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path: root/drivers/counter/counter-chrdev.c
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2022-03-18counter: add defaults to switch-statementsTom Rix
Clang static analysis reports this representative problem counter-chrdev.c:482:3: warning: Undefined or garbage value returned to caller return ret; ^~~~~~~~~~ counter_get_data() has a multilevel switches, some without defaults, so ret is sometimes not set. Add returning -EINVAL similar to other defaults. Link: https://lore.kernel.org/r/20220227161746.82776-1-trix@redhat.com Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Acked-by: Syed Nayyar Waris <syednwaris@gmail.com> Signed-off-by: Tom Rix <trix@redhat.com> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com> Link: https://lore.kernel.org/r/b98d1a3ed4b0b324b261b23defd1bdddddba4d44.1647373009.git.vilhelm.gray@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-21counter: Fix use-after-free race condition for events_queue_size writeWilliam Breathitt Gray
A race condition is possible when writing to events_queue_size where the events kfifo is freed during the execution of a kfifo_in(), resulting in a use-after-free. This patch prevents such a scenario by protecting the events queue in operation with a spinlock and locking before performing the events queue size adjustment. The existing events_lock mutex is renamed to events_out_lock to reflect that it only protects events queue out operations. Because the events queue in operations can occur in an interrupt context, a new events_in_lock spinlock is introduced and utilized. Fixes: feff17a550c7 ("counter: Implement events_queue_size sysfs attribute") Cc: David Lechner <david@lechnology.com> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com> Link: https://lore.kernel.org/r/20211021103540.955639-1-vilhelm.gray@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-21counter: Cleanup lingering atomic.h includesWilliam Breathitt Gray
With the removal of the chrdev_lock atomic flag, the counter-sysfs.c and counter-chrdev.c no longer needs to include the atomic.h header file. Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com> Link: https://lore.kernel.org/r/20211021103514.955622-1-vilhelm.gray@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-19counter: drop chrdev_lockDavid Lechner
This removes the chrdev_lock from the counter subsystem. This was intended to prevent opening the chrdev more than once. However, this doesn't work in practice since userspace can duplicate file descriptors and pass file descriptors to other processes. Since this protection can't be relied on, it is best to just remove it. Suggested-by: Greg KH <gregkh@linuxfoundation.org> Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com> Signed-off-by: David Lechner <david@lechnology.com> Link: https://lore.kernel.org/r/20211017185521.3468640-1-david@lechnology.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-17counter: Add character device interfaceWilliam Breathitt Gray
This patch introduces a character device interface for the Counter subsystem. Device data is exposed through standard character device read operations. Device data is gathered when a Counter event is pushed by the respective Counter device driver. Configuration is handled via ioctl operations on the respective Counter character device node. Cc: David Lechner <david@lechnology.com> Cc: Gwendal Grignou <gwendal@chromium.org> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Oleksij Rempel <o.rempel@pengutronix.de> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com> Link: https://lore.kernel.org/r/b8b8c64b4065aedff43699ad1f0e2f8d1419c15b.1632884256.git.vilhelm.gray@gmail.com Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>