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Niklas Schnelle f86ca2b553 s390/pci: Prevent self deletion in disable_slot() 
commit 47c3978448 upstream.

As disable_slot() takes a struct zpci_dev from the Configured to the
Standby state. In Standby there is still a hotplug slot so this is not
usually a case of sysfs self deletion. This is important because self
deletion gets very hairy in terms of locking (see for example
recover_store() in arch/s390/pci/pci_sysfs.c).

Because the pci_dev_put() is not within the critical section of the
zdev->state_lock however, disable_slot() can turn into a case of self
deletion if zPCI device event handling slips between the mutex_unlock()
and the pci_dev_put(). If the latter is the last put and
zpci_release_device() is called this then tries to remove the hotplug
slot via zpci_exit_slot() which will try to remove the hotplug slot
directory the disable_slot() is part of i.e. self deletion.

Prevent this by widening the zdev->state_lock critical section to
include the pci_dev_put() which is then guaranteed to happen with the
struct zpci_dev still in Standby state ensuring it will not lead to
a zpci_release_device() call as at least the zPCI event handling code
still holds a reference.

Cc: stable@vger.kernel.org
Fixes: a46044a92a ("s390/pci: fix zpci_zdev_put() on reserve")
Reviewed-by: Gerd Bayer <gbayer@linux.ibm.com>
Tested-by: Gerd Bayer <gbayer@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-06-27 11:11:14 +01:00
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README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.