linux.git/fs/sysfs/file.c, branch v6.13 Linux kernel source tree sysfs: bin_attribute: add const read/write callback variants 2024-11-05T13:00:28+00:00 Thomas Weißschuh linux@weissschuh.net 2024-11-03T17:03:38+00:00 eb2e6c3a8d66ff37b2ee26cd32334ae0e05fd596 To make it possible to put struct bin_attribute into read-only memory, the sysfs core has to stop passing mutable pointers to the read() and write() callbacks. As there are numerous implementors of these callbacks throughout the tree it's not possible to change all of them at once. To enable a step-by-step transition, add new variants of the read() and write() callbacks which differ only in the constness of the struct bin_attribute argument. As most binary attributes are defined through macros, extend these macros to transparently handle both variants of callbacks to minimize the churn during the transition. As soon as all handlers are switch to the const variant, the non-const one can be removed together with the transition machinery. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Acked-by: Krzysztof Wilczyński <kw@linux.com> Link: https://lore.kernel.org/r/20241103-sysfs-const-bin_attr-v2-9-71110628844c@weissschuh.net Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
To make it possible to put struct bin_attribute into read-only memory,
the sysfs core has to stop passing mutable pointers to the read() and
write() callbacks.
As there are numerous implementors of these callbacks throughout the
tree it's not possible to change all of them at once.
To enable a step-by-step transition, add new variants of the read() and
write() callbacks which differ only in the constness of the struct
bin_attribute argument.

As most binary attributes are defined through macros, extend these
macros to transparently handle both variants of callbacks to minimize
the churn during the transition.
As soon as all handlers are switch to the const variant, the non-const
one can be removed together with the transition machinery.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Krzysztof Wilczyński <kw@linux.com>
Link: https://lore.kernel.org/r/20241103-sysfs-const-bin_attr-v2-9-71110628844c@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sysfs: explicitly pass size to sysfs_add_bin_file_mode_ns() 2024-11-05T13:00:28+00:00 Thomas Weißschuh linux@weissschuh.net 2024-11-03T17:03:30+00:00 0afcee132bbc9d7ef9c5bb4da9b6fe014a9afaa9 Upcoming changes to the sysfs core require the size of the created file to be overridable by the caller. Add a parameter to enable this. For now keep using attr->size in all cases. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Acked-by: Krzysztof Wilczyński <kw@linux.com> Link: https://lore.kernel.org/r/20241103-sysfs-const-bin_attr-v2-1-71110628844c@weissschuh.net Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Upcoming changes to the sysfs core require the size of the created file
to be overridable by the caller.
Add a parameter to enable this.
For now keep using attr->size in all cases.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Krzysztof Wilczyński <kw@linux.com>
Link: https://lore.kernel.org/r/20241103-sysfs-const-bin_attr-v2-1-71110628844c@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge 6.9-rc5 into driver-core-next 2024-04-23T11:27:43+00:00 Greg Kroah-Hartman gregkh@linuxfoundation.org 2024-04-23T11:27:43+00:00 e5019b14230a0bc1f6641c9850ae39cfe76ad2aa We want the kernfs fixes in here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
We want the kernfs fixes in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sysfs: Add sysfs_bin_attr_simple_read() helper 2024-04-11T14:02:25+00:00 Lukas Wunner lukas@wunner.de 2024-04-06T13:52:01+00:00 d48c03198a92edf41e89477dab4f602df15165ee 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> 
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>
fs: sysfs: Fix reference leak in sysfs_break_active_protection() 2024-04-11T13:16:48+00:00 Alan Stern stern@rowland.harvard.edu 2024-03-13T21:43:41+00:00 a90bca2228c0646fc29a72689d308e5fe03e6d78 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: 2afc9166f79b ("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> 
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: 2afc9166f79b ("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>
kernfs: sysfs: support custom llseek method for sysfs entries 2023-10-05T11:42:11+00:00 Valentine Sinitsyn valesini@yandex-team.ru 2023-09-25T08:40:12+00:00 0fedefd4c4e33dd24f726b13b5d7c143e2b483be 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 636b21b50152 ("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> 
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 636b21b50152 ("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>
kobject: kobj_type: remove default_attrs 2022-04-05T13:39:19+00:00 Greg Kroah-Hartman gregkh@linuxfoundation.org 2022-01-06T13:31:51+00:00 cdb4f26a63c391317e335e6e683a614358e70aeb 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> 
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>
sysfs: simplify sysfs_kf_seq_show 2021-09-14T15:03:01+00:00 Christoph Hellwig hch@lst.de 2021-09-13T05:41:14+00:00 820879ee1865f7010ec3a949322f643f008c9feb 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> 
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>
sysfs: refactor sysfs_add_file_mode_ns 2021-09-14T15:02:58+00:00 Christoph Hellwig hch@lst.de 2021-09-13T05:41:13+00:00 d1a1a9606e080c9767e229742f5b331b3b551c0c 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> 
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>
sysfs: split out binary attribute handling from sysfs_add_file_mode_ns 2021-09-14T14:59:46+00:00 Christoph Hellwig hch@lst.de 2021-09-13T05:41:12+00:00 5cf3bb0d3a2d0de94f3f551f0e4211068818aabf 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> 
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>