Commit Graph

196 Commits

Author SHA1 Message Date
Greg Kroah-Hartman e5019b1423 Merge 6.9-rc5 into driver-core-next
We want the kernfs fixes in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-04-23 13:27:43 +02:00
Lukas Wunner d48c03198a sysfs: Add sysfs_bin_attr_simple_read() helper
When drivers expose a bin_attribute in sysfs which is backed by a buffer
in memory, a common pattern is to set the @private and @size members in
struct bin_attribute to the buffer's location and size.

The ->read() callback then merely consists of a single memcpy() call.
It's not even necessary to perform bounds checks as these are already
handled by sysfs_kf_bin_read().

However each driver is so far providing its own ->read() implementation.
The pattern is sufficiently frequent to merit a public helper, so add
sysfs_bin_attr_simple_read() as well as BIN_ATTR_SIMPLE_RO() and
BIN_ATTR_SIMPLE_ADMIN_RO() macros to ease declaration of such
bin_attributes and reduce LoC and .text section size.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/5ed62b197a442ec6db53d8746d9d806dd0576e2d.1712410202.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-04-11 16:02:25 +02:00
Alan Stern a90bca2228 fs: sysfs: Fix reference leak in sysfs_break_active_protection()
The sysfs_break_active_protection() routine has an obvious reference
leak in its error path.  If the call to kernfs_find_and_get() fails then
kn will be NULL, so the companion sysfs_unbreak_active_protection()
routine won't get called (and would only cause an access violation by
trying to dereference kn->parent if it was called).  As a result, the
reference to kobj acquired at the start of the function will never be
released.

Fix the leak by adding an explicit kobject_put() call when kn is NULL.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Fixes: 2afc9166f7 ("scsi: sysfs: Introduce sysfs_{un,}break_active_protection()")
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: stable@vger.kernel.org
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/8a4d3f0f-c5e3-4b70-a188-0ca433f9e6f9@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-04-11 15:16:48 +02:00
Valentine Sinitsyn 0fedefd4c4 kernfs: sysfs: support custom llseek method for sysfs entries
As of now, seeking in sysfs files is handled by generic_file_llseek().
There are situations where one may want to customize seeking logic:

- Many sysfs entries are fixed files while generic_file_llseek() accepts
  past-the-end positions. Not only being useless by itself, this
  also means a bug in userspace code will trigger not at lseek(), but at
  some later point making debugging harder.
- generic_file_llseek() relies on f_mapping->host to get the file size
  which might not be correct for all sysfs entries.
  See commit 636b21b501 ("PCI: Revoke mappings like devmem") as an example.

Implement llseek method to override this behavior at sysfs attribute
level. The method is optional, and if it is absent,
generic_file_llseek() is called to preserve backwards compatibility.

Signed-off-by: Valentine Sinitsyn <valesini@yandex-team.ru>
Link: https://lore.kernel.org/r/20230925084013.309399-1-valesini@yandex-team.ru
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-10-05 13:42:11 +02:00
Greg Kroah-Hartman cdb4f26a63 kobject: kobj_type: remove default_attrs
Now that all in-kernel users of default_attrs for the kobj_type are gone
and converted to properly use the default_groups pointer instead, it can
be safely removed.

There is one standard way to create sysfs files in a kobj_type, and not
two like before, causing confusion as to which should be used.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20220106133151.607703-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-04-05 15:39:19 +02:00
Christoph Hellwig 820879ee18 sysfs: simplify sysfs_kf_seq_show
Contrary to the comment ->show is never called from lseek for sysfs,
given that sysfs does not use seq_lseek.  So remove the NULL ->show
case and just WARN and return an error if some future code path ends
up here.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210913054121.616001-7-hch@lst.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-09-14 17:03:01 +02:00
Christoph Hellwig d1a1a9606e sysfs: refactor sysfs_add_file_mode_ns
Regroup the code so that preallocated attributes and normal attributes are
handled in clearly separate blocks.

Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210913054121.616001-6-hch@lst.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-09-14 17:02:58 +02:00
Christoph Hellwig 5cf3bb0d3a sysfs: split out binary attribute handling from sysfs_add_file_mode_ns
Split adding binary attributes into a separate handler instead of
overloading sysfs_add_file_mode_ns.

Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210913054121.616001-5-hch@lst.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-09-14 16:59:46 +02:00
Krzysztof Wilczyński f06aff924f sysfs: Rename struct bin_attribute member to f_mapping
There are two users of iomem_get_mapping(), the struct file and struct
bin_attribute.  The former has a member called "f_mapping" and the
latter has a member called "mapping", and both are poniters to struct
address_space.

Rename struct bin_attribute member to "f_mapping" to keep both meaning
and the usage consistent with other users of iomem_get_mapping().

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Link: https://lore.kernel.org/r/20210729233235.1508920-3-kw@linux.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-08-05 14:47:31 +02:00
Krzysztof Wilczyński 93bb8e352a sysfs: Invoke iomem_get_mapping() from the sysfs open callback
Defer invocation of the iomem_get_mapping() to the sysfs open callback
so that it can be executed as needed when the binary sysfs object has
been accessed.

To do that, convert the "mapping" member of the struct bin_attribute
from a pointer to the struct address_space into a function pointer with
a signature that requires the same return type, and then updates the
sysfs_kf_bin_open() to invoke provided function should the function
pointer be valid.

Also, convert every invocation of iomem_get_mapping() into a function
pointer assignment, therefore allowing for the iomem_get_mapping()
invocation to be deferred to when the sysfs open callback runs.

Thus, this change removes the need for the fs_initcalls to complete
before any other sub-system that uses the iomem_get_mapping() would be
able to invoke it safely without leading to a failure and an Oops
related to an invalid iomem_get_mapping() access.

Suggested-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Link: https://lore.kernel.org/r/20210729233235.1508920-2-kw@linux.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-08-05 14:47:31 +02:00
Daniel Vetter 74b3019539 sysfs: Support zapping of binary attr mmaps
We want to be able to revoke pci mmaps so that the same access rules
applies as for /dev/kmem. Revoke support for devmem was added in
3234ac664a ("/dev/mem: Revoke mappings when a driver claims the
region").

The simplest way to achieve this is by having the same filp->f_mapping
for all mappings, so that unmap_mapping_range can find them all, no
matter through which file they've been created. Since this must be set
at open time we need sysfs support for this.

Add an optional mapping parameter bin_attr, which is only consulted
when there's also an mmap callback, since without mmap support
allowing to adjust the ->f_mapping makes no sense.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kees Cook <keescook@chromium.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: linux-mm@kvack.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: linux-media@vger.kernel.org
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Nayna Jain <nayna@linux.ibm.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20201127164131.2244124-12-daniel.vetter@ffwll.ch
2021-01-12 14:26:31 +01:00
Joe Perches 2efc459d06 sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output
Output defects can exist in sysfs content using sprintf and snprintf.

sprintf does not know the PAGE_SIZE maximum of the temporary buffer
used for outputting sysfs content and it's possible to overrun the
PAGE_SIZE buffer length.

Add a generic sysfs_emit function that knows that the size of the
temporary buffer and ensures that no overrun is done.

Add a generic sysfs_emit_at function that can be used in multiple
call situations that also ensures that no overrun is done.

Validate the output buffer argument to be page aligned.
Validate the offset len argument to be within the PAGE_SIZE buf.

Signed-off-by: Joe Perches <joe@perches.com>
Link: https://lore.kernel.org/r/884235202216d464d61ee975f7465332c86f76b2.1600285923.git.joe@perches.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-02 12:02:30 +02:00
Linus Torvalds 242b233198 RDMA 5.8 merge window pull request
A few large, long discussed works this time. The RNBD block driver has
 been posted for nearly two years now, and the removal of FMR has been a
 recurring discussion theme for a long time. The usual smattering of
 features and bug fixes.
 
 - Various small driver bugs fixes in rxe, mlx5, hfi1, and efa
 
 - Continuing driver cleanups in bnxt_re, hns
 
 - Big cleanup of mlx5 QP creation flows
 
 - More consistent use of src port and flow label when LAG is used and a
   mlx5 implementation
 
 - Additional set of cleanups for IB CM
 
 - 'RNBD' network block driver and target. This is a network block RDMA
   device specific to ionos's cloud environment. It brings strong multipath
   and resiliency capabilities.
 
 - Accelerated IPoIB for HFI1
 
 - QP/WQ/SRQ ioctl migration for uverbs, and support for multiple async fds
 
 - Support for exchanging the new IBTA defiend ECE data during RDMA CM
   exchanges
 
 - Removal of the very old and insecure FMR interface from all ULPs and
   drivers. FRWR should be preferred for at least a decade now.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma

Pull rdma updates from Jason Gunthorpe:
 "A more active cycle than most of the recent past, with a few large,
  long discussed works this time.

  The RNBD block driver has been posted for nearly two years now, and
  flowing through RDMA due to it also introducing a new ULP.

  The removal of FMR has been a recurring discussion theme for a long
  time.

  And the usual smattering of features and bug fixes.

  Summary:

   - Various small driver bugs fixes in rxe, mlx5, hfi1, and efa

   - Continuing driver cleanups in bnxt_re, hns

   - Big cleanup of mlx5 QP creation flows

   - More consistent use of src port and flow label when LAG is used and
     a mlx5 implementation

   - Additional set of cleanups for IB CM

   - 'RNBD' network block driver and target. This is a network block
     RDMA device specific to ionos's cloud environment. It brings strong
     multipath and resiliency capabilities.

   - Accelerated IPoIB for HFI1

   - QP/WQ/SRQ ioctl migration for uverbs, and support for multiple
     async fds

   - Support for exchanging the new IBTA defiend ECE data during RDMA CM
     exchanges

   - Removal of the very old and insecure FMR interface from all ULPs
     and drivers. FRWR should be preferred for at least a decade now"

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: (247 commits)
  RDMA/cm: Spurious WARNING triggered in cm_destroy_id()
  RDMA/mlx5: Return ECE DC support
  RDMA/mlx5: Don't rely on FW to set zeros in ECE response
  RDMA/mlx5: Return an error if copy_to_user fails
  IB/hfi1: Use free_netdev() in hfi1_netdev_free()
  RDMA/hns: Uninitialized variable in modify_qp_init_to_rtr()
  RDMA/core: Move and rename trace_cm_id_create()
  IB/hfi1: Fix hfi1_netdev_rx_init() error handling
  RDMA: Remove 'max_map_per_fmr'
  RDMA: Remove 'max_fmr'
  RDMA/core: Remove FMR device ops
  RDMA/rdmavt: Remove FMR memory registration
  RDMA/mthca: Remove FMR support for memory registration
  RDMA/mlx4: Remove FMR support for memory registration
  RDMA/i40iw: Remove FMR leftovers
  RDMA/bnxt_re: Remove FMR leftovers
  RDMA/mlx5: Remove FMR leftovers
  RDMA/core: Remove FMR pool API
  RDMA/rds: Remove FMR support for memory registration
  RDMA/srp: Remove support for FMR memory registration
  ...
2020-06-05 14:05:57 -07:00
Jack Wang 9ddacff18b sysfs: export sysfs_remove_file_self()
Function is going to be used in transport over RDMA module in subsequent
patches, so export it to GPL modules.

Link: https://lore.kernel.org/r/20200511135131.27580-2-danil.kipnis@cloud.ionos.com
Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: linux-kernel@vger.kernel.org
[jwang: extend the commit message]
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
2020-05-17 18:57:12 -03:00
Mauro Carvalho Chehab 0c1bc6b845 docs: filesystems: fix renamed references
Some filesystem references got broken by a previous patch
series I submitted. Address those.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Acked-by: David Sterba <dsterba@suse.com> # fs/affs/Kconfig
Link: https://lore.kernel.org/r/57318c53008dbda7f6f4a5a9e5787f4d37e8565a.1586881715.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-04-20 15:45:22 -06:00
Christian Brauner 2c4f9401ce sysfs: add sysfs_change_owner()
Add a helper to change the owner of sysfs objects.
This function will be used to correctly account for kobject ownership
changes, e.g. when moving network devices between network namespaces.

This mirrors how a kobject is added through driver core which in its guts is
done via kobject_add_internal() which in summary creates the main directory via
create_dir(), populates that directory with the groups associated with the
ktype of the kobject (if any) and populates the directory with the basic
attributes associated with the ktype of the kobject (if any). These are the
basic steps that are associated with adding a kobject in sysfs.
Any additional properties are added by the specific subsystem itself (not by
driver core) after it has registered the device. So for the example of network
devices, a network device will e.g. register a queue subdirectory under the
basic sysfs directory for the network device and than further subdirectories
within that queues subdirectory.  But that is all specific to network devices
and they call the corresponding sysfs functions to do that directly when they
create those queue objects. So anything that a subsystem adds outside of what
driver core does must also be changed by it (That's already true for removal of
files it created outside of driver core.) and it's the same for ownership
changes.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-26 20:07:25 -08:00
Christian Brauner 0666a3aee7 sysfs: add sysfs_link_change_owner()
Add a helper to change the owner of a sysfs link.
This function will be used to correctly account for kobject ownership
changes, e.g. when moving network devices between network namespaces.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-26 20:07:25 -08:00
Christian Brauner f70ce18568 sysfs: add sysfs_file_change_owner()
Add helpers to change the owner of a sysfs files.
This function will be used to correctly account for kobject ownership
changes, e.g. when moving network devices between network namespaces.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-26 20:07:25 -08:00
Ondrej Mosnacek 5b2f2bd62e sysfs: remove unused include of kernfs-internal.h
This include is not needed (fs/sysfs/file.c builds just fine without
it). Remove it.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-02-08 12:57:31 +01:00
Stephen Martin 4bd4e92cfe sysfs: fix blank line coding style warning
Fixed a coding style issue.

Signed-off-by: Stephen Martin <lockwood@opperline.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-01-18 16:45:17 +01:00
Greg Kroah-Hartman de96e9fea7 sysfs: convert BUG_ON to WARN_ON
It's rude to crash the system just because the developer did something
wrong, as it prevents them from usually even seeing what went wrong.

So convert the few BUG_ON() calls that have snuck into the sysfs code
over the years to WARN_ON() to make it more "friendly".  All of these
are able to be recovered from, so it makes no sense to crash.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-01-07 08:53:32 +01:00
Jani Nikula 9ee4685c9a sysfs: constify sysfs create/remove files harder
Let the passed in array be const (and thus placed in rodata) instead of
a mutable array of const pointers.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181004143750.30880-1-jani.nikula@intel.com
2018-12-03 18:18:19 +02:00
Linus Torvalds 72f02ba66b SCSI misc on 20180815
This is mostly updates to the usual drivers: mpt3sas, lpfc, qla2xxx,
 hisi_sas, smartpqi, megaraid_sas, arcmsr.  In addition, with the
 continuing absence of Nic we have target updates for tcmu and target
 core (all with reviews and acks).  The biggest observable change is
 going to be that we're (again) trying to switch to mulitqueue as the
 default (a user can still override the setting on the kernel command
 line).  Other major core stuff is the removal of the remaining
 Microchannel drivers, an update of the internal timers and some
 reworks of completion and result handling.
 
 Signed-off-by: James E.J. Bottomley <jejb@linux.vnet.ibm.com>
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Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

Pull SCSI updates from James Bottomley:
 "This is mostly updates to the usual drivers: mpt3sas, lpfc, qla2xxx,
  hisi_sas, smartpqi, megaraid_sas, arcmsr.

  In addition, with the continuing absence of Nic we have target updates
  for tcmu and target core (all with reviews and acks).

  The biggest observable change is going to be that we're (again) trying
  to switch to mulitqueue as the default (a user can still override the
  setting on the kernel command line).

  Other major core stuff is the removal of the remaining Microchannel
  drivers, an update of the internal timers and some reworks of
  completion and result handling"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (203 commits)
  scsi: core: use blk_mq_run_hw_queues in scsi_kick_queue
  scsi: ufs: remove unnecessary query(DM) UPIU trace
  scsi: qla2xxx: Fix issue reported by static checker for qla2x00_els_dcmd2_sp_done()
  scsi: aacraid: Spelling fix in comment
  scsi: mpt3sas: Fix calltrace observed while running IO & reset
  scsi: aic94xx: fix an error code in aic94xx_init()
  scsi: st: remove redundant pointer STbuffer
  scsi: qla2xxx: Update driver version to 10.00.00.08-k
  scsi: qla2xxx: Migrate NVME N2N handling into state machine
  scsi: qla2xxx: Save frame payload size from ICB
  scsi: qla2xxx: Fix stalled relogin
  scsi: qla2xxx: Fix race between switch cmd completion and timeout
  scsi: qla2xxx: Fix Management Server NPort handle reservation logic
  scsi: qla2xxx: Flush mailbox commands on chip reset
  scsi: qla2xxx: Fix unintended Logout
  scsi: qla2xxx: Fix session state stuck in Get Port DB
  scsi: qla2xxx: Fix redundant fc_rport registration
  scsi: qla2xxx: Silent erroneous message
  scsi: qla2xxx: Prevent sysfs access when chip is down
  scsi: qla2xxx: Add longer window for chip reset
  ...
2018-08-15 22:06:26 -07:00
Bart Van Assche 2afc9166f7 scsi: sysfs: Introduce sysfs_{un,}break_active_protection()
Introduce these two functions and export them such that the next patch
can add calls to these functions from the SCSI core.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2018-08-02 15:53:15 -04:00
Tyler Hicks d175339027 sysfs: Fix regression when adding a file to an existing group
Commit 5f81880d52 ("sysfs, kobject: allow creating kobject belonging
to arbitrary users") incorrectly changed the argument passed as the
parent parameter when calling sysfs_add_file_mode_ns(). This caused some
sysfs attribute files to not be added correctly to certain groups.

Fixes: 5f81880d52 ("sysfs, kobject: allow creating kobject belonging to arbitrary users")
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Reported-by: Heiner Kallweit <hkallweit1@gmail.com>
Tested-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-29 13:11:28 -07:00
Dmitry Torokhov 5f81880d52 sysfs, kobject: allow creating kobject belonging to arbitrary users
Normally kobjects and their sysfs representation belong to global root,
however it is not necessarily the case for objects in separate namespaces.
For example, objects in separate network namespace logically belong to the
container's root and not global root.

This change lays groundwork for allowing network namespace objects
ownership to be transferred to container's root user by defining
get_ownership() callback in ktype structure and using it in sysfs code to
retrieve desired uid/gid when creating sysfs objects for given kobject.

Co-Developed-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-20 23:44:35 -07:00
Dmitry Torokhov 488dee96bb kernfs: allow creating kernfs objects with arbitrary uid/gid
This change allows creating kernfs files and directories with arbitrary
uid/gid instead of always using GLOBAL_ROOT_UID/GID by extending
kernfs_create_dir_ns() and kernfs_create_file_ns() with uid/gid arguments.
The "simple" kernfs_create_file() and kernfs_create_dir() are left alone
and always create objects belonging to the global root.

When creating symlinks ownership (uid/gid) is taken from the target kernfs
object.

Co-Developed-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-20 23:44:35 -07:00
Linus Torvalds ab486bc9a5 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk
Pull printk updates from Petr Mladek:

 - Add a console_msg_format command line option:

     The value "default" keeps the old "[time stamp] text\n" format. The
     value "syslog" allows to see the syslog-like "<log
     level>[timestamp] text" format.

     This feature was requested by people doing regression tests, for
     example, 0day robot. They want to have both filtered and full logs
     at hands.

 - Reduce the risk of softlockup:

     Pass the console owner in a busy loop.

     This is a new approach to the old problem. It was first proposed by
     Steven Rostedt on Kernel Summit 2017. It marks a context in which
     the console_lock owner calls console drivers and could not sleep.
     On the other side, printk() callers could detect this state and use
     a busy wait instead of a simple console_trylock(). Finally, the
     console_lock owner checks if there is a busy waiter at the end of
     the special context and eventually passes the console_lock to the
     waiter.

     The hand-off works surprisingly well and helps in many situations.
     Well, there is still a possibility of the softlockup, for example,
     when the flood of messages stops and the last owner still has too
     much to flush.

     There is increasing number of people having problems with
     printk-related softlockups. We might eventually need to get better
     solution. Anyway, this looks like a good start and promising
     direction.

 - Do not allow to schedule in console_unlock() called from printk():

     This reverts an older controversial commit. The reschedule helped
     to avoid softlockups. But it also slowed down the console output.
     This patch is obsoleted by the new console waiter logic described
     above. In fact, the reschedule made the hand-off less effective.

 - Deprecate "%pf" and "%pF" format specifier:

     It was needed on ia64, ppc64 and parisc64 to dereference function
     descriptors and show the real function address. It is done
     transparently by "%ps" and "pS" format specifier now.

     Sergey Senozhatsky found that all the function descriptors were in
     a special elf section and could be easily detected.

 - Remove printk_symbol() API:

     It has been obsoleted by "%pS" format specifier, and this change
     helped to remove few continuous lines and a less intuitive old API.

 - Remove redundant memsets:

     Sergey removed unnecessary memset when processing printk.devkmsg
     command line option.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk: (27 commits)
  printk: drop redundant devkmsg_log_str memsets
  printk: Never set console_may_schedule in console_trylock()
  printk: Hide console waiter logic into helpers
  printk: Add console owner and waiter logic to load balance console writes
  kallsyms: remove print_symbol() function
  checkpatch: add pF/pf deprecation warning
  symbol lookup: introduce dereference_symbol_descriptor()
  parisc64: Add .opd based function descriptor dereference
  powerpc64: Add .opd based function descriptor dereference
  ia64: Add .opd based function descriptor dereference
  sections: split dereference_function_descriptor()
  openrisc: Fix conflicting types for _exext and _stext
  lib: do not use print_symbol()
  irq debug: do not use print_symbol()
  sysfs: do not use print_symbol()
  drivers: do not use print_symbol()
  x86: do not use print_symbol()
  unicore32: do not use print_symbol()
  sh: do not use print_symbol()
  mn10300: do not use print_symbol()
  ...
2018-02-01 13:36:15 -08:00
Greg Kroah-Hartman 619daeeeb8 sysfs: use SPDX identifiers
Move the license "mark" of the sysfs files to be in SPDX form, instead
of the custom text that it currently is in.  This is in a quest to get
rid of the 700+ different ways we say "GPLv2" in the kernel tree.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-01-23 10:19:10 +01:00
Sergey Senozhatsky 9e6d35ff0a sysfs: do not use print_symbol()
print_symbol() is a very old API that has been obsoleted by %pS format
specifier in a normal printk() call.

Replace print_symbol() with a direct printk("%pS") call.

Link: http://lkml.kernel.org/r/20171211125025.2270-11-sergey.senozhatsky@gmail.com
To: Andrew Morton <akpm@linux-foundation.org>
To: Russell King <linux@armlinux.org.uk>
To: Catalin Marinas <catalin.marinas@arm.com>
To: Mark Salter <msalter@redhat.com>
To: Tony Luck <tony.luck@intel.com>
To: David Howells <dhowells@redhat.com>
To: Yoshinori Sato <ysato@users.sourceforge.jp>
To: Guan Xuetao <gxt@mprc.pku.edu.cn>
To: Borislav Petkov <bp@alien8.de>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>
To: Vineet Gupta <vgupta@synopsys.com>
To: Fengguang Wu <fengguang.wu@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-am33-list@redhat.com
Cc: linux-sh@vger.kernel.org
Cc: linux-edac@vger.kernel.org
Cc: x86@kernel.org
Cc: linux-snps-arc@lists.infradead.org
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
[pmladek@suse.com: updated commit message]
Signed-off-by: Petr Mladek <pmladek@suse.com>
2018-01-05 15:23:59 +01:00
NeilBrown c8a139d001 sysfs: be careful of error returns from ops->show()
ops->show() can return a negative error code.
Commit 65da3484d9 ("sysfs: correctly handle short reads on PREALLOC attrs.")
(in v4.4) caused this to be stored in an unsigned 'size_t' variable, so errors
would look like large numbers.
As a result, if an error is returned, sysfs_kf_read() will return the
value of 'count', typically 4096.

Commit 17d0774f80 ("sysfs: correctly handle read offset on PREALLOC attrs")
(in v4.8) extended this error to use the unsigned large 'len' as a size for
memmove().
Consequently, if ->show returns an error, then the first read() on the
sysfs file will return 4096 and could return uninitialized memory to
user-space.
If the application performs a subsequent read, this will trigger a memmove()
with extremely large count, and is likely to crash the machine is bizarre ways.

This bug can currently only be triggered by reading from an md
sysfs attribute declared with __ATTR_PREALLOC() during the
brief period between when mddev_put() deletes an mddev from
the ->all_mddevs list, and when mddev_delayed_delete() - which is
scheduled on a workqueue - completes.
Before this, an error won't be returned by the ->show()
After this, the ->show() won't be called.

I can reproduce it reliably only by putting delay like
	usleep_range(500000,700000);
early in mddev_delayed_delete(). Then after creating an
md device md0 run
  echo clear > /sys/block/md0/md/array_state; cat /sys/block/md0/md/array_state

The bug can be triggered without the usleep.

Fixes: 65da3484d9 ("sysfs: correctly handle short reads on PREALLOC attrs.")
Fixes: 17d0774f80 ("sysfs: correctly handle read offset on PREALLOC attrs")
Cc: stable@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-04-08 17:33:32 +02:00
Konstantin Khlebnikov 17d0774f80 sysfs: correctly handle read offset on PREALLOC attrs
Attributes declared with __ATTR_PREALLOC use sysfs_kf_read() which returns
zero bytes for non-zero offset. This breaks script checkarray in mdadm tool
in debian where /bin/sh is 'dash' because its builtin 'read' reads only one
byte at a time. Script gets 'i' instead of 'idle' when reads current action
from /sys/block/$dev/md/sync_action and as a result does nothing.

This patch adds trivial implementation of partial read: generate whole
string and move required part into buffer head.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Fixes: 4ef67a8c95 ("sysfs/kernfs: make read requests on pre-alloc files use the buffer.")
Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=787950
Cc: Stable <stable@vger.kernel.org> # v3.19+
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-08-31 15:14:44 +02:00
NeilBrown 65da3484d9 sysfs: correctly handle short reads on PREALLOC attrs.
attributes declared with __ATTR_PREALLOC use sysfs_kf_read()
which ignores the 'count' arg.
So a 1-byte read request can return more bytes than that.

This is seen with the 'dash' shell when 'read' is used on
some 'md' sysfs attributes.

So only return the 'min' of count and the attribute length.

Signed-off-by: NeilBrown <neilb@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-10-04 19:42:22 +01:00
Vladimir Zapolskiy eaa5cd9263 fs: sysfs: don't pass count == 0 to bin file readers
If count == 0 bytes are requested by a reader, sysfs_kf_bin_read()
deliberately returns 0 without passing a potentially harmful value to
some externally defined underlying battr->read() function.

However in case of (pos == size && count) the next clause always sets
count to 0 and this value is handed over to battr->read().

The change intends to make obsolete (and remove later) a redundant
sanity check in battr->read(), if it is present, or add more
protection to struct bin_attribute users, who does not care about
input arguments.

Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-06-01 10:17:17 +09:00
Tejun Heo dfeb0750b6 kernfs: remove KERNFS_STATIC_NAME
When a new kernfs node is created, KERNFS_STATIC_NAME is used to avoid
making a separate copy of its name.  It's currently only used for sysfs
attributes whose filenames are required to stay accessible and unchanged.
There are rare exceptions where these names are allocated and formatted
dynamically but for the vast majority of cases they're consts in the
rodata section.

Now that kernfs is converted to use kstrdup_const() and kfree_const(),
there's little point in keeping KERNFS_STATIC_NAME around.  Remove it.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13 21:21:36 -08:00
NeilBrown 4ef67a8c95 sysfs/kernfs: make read requests on pre-alloc files use the buffer.
To match the previous patch which used the pre-alloc buffer for
writes, this patch causes reads to use the same buffer.
This is not strictly necessary as the current seq_read() will allocate
on first read, so user-space can trigger the required pre-alloc.  But
consistency is valuable.

The read function is somewhat simpler than seq_read() and, for example,
does not support reading from an offset into the file: reads must be
at the start of the file.

As seq_read() does not use the prealloc buffer, ->seq_show is
incompatible with ->prealloc and caused an EINVAL return from open().
sysfs code which calls into kernfs always chooses the correct function.

As the buffer is shared with writes and other reads, the mutex is
extended to cover the copy_to_user.

Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-07 10:54:38 -08:00
NeilBrown 2b75869bba sysfs/kernfs: allow attributes to request write buffer be pre-allocated.
md/raid allows metadata management to be performed in user-space.
A various times, particularly on device failure, the metadata needs
to be updated before further writes can be permitted.
This means that the user-space program which updates metadata much
not block on writeout, and so must not allocate memory.

mlockall(MCL_CURRENT|MCL_FUTURE) and pre-allocation can avoid all
memory allocation issues for user-memory, but that does not help
kernel memory.
Several kernel objects can be pre-allocated.  e.g. files opened before
any writes to the array are permitted.
However some kernel allocation happens in places that cannot be
pre-allocated.
In particular, writes to sysfs files (to tell md that it can now
allow writes to the array) allocate a buffer using GFP_KERNEL.

This patch allows attributes to be marked as "PREALLOC".  In that case
the maximal buffer is allocated when the file is opened, and then used
on each write instead of allocating a new buffer.

As the same buffer is now shared for all writes on the same file
description, the mutex is extended to cover full use of the buffer
including the copy_from_user().

The new __ATTR_PREALLOC() 'or's a new flag in to the 'mode', which is
inspected by sysfs_add_file_mode_ns() to determine if the file should be
marked as requiring prealloc.

Despite the comment, we *do* use ->seq_show together with ->prealloc
in this patch.  The next patch fixes that.

Signed-off-by: NeilBrown  <neilb@suse.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-07 10:53:25 -08:00
Vladimir Zapolskiy 0936896056 fs: sysfs: return EGBIG on write if offset is larger than file size
According to the user expectations common utilities like dd or sh
redirection operator > should work correctly over binary files from
sysfs. At the moment doing excessive write can not be completed:

  write(1, "\0\0\0\0\0\0\0\0", 8)         = 4
  write(1, "\0\0\0\0", 4)                 = 0
  write(1, "\0\0\0\0", 4)                 = 0
  write(1, "\0\0\0\0", 4)                 = 0
  ...

Fix the problem by returning EFBIG described in man 2 write.

Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-07 10:52:20 -08:00
Tejun Heo f5c16f29bf sysfs: make sure read buffer is zeroed
13c589d5b0 ("sysfs: use seq_file when reading regular files")
switched sysfs from custom read implementation to seq_file to enable
later transition to kernfs.  After the change, the buffer passed to
->show() is acquired through seq_get_buf(); unfortunately, this
introduces a subtle behavior change.  Before the commit, the buffer
passed to ->show() was always zero as it was allocated using
get_zeroed_page().  Because seq_file doesn't clear buffers on
allocation and neither does seq_get_buf(), after the commit, depending
on the behavior of ->show(), we may end up exposing uninitialized data
to userland thus possibly altering userland visible behavior and
leaking information.

Fix it by explicitly clearing the buffer.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Ron <ron@debian.org>
Fixes: 13c589d5b0 ("sysfs: use seq_file when reading regular files")
Cc: stable <stable@vger.kernel.org> # 3.13+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-05-20 10:15:53 +09:00
Tejun Heo 33ac1257ff sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()
All device_schedule_callback_owner() users are converted to use
device_remove_file_self().  Remove now unused
{sysfs|device}_schedule_callback_owner().

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-16 11:56:33 -07:00
Greg Kroah-Hartman 72099304ee Revert "sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()"
This reverts commit d1ba277e79.

As reported by Stephen, this patch breaks linux-next as a ppc patch
suddenly (after 2 years) started using this old api call.  So revert it
for now, it will go away in 3.15-rc2 when we can change the PPC call to
the new api.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tejun Heo <tj@kernel.org>
Cc: Stewart Smith <stewart@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-03-25 20:54:57 -07:00
Tejun Heo ce8b04aa6c sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()
All device_schedule_callback_owner() users are converted to use
device_remove_file_self().  Remove now unused
{sysfs|device}_schedule_callback_owner().

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07 15:42:41 -08:00
Tejun Heo 6b0afc2a21 kernfs, sysfs, driver-core: implement kernfs_remove_self() and its wrappers
Sometimes it's necessary to implement a node which wants to delete
nodes including itself.  This isn't straightforward because of kernfs
active reference.  While a file operation is in progress, an active
reference is held and kernfs_remove() waits for all such references to
drain before completing.  For a self-deleting node, this is a deadlock
as kernfs_remove() ends up waiting for an active reference that itself
is sitting on top of.

This currently is worked around in the sysfs layer using
sysfs_schedule_callback() which makes such removals asynchronous.
While it works, it's rather cumbersome and inherently breaks
synchronicity of the operation - the file operation which triggered
the operation may complete before the removal is finished (or even
started) and the removal may fail asynchronously.  If a removal
operation is immmediately followed by another operation which expects
the specific name to be available (e.g. removal followed by rename
onto the same name), there's no way to make the latter operation
reliable.

The thing is there's no inherent reason for this to be asynchrnous.
All that's necessary to do this synchronous is a dedicated operation
which drops its own active ref and deactivates self.  This patch
implements kernfs_remove_self() and its wrappers in sysfs and driver
core.  kernfs_remove_self() is to be called from one of the file
operations, drops the active ref the task is holding, removes the self
node, and restores active ref to the dead node so that the ref is
balanced afterwards.  __kernfs_remove() is updated so that it takes an
early exit if the target node is already fully removed so that the
active ref restored by kernfs_remove_self() after removal doesn't
confuse the deactivation path.

This makes implementing self-deleting nodes very easy.  The normal
removal path doesn't even need to be changed to use
kernfs_remove_self() for the self-deleting node.  The method can
invoke kernfs_remove_self() on itself before proceeding the normal
removal path.  kernfs_remove() invoked on the node by the normal
deletion path will simply be ignored.

This will replace sysfs_schedule_callback().  A subtle feature of
sysfs_schedule_callback() is that it collapses multiple invocations -
even if multiple removals are triggered, the removal callback is run
only once.  An equivalent effect can be achieved by testing the return
value of kernfs_remove_self() - only the one which gets %true return
value should proceed with actual deletion.  All other instances of
kernfs_remove_self() will wait till the enclosing kernfs operation
which invoked the winning instance of kernfs_remove_self() finishes
and then return %false.  This trivially makes all users of
kernfs_remove_self() automatically show correct synchronous behavior
even when there are multiple concurrent operations - all "echo 1 >
delete" instances will finish only after the whole operation is
completed by one of the instances.

Note that manipulation of active ref is implemented in separate public
functions - kernfs_[un]break_active_protection().
kernfs_remove_self() is the only user at the moment but this will be
used to cater to more complex cases.

v2: For !CONFIG_SYSFS, dummy version kernfs_remove_self() was missing
    and sysfs_remove_file_self() had incorrect return type.  Fix it.
    Reported by kbuild test bot.

v3: kernfs_[un]break_active_protection() separated out from
    kernfs_remove_self() and exposed as public API.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07 15:42:41 -08:00
Greg Kroah-Hartman a9f138b0e5 Revert "kernfs, sysfs, driver-core: implement kernfs_remove_self() and its wrappers"
This reverts commit 1ae06819c7.

Tejun writes:
        I'm sorry but can you please revert the whole series?
        get_active() waiting while a node is deactivated has potential
        to lead to deadlock and that deactivate/reactivate interface is
        something fundamentally flawed and that cgroup will have to work
        with the remove_self() like everybody else.  IOW, I think the
        first posting was correct.

Cc: Tejun Heo <tj@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-13 14:05:13 -08:00
Greg Kroah-Hartman a30f82b7eb Revert "sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()"
This reverts commit d1ba277e79.

Tejun writes:
        I'm sorry but can you please revert the whole series?
        get_active() waiting while a node is deactivated has potential
        to lead to deadlock and that deactivate/reactivate interface is
        something fundamentally flawed and that cgroup will have to work
        with the remove_self() like everybody else.  IOW, I think the
        first posting was correct.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-13 13:51:36 -08:00
Tejun Heo d1ba277e79 sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()
All device_schedule_callback_owner() users are converted to use
device_remove_file_self().  Remove now unused
{sysfs|device}_schedule_callback_owner().

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-10 16:03:19 -08:00
Tejun Heo 1ae06819c7 kernfs, sysfs, driver-core: implement kernfs_remove_self() and its wrappers
Sometimes it's necessary to implement a node which wants to delete
nodes including itself.  This isn't straightforward because of kernfs
active reference.  While a file operation is in progress, an active
reference is held and kernfs_remove() waits for all such references to
drain before completing.  For a self-deleting node, this is a deadlock
as kernfs_remove() ends up waiting for an active reference that itself
is sitting on top of.

This currently is worked around in the sysfs layer using
sysfs_schedule_callback() which makes such removals asynchronous.
While it works, it's rather cumbersome and inherently breaks
synchronicity of the operation - the file operation which triggered
the operation may complete before the removal is finished (or even
started) and the removal may fail asynchronously.  If a removal
operation is immmediately followed by another operation which expects
the specific name to be available (e.g. removal followed by rename
onto the same name), there's no way to make the latter operation
reliable.

The thing is there's no inherent reason for this to be asynchrnous.
All that's necessary to do this synchronous is a dedicated operation
which drops its own active ref and deactivates self.  This patch
implements kernfs_remove_self() and its wrappers in sysfs and driver
core.  kernfs_remove_self() is to be called from one of the file
operations, drops the active ref and deactivates using
__kernfs_deactivate_self(), removes the self node, and restores active
ref to the dead node using __kernfs_reactivate_self() so that the ref
is balanced afterwards.  __kernfs_remove() is updated so that it takes
an early exit if the target node is already fully removed so that the
active ref restored by kernfs_remove_self() after removal doesn't
confuse the deactivation path.

This makes implementing self-deleting nodes very easy.  The normal
removal path doesn't even need to be changed to use
kernfs_remove_self() for the self-deleting node.  The method can
invoke kernfs_remove_self() on itself before proceeding the normal
removal path.  kernfs_remove() invoked on the node by the normal
deletion path will simply be ignored.

This will replace sysfs_schedule_callback().  A subtle feature of
sysfs_schedule_callback() is that it collapses multiple invocations -
even if multiple removals are triggered, the removal callback is run
only once.  An equivalent effect can be achieved by testing the return
value of kernfs_remove_self() - only the one which gets %true return
value should proceed with actual deletion.  All other instances of
kernfs_remove_self() will wait till the enclosing kernfs operation
which invoked the winning instance of kernfs_remove_self() finishes
and then return %false.  This trivially makes all users of
kernfs_remove_self() automatically show correct synchronous behavior
even when there are multiple concurrent operations - all "echo 1 >
delete" instances will finish only after the whole operation is
completed by one of the instances.

v2: For !CONFIG_SYSFS, dummy version kernfs_remove_self() was missing
    and sysfs_remove_file_self() had incorrect return type.  Fix it.
    Reported by kbuild test bot.

v3: Updated to use __kernfs_{de|re}activate_self().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-10 14:01:05 -08:00
Tejun Heo 2063d608f5 kernfs: mark static names with KERNFS_STATIC_NAME
Because sysfs used struct attribute which are supposed to stay
constant, sysfs didn't copy names when creating regular files.  The
specified string for name was supposed to stay constant.  Such
distinction isn't inherent for kernfs.  kernfs_create_file[_ns]()
should be able to take the same @name as kernfs_create_dir[_ns]()

As there can be huge number of sysfs attributes, we still want to be
able to use static names for sysfs attributes.  This patch renames
kernfs_create_file_ns_key() to __kernfs_create_file() and adds
@name_is_static parameter so that the caller can explicitly indicate
that @name can be used without copying.  kernfs is updated to use
KERNFS_STATIC_NAME to distinguish static and copied names.

This patch doesn't introduce any behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-17 08:59:15 -08:00
Tejun Heo df23fc39bc kernfs: s/sysfs/kernfs/ in constants
kernfs has just been separated out from sysfs and we're already in
full conflict mode.  Nothing can make the situation any worse.  Let's
take the chance to name things properly.

This patch performs the following renames.

* s/SYSFS_DIR/KERNFS_DIR/
* s/SYSFS_KOBJ_ATTR/KERNFS_FILE/
* s/SYSFS_KOBJ_LINK/KERNFS_LINK/
* s/SYSFS_{TYPE_FLAGS}/KERNFS_{TYPE_FLAGS}/
* s/SYSFS_FLAG_{FLAG}/KERNFS_{FLAG}/
* s/sysfs_type()/kernfs_type()/
* s/SD_DEACTIVATED_BIAS/KN_DEACTIVATED_BIAS/

This patch is strictly rename only and doesn't introduce any
functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-11 17:39:20 -08:00
Tejun Heo c525aaddc3 kernfs: s/sysfs/kernfs/ in various data structures
kernfs has just been separated out from sysfs and we're already in
full conflict mode.  Nothing can make the situation any worse.  Let's
take the chance to name things properly.

This patch performs the following renames.

* s/sysfs_open_dirent/kernfs_open_node/
* s/sysfs_open_file/kernfs_open_file/
* s/sysfs_inode_attrs/kernfs_iattrs/
* s/sysfs_addrm_cxt/kernfs_addrm_cxt/
* s/sysfs_super_info/kernfs_super_info/
* s/sysfs_info()/kernfs_info()/
* s/sysfs_open_dirent_lock/kernfs_open_node_lock/
* s/sysfs_open_file_mutex/kernfs_open_file_mutex/
* s/sysfs_of()/kernfs_of()/

This patch is strictly rename only and doesn't introduce any
functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-11 17:39:20 -08:00