linux-toradex.git/lib/string_helpers.c, branch v5.12-rc6

lib: string_helpers: provide kfree_strarray()

2020-09-30T08:50:30+00:00

There's a common pattern of dynamically allocating an array of char
pointers and then also dynamically allocating each string in this
array. Provide a helper for freeing such a string array with one call.

Signed-off-by: Bartosz Golaszewski 
Reviewed-by: Andy Shevchenko

lib/string_helpers: fix some kerneldoc warnings

2019-07-17T02:23:22+00:00

Due to some sad limitations in how kerneldoc comments are parsed, the
documentation in lib/string_helpers.c generates these warnings:

  lib/string_helpers.c:236: WARNING: Unexpected indentation.
  lib/string_helpers.c:241: WARNING: Block quote ends without a blank line; unexpected unindent.
  lib/string_helpers.c:446: WARNING: Unexpected indentation.
  lib/string_helpers.c:451: WARNING: Block quote ends without a blank line; unexpected unindent.
  lib/string_helpers.c:474: WARNING: Unexpected indentation.

Rework the comments to obtain something like the desired result.

Link: http://lkml.kernel.org/r/20190607110952.409011ba@lwn.net
Signed-off-by: Jonathan Corbet 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

nfsd: escape high characters in binary data

2019-07-03T21:52:50+00:00

I'm exposing some information about NFS clients in pseudofiles.  I
expect to eventually have simple tools to help read those pseudofiles.

But it's also helpful if the raw files are human-readable to the extent
possible.  It aids debugging and makes them usable on systems that don't
have the latest nfs-utils.

A minor challenge there is opaque client-generated protocol objects like
state owners and client identifiers.  Some clients generate those to
include handy information in plain ascii.  But they may also include
arbitrary byte sequences.

I think the simplest approach is to limit to isprint(c) && isascii(c)
and escape everything else.

That means you can just cat the file and get something that looks OK.
Also, I'm trying to keep these files legal YAML, which requires them to
UTF-8, and this is a simple way to guarantee that.

Acked-by: Kees Cook 
Signed-off-by: J. Bruce Fields

treewide: Add SPDX license identifier for missed files

2019-05-21T08:50:45+00:00

Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

mm: treewide: remove GFP_TEMPORARY allocation flag

2017-09-14T01:53:16+00:00

GFP_TEMPORARY was introduced by commit e12ba74d8ff3 ("Group short-lived
and reclaimable kernel allocations") along with __GFP_RECLAIMABLE.  It's
primary motivation was to allow users to tell that an allocation is
short lived and so the allocator can try to place such allocations close
together and prevent long term fragmentation.  As much as this sounds
like a reasonable semantic it becomes much less clear when to use the
highlevel GFP_TEMPORARY allocation flag.  How long is temporary? Can the
context holding that memory sleep? Can it take locks? It seems there is
no good answer for those questions.

The current implementation of GFP_TEMPORARY is basically GFP_KERNEL |
__GFP_RECLAIMABLE which in itself is tricky because basically none of
the existing caller provide a way to reclaim the allocated memory.  So
this is rather misleading and hard to evaluate for any benefits.

I have checked some random users and none of them has added the flag
with a specific justification.  I suspect most of them just copied from
other existing users and others just thought it might be a good idea to
use without any measuring.  This suggests that GFP_TEMPORARY just
motivates for cargo cult usage without any reasoning.

I believe that our gfp flags are quite complex already and especially
those with highlevel semantic should be clearly defined to prevent from
confusion and abuse.  Therefore I propose dropping GFP_TEMPORARY and
replace all existing users to simply use GFP_KERNEL.  Please note that
SLAB users with shrinkers will still get __GFP_RECLAIMABLE heuristic and
so they will be placed properly for memory fragmentation prevention.

I can see reasons we might want some gfp flag to reflect shorterm
allocations but I propose starting from a clear semantic definition and
only then add users with proper justification.

This was been brought up before LSF this year by Matthew [1] and it
turned out that GFP_TEMPORARY really doesn't have a clear semantic.  It
seems to be a heuristic without any measured advantage for most (if not
all) its current users.  The follow up discussion has revealed that
opinions on what might be temporary allocation differ a lot between
developers.  So rather than trying to tweak existing users into a
semantic which they haven't expected I propose to simply remove the flag
and start from scratch if we really need a semantic for short term
allocations.

[1] http://lkml.kernel.org/r/20170118054945.GD18349@bombadil.infradead.org

[akpm@linux-foundation.org: fix typo]
[akpm@linux-foundation.org: coding-style fixes]
[sfr@canb.auug.org.au: drm/i915: fix up]
  Link: http://lkml.kernel.org/r/20170816144703.378d4f4d@canb.auug.org.au
Link: http://lkml.kernel.org/r/20170728091904.14627-1-mhocko@kernel.org
Signed-off-by: Michal Hocko 
Signed-off-by: Stephen Rothwell 
Acked-by: Mel Gorman 
Acked-by: Vlastimil Babka 
Cc: Matthew Wilcox 
Cc: Neil Brown 
Cc: "Theodore Ts'o" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

string_helpers: add kstrdup_quotable_file

2016-04-21T00:47:26+00:00

Allocate a NULL-terminated file path with special characters escaped,
safe for logging.

Signed-off-by: Kees Cook 
Signed-off-by: James Morris

string_helpers: add kstrdup_quotable_cmdline

2016-04-21T00:47:26+00:00

Provide an escaped (but readable: no inter-argument NULLs) commandline
safe for logging.

Signed-off-by: Kees Cook 
Signed-off-by: James Morris

string_helpers: add kstrdup_quotable

2016-04-21T00:47:25+00:00

Handle allocating and escaping a string safe for logging.

Signed-off-by: Kees Cook 
Signed-off-by: James Morris

string_helpers: fix precision loss for some inputs

2016-01-21T01:09:18+00:00

It was noticed that we lose precision in the final calculation for some
inputs.  The most egregious example is size=3000 blk_size=1900 in units
of 10 should yield 5.70 MB but in fact yields 3.00 MB (oops).

This is because the current algorithm doesn't correctly account for
all the remainders in the logarithms.  Fix this by doing a correct
calculation in the remainders based on napier's algorithm.

Additionally, now we have the correct result, we have to account for
arithmetic rounding because we're printing 3 digits of precision.  This
means that if the fourth digit is five or greater, we have to round up,
so add a section to ensure correct rounding.  Finally account for all
possible inputs correctly, including zero for block size.

Fixes: b9f28d863594c429e1df35a0474d2663ca28b307
Signed-off-by: James Bottomley 
Reported-by: Vitaly Kuznetsov 
Cc: 	[delay until after 4.4 release]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

lib/string_helpers.c: fix infinite loop in string_get_size()

2015-09-18T04:16:07+00:00

Some string_get_size() calls (e.g.:
 string_get_size(1, 512, STRING_UNITS_10, ..., ...)
 string_get_size(15, 64, STRING_UNITS_10, ..., ...)
) result in an infinite loop. The problem is that if size is equal to
divisor[units]/blk_size and is smaller than divisor[units] we'll end
up with size == 0 when we start doing sf_cap calculations:

For string_get_size(1, 512, STRING_UNITS_10, ..., ...) case:
   ...
   remainder = do_div(size, divisor[units]); -> size is 0, remainder is 1
   remainder *= blk_size; -> remainder is 512
   ...
   size *= blk_size; -> size is still 0
   size += remainder / divisor[units]; -> size is still 0

The caller causing the issue is sd_read_capacity(), the problem was
noticed on Hyper-V, such weird size was reported by host when scanning
collides with device removal.  This is probably a separate issue worth
fixing, this patch is intended to prevent the library routine from
infinite looping.

Signed-off-by: Vitaly Kuznetsov 
Acked-by: James Bottomley 
Cc: Andy Shevchenko 
Cc: Rasmus Villemoes 
Cc: "K. Y. Srinivasan" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds