linux/fs/char_dev.c, branch v5.3

chardev: set variable ret to -EBUSY before checking minor range overlap

2019-05-24T18:50:36Z

When allocating dynamic major, the minor range overlap check in __register_chrdev_region() will not fail, so actually there is no real case to passing non negative error code to caller. However, set variable ret to -EBUSY before checking minor range overlap will avoid false-positive warning from code analyzing tool(like Smatch) and also make the code more easy to understand. Suggested-by: Dan Carpenter Signed-off-by: Chengguang Xu Signed-off-by: Greg Kroah-Hartman

chardev: update comment based on the code

2019-04-02T15:49:58Z

The function comment of __register_chrdev_region() is out of date, so update it based on the code. Signed-off-by: Chengguang Xu Signed-off-by: Greg Kroah-Hartman

chardev: code cleanup for __register_chrdev_region()

2019-04-02T15:49:58Z

It's just code cleanup, not functional change. Signed-off-by: Chengguang Xu Signed-off-by: Greg Kroah-Hartman

chardev: add a check for given minor range

2019-04-02T15:49:58Z

register_chrdev_region() carefully checks minor range before calling __register_chrdev_region() but there is another path from alloc_chrdev_region() which does not check the range properly. So add a check for given minor range in __register_chrdev_region(). Signed-off-by: Chengguang Xu Signed-off-by: Greg Kroah-Hartman

chardev: add additional check for minor range overlap

2019-04-02T15:49:58Z

Current overlap checking cannot correctly handle a case which is baseminor < existing baseminor && baseminor + minorct > existing baseminor + minorct. Signed-off-by: Chengguang Xu Signed-off-by: Greg Kroah-Hartman

block, char_dev: Use correct format specifier for unsigned ints

2018-03-15T16:59:24Z

register_blkdev() and __register_chrdev_region() treat the major number as an unsigned int. So print it the same way to avoid absurd error statements such as: "... major requested (-1) is greater than the maximum (511) ..." (and also fix off-by-one bugs in the error prints). While at it, also update the comment describing register_blkdev(). Signed-off-by: Srivatsa S. Bhat Reviewed-by: Logan Gunthorpe Signed-off-by: Greg Kroah-Hartman

char_dev: Fix off-by-one bugs in find_dynamic_major()

2018-03-15T16:59:24Z

CHRDEV_MAJOR_DYN_END and CHRDEV_MAJOR_DYN_EXT_END are valid major numbers. So fix the loop iteration to include them in the search for free major numbers. While at it, also remove a redundant if condition ("cd->major != i"), as it will never be true. Signed-off-by: Srivatsa S. Bhat Reviewed-by: Logan Gunthorpe Signed-off-by: Greg Kroah-Hartman

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02T10:10:55Z

Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart Reviewed-by: Philippe Ombredanne Reviewed-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

char_dev: order /proc/devices by major number

2017-07-17T13:28:50Z

Presently, the order of the char devices listed in /proc/devices is not entirely sequential. If a char device has a major number greater than CHRDEV_MAJOR_HASH_SIZE (255), it will be ordered as if its major were module 255. For example, 511 appears after 1. This patch cleans that up and prints each major number in the correct order, regardless of where they are stored in the hash table. In order to do this, we introduce CHRDEV_MAJOR_MAX as an artificial limit (chosen to be 511). It will then print all devices in major order number from 0 to the maximum. Signed-off-by: Logan Gunthorpe Cc: Linus Torvalds Cc: Greg Kroah-Hartman Cc: Alan Cox Cc: Arnd Bergmann Cc: Linus Walleij Signed-off-by: Greg Kroah-Hartman

char_dev: extend dynamic allocation of majors into a higher range

2017-07-17T13:09:17Z

We've run into problems with running out of dynamicly assign char device majors particullarly on automated test systems with all-yes-configs. Roughly 40 dynamic assignments can be made with such kernels at this time while space is reserved for only 20. Currently, the kernel only prints a warning when dynamic allocation overflows the reserved region. And when this happens drivers that have fixed assignments can randomly fail depending on the order of initialization of other drivers. Thus, adding a new char device can cause unexpected failures in completely unrelated parts of the kernel. This patch solves the problem by extending dynamic major number allocations down from 511 once the 234-254 region fills up. Fixed majors already exist above 255 so the infrastructure to support high number majors is already in place. The patch reserves an additional 128 major numbers which should hopefully last us a while. Kernels that don't require more than 20 dynamic majors assigned (which is pretty typical) should not be affected by this change. Signed-off-by: Logan Gunthorpe Cc: Linus Torvalds Cc: Alan Cox Cc: Arnd Bergmann Cc: Linus Walleij Link: https://lkml.org/lkml/2017/6/4/107 Signed-off-by: Greg Kroah-Hartman