTOPROBE_CONSUMER

2020-03-20T10:55:58+00:00

commit e7dd40105aac9ba051e44ad711123bc53a5e4c71 upstream.

Add a new device link flag, DL_FLAG_AUTOPROBE_CONSUMER, to request the
driver core to probe for a consumer driver automatically after binding
a driver to the supplier device on a persistent managed device link.

As unbinding the supplier driver on a managed device link causes the
consumer driver to be detached from its device automatically, this
flag provides a complementary mechanism which is needed to address
some "composite device" use cases.

Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Saravana Kannan 
Signed-off-by: Greg Kroah-Hartman

driver core: Make driver core own stateful device links

2020-03-20T10:55:58+00:00

commit 72175d4ea4c442d95cf690c3e968eeee90fd43ca upstream.

Even though stateful device links are managed by the driver core in
principle, their creators are allowed and sometimes even expected
to drop references to them via device_link_del() or
device_link_remove(), but that doesn't really play well with the
"persistent" link concept.

If "persistent" managed device links are created from driver
probe callbacks, device_link_add() called to do that will take a
new reference on the link each time the callback runs and those
references will never be dropped, which kind of isn't nice.

This issues arises because of the link reference counting carried
out by device_link_add() for existing links, but that is only done to
avoid deleting device links that may still be necessary, which
shouldn't be a concern for managed (stateful) links.  These device
links are managed by the driver core and whoever creates one of them
will need it at least as long as until the consumer driver is detached
from its device and deleting it may be left to the driver core just
fine.

For this reason, rework device_link_add() to apply the reference
counting to stateless links only and make device_link_del() and
device_link_remove() drop references to stateless links only too.
After this change, if called to add a stateful device link for
a consumer-supplier pair for which a stateful device link is
present already, device_link_add() will return the existing link
without incrementing its reference counter.  Accordingly,
device_link_del() and device_link_remove() will WARN() and do
nothing when called to drop a reference to a stateful link.  Thus,
effectively, all stateful device links will be owned by the driver
core.

In addition, clean up the handling of the link management flags,
DL_FLAG_AUTOREMOVE_CONSUMER and DL_FLAG_AUTOREMOVE_SUPPLIER, so that
(a) they are never set at the same time and (b) if device_link_add()
is called for a consumer-supplier pair with an existing stateful link
between them, the flags of that link will be combined with the flags
passed to device_link_add() to ensure that the life time of the link
is sufficient for all of the callers of device_link_add() for the
same consumer-supplier pair.

Update the device_link_add() kerneldoc comment to reflect the
above changes.

Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Saravana Kannan 
Signed-off-by: Greg Kroah-Hartman