user/sven/linux.git/include/linux/sysfs.h, branch v6.13.1

sysfs: attribute_group: allow registration of const bin_attribute

2024-11-15T18:29:16Z

To be able to constify instances of struct bin_attribute it has to be possible to add them to string attribute_group. The current type of the bin_attrs member however is not compatible with that. Introduce a union that allows registration of both const and non-const attributes to enable a piecewise transition. As both union member types are compatible no logic needs to be adapted. Technically it is now possible register a const struct bin_attribute and receive it as mutable pointer in the callbacks. This is a soundness issue. But this same soundness issue already exists today in sysfs_create_bin_file(). Also the struct definition and callback implementation are always closely linked and are meant to be moved to const in lockstep. Signed-off-by: Thomas Weißschuh Link: https://lore.kernel.org/r/20241115-b4-sysfs-const-bin_attr-group-v1-1-2c9bb12dfc48@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: bin_attribute: add const read/write callback variants

2024-11-05T13:00:28Z

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 Acked-by: Krzysztof Wilczyński Link: https://lore.kernel.org/r/20241103-sysfs-const-bin_attr-v2-9-71110628844c@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: implement all BIN_ATTR_* macros in terms of __BIN_ATTR()

2024-11-05T13:00:28Z

The preparations for the upcoming constification of struct bin_attribute requires some logic in the structure definition macros. To avoid duplication of that logic in multiple macros, reimplement all other macros in terms of __BIN_ATTR(). Signed-off-by: Thomas Weißschuh Acked-by: Krzysztof Wilczyński Link: https://lore.kernel.org/r/20241103-sysfs-const-bin_attr-v2-8-71110628844c@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: treewide: constify attribute callback of bin_attribute::llseek()

2024-11-05T13:00:28Z

The llseek() callbacks should not modify the struct bin_attribute passed as argument. Enforce this by marking the argument as const. As there are not many callback implementers perform this change throughout the tree at once. Signed-off-by: Thomas Weißschuh Acked-by: Krzysztof Wilczyński Link: https://lore.kernel.org/r/20241103-sysfs-const-bin_attr-v2-7-71110628844c@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: treewide: constify attribute callback of bin_attribute::mmap()

2024-11-05T13:00:28Z

The mmap() callbacks should not modify the struct bin_attribute passed as argument. Enforce this by marking the argument as const. As there are not many callback implementers perform this change throughout the tree at once. Signed-off-by: Thomas Weißschuh Acked-by: Andrew Donnellan # ocxl Acked-by: Krzysztof Wilczyński Link: https://lore.kernel.org/r/20241103-sysfs-const-bin_attr-v2-6-71110628844c@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: treewide: constify attribute callback of bin_is_visible()

2024-11-05T13:00:28Z

The is_bin_visible() callbacks should not modify the struct bin_attribute passed as argument. Enforce this by marking the argument as const. As there are not many callback implementers perform this change throughout the tree at once. Signed-off-by: Thomas Weißschuh Acked-by: Martin K. Petersen Acked-by: Jason Gunthorpe Acked-by: Ira Weiny Acked-by: Krzysztof Wilczyński Link: https://lore.kernel.org/r/20241103-sysfs-const-bin_attr-v2-5-71110628844c@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: introduce callback attribute_group::bin_size

2024-11-05T13:00:28Z

Several drivers need to dynamically calculate the size of an binary attribute. Currently this is done by assigning attr->size from the is_bin_visible() callback. This has drawbacks: * It is not documented. * A single attribute can be instantiated multiple times, overwriting the shared size field. * It prevents the structure to be moved to read-only memory. Introduce a new dedicated callback to calculate the size of the attribute. Signed-off-by: Thomas Weißschuh Acked-by: Krzysztof Wilczyński Link: https://lore.kernel.org/r/20241103-sysfs-const-bin_attr-v2-2-71110628844c@weissschuh.net Signed-off-by: Greg Kroah-Hartman

sysfs: Unbreak the build around sysfs_bin_attr_simple_read()

2024-06-04T13:56:45Z

Günter reports build breakage for m68k "m5208evb_defconfig" plus CONFIG_BLK_DEV_INITRD=y caused by commit 66bc1a173328 ("treewide: Use sysfs_bin_attr_simple_read() helper"). The defconfig disables CONFIG_SYSFS, so sysfs_bin_attr_simple_read() is not compiled into the kernel. But init/initramfs.c references that function in the initializer of a struct bin_attribute. Add an empty static inline to avoid the build breakage. Fixes: 66bc1a173328 ("treewide: Use sysfs_bin_attr_simple_read() helper") Reported-by: Guenter Roeck Closes: https://lore.kernel.org/r/e12b0027-b199-4de7-b83d-668171447ccc@roeck-us.net Signed-off-by: Lukas Wunner Tested-by: Guenter Roeck Reviewed-by: Rafael J. Wysocki Link: https://lore.kernel.org/r/05f4290439a58730738a15b0c99cd8576c4aa0d9.1716461752.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman

sysfs: Add sysfs_bin_attr_simple_read() helper

2024-04-11T14:02:25Z

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 Reviewed-by: Greg Kroah-Hartman Acked-by: Rafael J. Wysocki Acked-by: Ard Biesheuvel Link: https://lore.kernel.org/r/5ed62b197a442ec6db53d8746d9d806dd0576e2d.1712410202.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman

sysfs: Introduce DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE()

2024-02-23T06:34:26Z

One of the first users of DEFINE_SYSFS_GROUP_VISIBLE() did this: static umode_t dp0_attr_visible(struct kobject *kobj, struct attribute *attr, int n) { struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj)); if (slave->prop.dp0_prop) return attr->mode; return 0; } static bool dp0_group_visible(struct kobject *kobj) { struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj)); if (slave->prop.dp0_prop) return true; return false; } DEFINE_SYSFS_GROUP_VISIBLE(dp0); ...i.e. the _group_visible() helper is identical to the _attr_visible() helper. Use the "simple" helper to reduce that to: static bool dp0_group_visible(struct kobject *kobj) { struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj)); if (slave->prop.dp0_prop) return true; return false; } DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE(dp0); Remove the need to specify per attribute visibility if the goal is to hide the entire group. Signed-off-by: Dan Williams Link: https://lore.kernel.org/r/170863446625.1479840.10593839479268727913.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman