Readability: a postfix increment is used on a pointer which is not
used anywhere afterwards, which may send the reader looking through
the function one extra time. Drop the unnecessary increment.
Reported-by: Alan Cox <alan.cox@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Laurent Fert <laurent.fert@intel.com>
Currently, stm_register_device() makes the device visible and then
proceeds to initializing spinlocks and other properties, which leaves
a window when the device can already be opened but is not yet fully
operational.
Fix this by reversing the initialization order.
Reported-by: Alan Cox <alan.cox@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Laurent Fert <laurent.fert@intel.com>
Currently, the error path of stm_register_device() forgets to unregister
the chrdev. Fix this.
Reported-by: Alan Cox <alan.cox@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Laurent Fert <laurent.fert@intel.com>
No point in explicitly setting something to zero right after we
explicitly checked that it is zero. Fix this.
Reported-by: Alan Cox <alan.cox@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Laurent Fert <laurent.fert@intel.com>
Changing nr_devs after the module has been loaded doesn't actually
change anything, so just make it read-only.
Reported-by: Alan Cox <alan.cox@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Laurent Fert <laurent.fert@intel.com>
Changing nr_dummies after the module has been loaded doesn't actually
change anything, so just make it read-only.
Reported-by: Alan Cox <alan.cox@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Laurent Fert <laurent.fert@intel.com>
Master IDs are of unsigned int type, yet in the configfs policy code
we're validating user's input against INT_MAX. This is both pointless
and misleading as the real limits are imposed by the stm device's
[sw_start..sw_end] (which are also limited by the spec to be no larger
than 2^16-1).
Clean this up by getting rid of the redundant comparisons.
Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Laurent Fert <laurent.fert@intel.com>
STM device's link callback has the power to abort master/channel
assignment by returning a negative error code. Use this in dummy
stm device to optionally abort assigning certain channel IDs.
This is useful as fault injection into the stm class core, for
testing purposes.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
STM device's unlink callback is never actually called from anywhere in
the stm class code.
This patch adds calls to stm driver's unlink method after the unlinking
has succeeded.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There is a window in stm_source_link_drop(), during which the source's
link may change before locks are acquired. When this happens, it throws
a warning, since this is not an expected scenario.
This patch handles the race in such a way that if the link appears to
have changed by the time we took the locks, it will release them and
repeat the whole unlinking procedure from the beginning, unless the
other contender beat us to it.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
STM code takes references to the stm device and its module for the
duration of the character device's existence or the stm_source link.
Dropping these references is not well balanced everywhere, which may
lead to leaks.
This patch balances the acquisition and releasing of these two
references and annotates each site so that it's easier to verify
correctness by reading the code.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It is possible to concurrently assign the same output (a character
device writer or an stm_source device) to different stm devices,
which sets off a strategically placed warning in stm_output_assign().
To avoid this, use a spinlock to serialize (un)assignments between
outputs and stm devices.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
If an illegal attempt is made to unlink stm source device from an
stm device, the stm device's link spinlock mistakenly remains locked.
While this really shouldn't happen (there's a warning in place), the
locking should remain in order so that we can still recover from this
situation if it indeed does happen.
This patch unifies the unlocking in the exit path of
__stm_source_link_drop() to fix this.
Reported-by: Laurent Fert <laurent.fert@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Heartbeat stm source may have multiple instances (for connecting to
different stm devices). Each instance will send a periodic test message
over its stm device when it is linked. This can be used for testing stm
class framework, stm device drivers or as a heartbeat over the stm link.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
STM framework should be able to handle multiple STM devices at a time,
each one with its own master allocation policy.
This patch changes dummy_stm driver to create multiple STM sinks to
help testing the framework.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
By convention, the name of the stm policy directory in configfs consists of
the device name to which it applies and the actual policy name, separated
by a dot. Now, some devices already have dots in their names that separate
name of the actual device from its instance identifier. Such devices will
result in two (or more, who can tell) dots in the policy directory name.
Existing policy code, however, will treat the first dot as the one that
separates device name from policy name, therefore failing the above case.
This patch makes the last dot in the directory name be the separator, thus
prohibiting dots from being used in policy names.
Suggested-by: Chunyan Zhang <zhang.chunyan@linaro.org>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
STM drivers provide a callback to generate/send individual STP packets;
it also tells the stm core how many bytes of payload it has consumed.
However, we would also need to use the negative space of this return
value to communicate errors that occur during the packet generation,
in which case the stm core will have to take appropriate action.
For now, we need to account for the possibility that the stm driver may
not support certain combinations of packet type/flags, in which case
it is expected to signal an error.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The device unregister path uses wrong master index range when it tries
to free the allocated masters, it should, as does the rest of the stm
class code, use real master IDs.
This patch fixes the device unregister path to use real master IDs to
avoid memory leaks after unloading the stm driver.
Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
[alexander.shishkin@intel.com: re-wrote the commit message]
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The return type "unsigned int" was used by the stm_find_master_chan function
despite of the aspect that it will eventually return a negative error code.
Done with the help of Coccinelle.
Signed-off-by: Lucas Tanure <tanure@linux.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, the character device write method allocates a temporary buffer
for user's data, but the user's data size is not sanitized and can cause
arbitrarily large allocations via kzalloc() or an integer overflow that
will then result in overwriting kernel memory.
This patch trims the input buffer size to avoid these issues.
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since both sw_start and sw_end are master indices, the size of array
that holds them is sw_end - sw_start + 1, which the current code gets
wrong, allocating one item less than required.
This patch corrects the allocation size, avoiding potential slab
corruption.
Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
[alexander.shishkin@linux.intel.com: re-wrote the commit message]
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, the list of stm_sources linked to an stm device is protected by
a spinlock, which also means that sources' .unlink() method is called under
this spinlock. However, this method may (and does) sleep, which means
trouble.
This patch slightly reworks locking around stm::link_list so that bits that
might_sleep() are called with a mutex held instead. Modification of this
list requires both mutex and spinlock to be held, while looking at the list
can be done under either mutex or spinlock.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Right now, if stm device removal has to unbind from a policy (that is,
an stm device that has STP policy, gets removed), it will trigger a
nested lock on the stm device's policy mutex.
This patch fixes the problem by moving the locking from the policy
unbinding to policy removal (configfs path), where it's actually needed;
the other caller of the policy unbinding function already takes the
mutex around the call.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The newly added STM code uses SRCU, but does not ensure that
this code is part of the kernel:
drivers/built-in.o: In function `stm_source_link_show':
include/linux/srcu.h:221: undefined reference to `__srcu_read_lock'
include/linux/srcu.h:238: undefined reference to `__srcu_read_unlock'
drivers/built-in.o: In function `stm_source_link_drop':
include/linux/srcu.h:221: undefined reference to `__srcu_read_lock'
include/linux/srcu.h:238: undefined reference to `__srcu_read_unlock'
This adds a Kconfig 'select' statement like all the other SRCU using
drivers have.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 7bd1d4093c ("stm class: Introduce an abstraction for System Trace Module devices")
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
If STM=n, it doesn't make sense to ask about STM_DUMMY and
STM_SOURCE_CONSOLE support, which are not even built when enabled
anyway. Hence hide these options if STM=n.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull SCSI target updates from Nicholas Bellinger:
"This series contains HCH's changes to absorb configfs attribute
->show() + ->store() function pointer usage from it's original
tree-wide consumers, into common configfs code.
It includes usb-gadget, target w/ drivers, netconsole and ocfs2
changes to realize the improved simplicity, that now renders the
original include/target/configfs_macros.h CPP magic for fabric drivers
and others, unnecessary and obsolete.
And with common code in place, new configfs attributes can be added
easier than ever before.
Note, there are further improvements in-flight from other folks for
v4.5 code in configfs land, plus number of target fixes for post -rc1
code"
In the meantime, a new user of the now-removed old configfs API came in
through the char/misc tree in commit 7bd1d4093c ("stm class: Introduce
an abstraction for System Trace Module devices").
This merge resolution comes from Alexander Shishkin, who updated his stm
class tracing abstraction to account for the removal of the old
show_attribute and store_attribute methods in commit 517982229f
("configfs: remove old API") from this pull. As Alexander says about
that patch:
"There's no need to keep an extra wrapper structure per item and the
awkward show_attribute/store_attribute item ops are no longer needed.
This patch converts policy code to the new api, all the while making
the code quite a bit smaller and easier on the eyes.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>"
That patch was folded into the merge so that the tree should be fully
bisectable.
* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: (23 commits)
configfs: remove old API
ocfs2/cluster: use per-attribute show and store methods
ocfs2/cluster: move locking into attribute store methods
netconsole: use per-attribute show and store methods
target: use per-attribute show and store methods
spear13xx_pcie_gadget: use per-attribute show and store methods
dlm: use per-attribute show and store methods
usb-gadget/f_serial: use per-attribute show and store methods
usb-gadget/f_phonet: use per-attribute show and store methods
usb-gadget/f_obex: use per-attribute show and store methods
usb-gadget/f_uac2: use per-attribute show and store methods
usb-gadget/f_uac1: use per-attribute show and store methods
usb-gadget/f_mass_storage: use per-attribute show and store methods
usb-gadget/f_sourcesink: use per-attribute show and store methods
usb-gadget/f_printer: use per-attribute show and store methods
usb-gadget/f_midi: use per-attribute show and store methods
usb-gadget/f_loopback: use per-attribute show and store methods
usb-gadget/ether: use per-attribute show and store methods
usb-gadget/f_acm: use per-attribute show and store methods
usb-gadget/f_hid: use per-attribute show and store methods
...
STM policy handling is basically configfs, I honestly don't know how we
ended up without a Kconfig dependency, but thanks to randconfig testing,
it's now caught.
Reported-by: Jim Davis <jim.epost@gmail.com>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Source device's link is protected with srcu, mark it as such to have
proper build-time validation of accesses to this field. The update
side that's dereferencing it under an update lock also needs an
accessor to dereference this field to keep sparse happy.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This is a simple stm_source class device driver (kernelspace stm trace
source) that registers a console and sends kernel messages over STM
devices.
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This is a simple module that pretends to be an stm device and discards
all the data that comes in. Useful for testing stm class and its users.
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A System Trace Module (STM) is a device exporting data in System Trace
Protocol (STP) format as defined by MIPI STP standards. Examples of such
devices are Intel(R) Trace Hub and Coresight STM.
This abstraction provides a unified interface for software trace sources
to send their data over an STM device to a debug host. In order to do
that, such a trace source needs to be assigned a pair of master/channel
identifiers that all the data from this source will be tagged with. The
STP decoder on the debug host side will use these master/channel tags to
distinguish different trace streams from one another inside one STP
stream.
This abstraction provides a configfs-based policy management mechanism
for dynamic allocation of these master/channel pairs based on trace
source-supplied string identifier. It has the flexibility of being
defined at runtime and at the same time (provided that the policy
definition is aligned with the decoding end) consistency.
For userspace trace sources, this abstraction provides write()-based and
mmap()-based (if the underlying stm device allows this) output mechanism.
For kernel-side trace sources, we provide "stm_source" device class that
can be connected to an stm device at run time.
Cc: linux-api@vger.kernel.org
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
