<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/lib, branch v6.13-rc2</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>Merge tag 'mm-hotfixes-stable-2024-12-07-22-39' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2024-12-08T19:26:13+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-12-08T19:26:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=553c89ec31746ff96fc5562943fe5b1c9b1e9276'/>
<id>553c89ec31746ff96fc5562943fe5b1c9b1e9276</id>
<content type='text'>
Pull misc fixes from Andrew Morton:
 "24 hotfixes.  17 are cc:stable.  15 are MM and 9 are non-MM.

  The usual bunch of singletons - please see the relevant changelogs for
  details"

* tag 'mm-hotfixes-stable-2024-12-07-22-39' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (24 commits)
  iio: magnetometer: yas530: use signed integer type for clamp limits
  sched/numa: fix memory leak due to the overwritten vma-&gt;numab_state
  mm/damon: fix order of arguments in damos_before_apply tracepoint
  lib: stackinit: hide never-taken branch from compiler
  mm/filemap: don't call folio_test_locked() without a reference in next_uptodate_folio()
  scatterlist: fix incorrect func name in kernel-doc
  mm: correct typo in MMAP_STATE() macro
  mm: respect mmap hint address when aligning for THP
  mm: memcg: declare do_memsw_account inline
  mm/codetag: swap tags when migrate pages
  ocfs2: update seq_file index in ocfs2_dlm_seq_next
  stackdepot: fix stack_depot_save_flags() in NMI context
  mm: open-code page_folio() in dump_page()
  mm: open-code PageTail in folio_flags() and const_folio_flags()
  mm: fix vrealloc()'s KASAN poisoning logic
  Revert "readahead: properly shorten readahead when falling back to do_page_cache_ra()"
  selftests/damon: add _damon_sysfs.py to TEST_FILES
  selftest: hugetlb_dio: fix test naming
  ocfs2: free inode when ocfs2_get_init_inode() fails
  nilfs2: fix potential out-of-bounds memory access in nilfs_find_entry()
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull misc fixes from Andrew Morton:
 "24 hotfixes.  17 are cc:stable.  15 are MM and 9 are non-MM.

  The usual bunch of singletons - please see the relevant changelogs for
  details"

* tag 'mm-hotfixes-stable-2024-12-07-22-39' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (24 commits)
  iio: magnetometer: yas530: use signed integer type for clamp limits
  sched/numa: fix memory leak due to the overwritten vma-&gt;numab_state
  mm/damon: fix order of arguments in damos_before_apply tracepoint
  lib: stackinit: hide never-taken branch from compiler
  mm/filemap: don't call folio_test_locked() without a reference in next_uptodate_folio()
  scatterlist: fix incorrect func name in kernel-doc
  mm: correct typo in MMAP_STATE() macro
  mm: respect mmap hint address when aligning for THP
  mm: memcg: declare do_memsw_account inline
  mm/codetag: swap tags when migrate pages
  ocfs2: update seq_file index in ocfs2_dlm_seq_next
  stackdepot: fix stack_depot_save_flags() in NMI context
  mm: open-code page_folio() in dump_page()
  mm: open-code PageTail in folio_flags() and const_folio_flags()
  mm: fix vrealloc()'s KASAN poisoning logic
  Revert "readahead: properly shorten readahead when falling back to do_page_cache_ra()"
  selftests/damon: add _damon_sysfs.py to TEST_FILES
  selftest: hugetlb_dio: fix test naming
  ocfs2: free inode when ocfs2_get_init_inode() fails
  nilfs2: fix potential out-of-bounds memory access in nilfs_find_entry()
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>lib: stackinit: hide never-taken branch from compiler</title>
<updated>2024-12-06T03:54:47+00:00</updated>
<author>
<name>Kees Cook</name>
<email>kees@kernel.org</email>
</author>
<published>2024-11-17T11:38:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5c3793604f91123bf49bc792ce697a0bef4c173c'/>
<id>5c3793604f91123bf49bc792ce697a0bef4c173c</id>
<content type='text'>
The never-taken branch leads to an invalid bounds condition, which is by
design. To avoid the unwanted warning from the compiler, hide the
variable from the optimizer.

../lib/stackinit_kunit.c: In function 'do_nothing_u16_zero':
../lib/stackinit_kunit.c:51:49: error: array subscript 1 is outside array bounds of 'u16[0]' {aka 'short unsigned int[]'} [-Werror=array-bounds=]
   51 | #define DO_NOTHING_RETURN_SCALAR(ptr)           *(ptr)
      |                                                 ^~~~~~
../lib/stackinit_kunit.c:219:24: note: in expansion of macro 'DO_NOTHING_RETURN_SCALAR'
  219 |                 return DO_NOTHING_RETURN_ ## which(ptr + 1);    \
      |                        ^~~~~~~~~~~~~~~~~~

Link: https://lkml.kernel.org/r/20241117113813.work.735-kees@kernel.org
Signed-off-by: Kees Cook &lt;kees@kernel.org&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The never-taken branch leads to an invalid bounds condition, which is by
design. To avoid the unwanted warning from the compiler, hide the
variable from the optimizer.

../lib/stackinit_kunit.c: In function 'do_nothing_u16_zero':
../lib/stackinit_kunit.c:51:49: error: array subscript 1 is outside array bounds of 'u16[0]' {aka 'short unsigned int[]'} [-Werror=array-bounds=]
   51 | #define DO_NOTHING_RETURN_SCALAR(ptr)           *(ptr)
      |                                                 ^~~~~~
../lib/stackinit_kunit.c:219:24: note: in expansion of macro 'DO_NOTHING_RETURN_SCALAR'
  219 |                 return DO_NOTHING_RETURN_ ## which(ptr + 1);    \
      |                        ^~~~~~~~~~~~~~~~~~

Link: https://lkml.kernel.org/r/20241117113813.work.735-kees@kernel.org
Signed-off-by: Kees Cook &lt;kees@kernel.org&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/codetag: swap tags when migrate pages</title>
<updated>2024-12-06T03:54:46+00:00</updated>
<author>
<name>David Wang</name>
<email>00107082@163.com</email>
</author>
<published>2024-11-29T02:52:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=51f43d5d82ed2ba3f9a3f9a2390c52f28e42af32'/>
<id>51f43d5d82ed2ba3f9a3f9a2390c52f28e42af32</id>
<content type='text'>
Current solution to adjust codetag references during page migration is
done in 3 steps:

1. sets the codetag reference of the old page as empty (not pointing
   to any codetag);

2. subtracts counters of the new page to compensate for its own
   allocation;

3. sets codetag reference of the new page to point to the codetag of
   the old page.

This does not work if CONFIG_MEM_ALLOC_PROFILING_DEBUG=n because
set_codetag_empty() becomes NOOP.  Instead, let's simply swap codetag
references so that the new page is referencing the old codetag and the old
page is referencing the new codetag.  This way accounting stays valid and
the logic makes more sense.

Link: https://lkml.kernel.org/r/20241129025213.34836-1-00107082@163.com
Fixes: e0a955bf7f61 ("mm/codetag: add pgalloc_tag_copy()")
Signed-off-by: David Wang &lt;00107082@163.com&gt;
Closes: https://lore.kernel.org/lkml/20241124074318.399027-1-00107082@163.com/
Acked-by: Suren Baghdasaryan &lt;surenb@google.com&gt;
Suggested-by: Suren Baghdasaryan &lt;surenb@google.com&gt;
Acked-by: Yu Zhao &lt;yuzhao@google.com&gt;
Cc: Kent Overstreet &lt;kent.overstreet@linux.dev&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Current solution to adjust codetag references during page migration is
done in 3 steps:

1. sets the codetag reference of the old page as empty (not pointing
   to any codetag);

2. subtracts counters of the new page to compensate for its own
   allocation;

3. sets codetag reference of the new page to point to the codetag of
   the old page.

This does not work if CONFIG_MEM_ALLOC_PROFILING_DEBUG=n because
set_codetag_empty() becomes NOOP.  Instead, let's simply swap codetag
references so that the new page is referencing the old codetag and the old
page is referencing the new codetag.  This way accounting stays valid and
the logic makes more sense.

Link: https://lkml.kernel.org/r/20241129025213.34836-1-00107082@163.com
Fixes: e0a955bf7f61 ("mm/codetag: add pgalloc_tag_copy()")
Signed-off-by: David Wang &lt;00107082@163.com&gt;
Closes: https://lore.kernel.org/lkml/20241124074318.399027-1-00107082@163.com/
Acked-by: Suren Baghdasaryan &lt;surenb@google.com&gt;
Suggested-by: Suren Baghdasaryan &lt;surenb@google.com&gt;
Acked-by: Yu Zhao &lt;yuzhao@google.com&gt;
Cc: Kent Overstreet &lt;kent.overstreet@linux.dev&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>stackdepot: fix stack_depot_save_flags() in NMI context</title>
<updated>2024-12-06T03:54:45+00:00</updated>
<author>
<name>Marco Elver</name>
<email>elver@google.com</email>
</author>
<published>2024-11-22T15:39:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=031e04bdc834cda3b054ef6b698503b2b97e8186'/>
<id>031e04bdc834cda3b054ef6b698503b2b97e8186</id>
<content type='text'>
Per documentation, stack_depot_save_flags() was meant to be usable from
NMI context if STACK_DEPOT_FLAG_CAN_ALLOC is unset.  However, it still
would try to take the pool_lock in an attempt to save a stack trace in the
current pool (if space is available).

This could result in deadlock if an NMI is handled while pool_lock is
already held.  To avoid deadlock, only try to take the lock in NMI context
and give up if unsuccessful.

The documentation is fixed to clearly convey this.

Link: https://lkml.kernel.org/r/Z0CcyfbPqmxJ9uJH@elver.google.com
Link: https://lkml.kernel.org/r/20241122154051.3914732-1-elver@google.com
Fixes: 4434a56ec209 ("stackdepot: make fast paths lock-less again")
Signed-off-by: Marco Elver &lt;elver@google.com&gt;
Reported-by: Sebastian Andrzej Siewior &lt;bigeasy@linutronix.de&gt;
Reviewed-by: Sebastian Andrzej Siewior &lt;bigeasy@linutronix.de&gt;
Cc: Alexander Potapenko &lt;glider@google.com&gt;
Cc: Andrey Konovalov &lt;andreyknvl@gmail.com&gt;
Cc: Dmitry Vyukov &lt;dvyukov@google.com&gt;
Cc: Oscar Salvador &lt;osalvador@suse.de&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Per documentation, stack_depot_save_flags() was meant to be usable from
NMI context if STACK_DEPOT_FLAG_CAN_ALLOC is unset.  However, it still
would try to take the pool_lock in an attempt to save a stack trace in the
current pool (if space is available).

This could result in deadlock if an NMI is handled while pool_lock is
already held.  To avoid deadlock, only try to take the lock in NMI context
and give up if unsuccessful.

The documentation is fixed to clearly convey this.

Link: https://lkml.kernel.org/r/Z0CcyfbPqmxJ9uJH@elver.google.com
Link: https://lkml.kernel.org/r/20241122154051.3914732-1-elver@google.com
Fixes: 4434a56ec209 ("stackdepot: make fast paths lock-less again")
Signed-off-by: Marco Elver &lt;elver@google.com&gt;
Reported-by: Sebastian Andrzej Siewior &lt;bigeasy@linutronix.de&gt;
Reviewed-by: Sebastian Andrzej Siewior &lt;bigeasy@linutronix.de&gt;
Cc: Alexander Potapenko &lt;glider@google.com&gt;
Cc: Andrey Konovalov &lt;andreyknvl@gmail.com&gt;
Cc: Dmitry Vyukov &lt;dvyukov@google.com&gt;
Cc: Oscar Salvador &lt;osalvador@suse.de&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>module: Convert symbol namespace to string literal</title>
<updated>2024-12-02T19:34:44+00:00</updated>
<author>
<name>Peter Zijlstra</name>
<email>peterz@infradead.org</email>
</author>
<published>2024-12-02T14:59:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=cdd30ebb1b9f36159d66f088b61aee264e649d7a'/>
<id>cdd30ebb1b9f36159d66f088b61aee264e649d7a</id>
<content type='text'>
Clean up the existing export namespace code along the same lines of
commit 33def8498fdd ("treewide: Convert macro and uses of __section(foo)
to __section("foo")") and for the same reason, it is not desired for the
namespace argument to be a macro expansion itself.

Scripted using

  git grep -l -e MODULE_IMPORT_NS -e EXPORT_SYMBOL_NS | while read file;
  do
    awk -i inplace '
      /^#define EXPORT_SYMBOL_NS/ {
        gsub(/__stringify\(ns\)/, "ns");
        print;
        next;
      }
      /^#define MODULE_IMPORT_NS/ {
        gsub(/__stringify\(ns\)/, "ns");
        print;
        next;
      }
      /MODULE_IMPORT_NS/ {
        $0 = gensub(/MODULE_IMPORT_NS\(([^)]*)\)/, "MODULE_IMPORT_NS(\"\\1\")", "g");
      }
      /EXPORT_SYMBOL_NS/ {
        if ($0 ~ /(EXPORT_SYMBOL_NS[^(]*)\(([^,]+),/) {
  	if ($0 !~ /(EXPORT_SYMBOL_NS[^(]*)\(([^,]+), ([^)]+)\)/ &amp;&amp;
  	    $0 !~ /(EXPORT_SYMBOL_NS[^(]*)\(\)/ &amp;&amp;
  	    $0 !~ /^my/) {
  	  getline line;
  	  gsub(/[[:space:]]*\\$/, "");
  	  gsub(/[[:space:]]/, "", line);
  	  $0 = $0 " " line;
  	}

  	$0 = gensub(/(EXPORT_SYMBOL_NS[^(]*)\(([^,]+), ([^)]+)\)/,
  		    "\\1(\\2, \"\\3\")", "g");
        }
      }
      { print }' $file;
  done

Requested-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Link: https://mail.google.com/mail/u/2/#inbox/FMfcgzQXKWgMmjdFwwdsfgxzKpVHWPlc
Acked-by: Greg KH &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Clean up the existing export namespace code along the same lines of
commit 33def8498fdd ("treewide: Convert macro and uses of __section(foo)
to __section("foo")") and for the same reason, it is not desired for the
namespace argument to be a macro expansion itself.

Scripted using

  git grep -l -e MODULE_IMPORT_NS -e EXPORT_SYMBOL_NS | while read file;
  do
    awk -i inplace '
      /^#define EXPORT_SYMBOL_NS/ {
        gsub(/__stringify\(ns\)/, "ns");
        print;
        next;
      }
      /^#define MODULE_IMPORT_NS/ {
        gsub(/__stringify\(ns\)/, "ns");
        print;
        next;
      }
      /MODULE_IMPORT_NS/ {
        $0 = gensub(/MODULE_IMPORT_NS\(([^)]*)\)/, "MODULE_IMPORT_NS(\"\\1\")", "g");
      }
      /EXPORT_SYMBOL_NS/ {
        if ($0 ~ /(EXPORT_SYMBOL_NS[^(]*)\(([^,]+),/) {
  	if ($0 !~ /(EXPORT_SYMBOL_NS[^(]*)\(([^,]+), ([^)]+)\)/ &amp;&amp;
  	    $0 !~ /(EXPORT_SYMBOL_NS[^(]*)\(\)/ &amp;&amp;
  	    $0 !~ /^my/) {
  	  getline line;
  	  gsub(/[[:space:]]*\\$/, "");
  	  gsub(/[[:space:]]/, "", line);
  	  $0 = $0 " " line;
  	}

  	$0 = gensub(/(EXPORT_SYMBOL_NS[^(]*)\(([^,]+), ([^)]+)\)/,
  		    "\\1(\\2, \"\\3\")", "g");
        }
      }
      { print }' $file;
  done

Requested-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Link: https://mail.google.com/mail/u/2/#inbox/FMfcgzQXKWgMmjdFwwdsfgxzKpVHWPlc
Acked-by: Greg KH &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'trace-printf-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace</title>
<updated>2024-12-01T21:10:51+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-12-01T21:10:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=88862eeb476375687a1de5f45528a437ea598338'/>
<id>88862eeb476375687a1de5f45528a437ea598338</id>
<content type='text'>
Pull bprintf() removal from Steven Rostedt:

 - Remove unused bprintf() function, that was added with the rest of the
   "bin-printf" functions.

   These are functions that are used by trace_printk() that allows to
   quickly save the format and arguments into the ring buffer without
   the expensive processing of converting numbers to ASCII. Then on
   output, at a much later time, the ring buffer is read and the string
   processing occurs then. The bprintf() was added for consistency but
   was never used. It can be safely removed.

* tag 'trace-printf-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  printf: Remove unused 'bprintf'
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull bprintf() removal from Steven Rostedt:

 - Remove unused bprintf() function, that was added with the rest of the
   "bin-printf" functions.

   These are functions that are used by trace_printk() that allows to
   quickly save the format and arguments into the ring buffer without
   the expensive processing of converting numbers to ASCII. Then on
   output, at a much later time, the ring buffer is read and the string
   processing occurs then. The bprintf() was added for consistency but
   was never used. It can be safely removed.

* tag 'trace-printf-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  printf: Remove unused 'bprintf'
</pre>
</div>
</content>
</entry>
<entry>
<title>strscpy: write destination buffer only once</title>
<updated>2024-12-01T20:17:16+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-12-01T17:23:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=9022ed0e7e65734d83a0648648589b9fbea8e8c9'/>
<id>9022ed0e7e65734d83a0648648589b9fbea8e8c9</id>
<content type='text'>
The point behind strscpy() was to once and for all avoid all the
problems with 'strncpy()' and later broken "fixed" versions like
strlcpy() that just made things worse.

So strscpy not only guarantees NUL-termination (unlike strncpy), it also
doesn't do unnecessary padding at the destination.  But at the same time
also avoids byte-at-a-time reads and writes by _allowing_ some extra NUL
writes - within the size, of course - so that the whole copy can be done
with word operations.

It is also stable in the face of a mutable source string: it explicitly
does not read the source buffer multiple times (so an implementation
using "strnlen()+memcpy()" would be wrong), and does not read the source
buffer past the size (like the mis-design that is strlcpy does).

Finally, the return value is designed to be simple and unambiguous: if
the string cannot be copied fully, it returns an actual negative error,
making error handling clearer and simpler (and the caller already knows
the size of the buffer).  Otherwise it returns the string length of the
result.

However, there was one final stability issue that can be important to
callers: the stability of the destination buffer.

In particular, the same way we shouldn't read the source buffer more
than once, we should avoid doing multiple writes to the destination
buffer: first writing a potentially non-terminated string, and then
terminating it with NUL at the end does not result in a stable result
buffer.

Yes, it gives the right result in the end, but if the rule for the
destination buffer was that it is _always_ NUL-terminated even when
accessed concurrently with updates, the final byte of the buffer needs
to always _stay_ as a NUL byte.

[ Note that "final byte is NUL" here is literally about the final byte
  in the destination array, not the terminating NUL at the end of the
  string itself. There is no attempt to try to make concurrent reads and
  writes give any kind of consistent string length or contents, but we
  do want to guarantee that there is always at least that final
  terminating NUL character at the end of the destination array if it
  existed before ]

This is relevant in the kernel for the tsk-&gt;comm[] array, for example.
Even without locking (for either readers or writers), we want to know
that while the buffer contents may be garbled, it is always a valid C
string and always has a NUL character at 'comm[TASK_COMM_LEN-1]' (and
never has any "out of thin air" data).

So avoid any "copy possibly non-terminated string, and terminate later"
behavior, and write the destination buffer only once.

Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The point behind strscpy() was to once and for all avoid all the
problems with 'strncpy()' and later broken "fixed" versions like
strlcpy() that just made things worse.

So strscpy not only guarantees NUL-termination (unlike strncpy), it also
doesn't do unnecessary padding at the destination.  But at the same time
also avoids byte-at-a-time reads and writes by _allowing_ some extra NUL
writes - within the size, of course - so that the whole copy can be done
with word operations.

It is also stable in the face of a mutable source string: it explicitly
does not read the source buffer multiple times (so an implementation
using "strnlen()+memcpy()" would be wrong), and does not read the source
buffer past the size (like the mis-design that is strlcpy does).

Finally, the return value is designed to be simple and unambiguous: if
the string cannot be copied fully, it returns an actual negative error,
making error handling clearer and simpler (and the caller already knows
the size of the buffer).  Otherwise it returns the string length of the
result.

However, there was one final stability issue that can be important to
callers: the stability of the destination buffer.

In particular, the same way we shouldn't read the source buffer more
than once, we should avoid doing multiple writes to the destination
buffer: first writing a potentially non-terminated string, and then
terminating it with NUL at the end does not result in a stable result
buffer.

Yes, it gives the right result in the end, but if the rule for the
destination buffer was that it is _always_ NUL-terminated even when
accessed concurrently with updates, the final byte of the buffer needs
to always _stay_ as a NUL byte.

[ Note that "final byte is NUL" here is literally about the final byte
  in the destination array, not the terminating NUL at the end of the
  string itself. There is no attempt to try to make concurrent reads and
  writes give any kind of consistent string length or contents, but we
  do want to guarantee that there is always at least that final
  terminating NUL character at the end of the destination array if it
  existed before ]

This is relevant in the kernel for the tsk-&gt;comm[] array, for example.
Even without locking (for either readers or writers), we want to know
that while the buffer contents may be garbled, it is always a valid C
string and always has a NUL character at 'comm[TASK_COMM_LEN-1]' (and
never has any "out of thin air" data).

So avoid any "copy possibly non-terminated string, and terminate later"
behavior, and write the destination buffer only once.

Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>printf: Remove unused 'bprintf'</title>
<updated>2024-12-01T03:41:35+00:00</updated>
<author>
<name>Dr. David Alan Gilbert</name>
<email>linux@treblig.org</email>
</author>
<published>2024-10-02T17:31:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=f69e63756f7822fcdad8a34f9967e8b243e883ee'/>
<id>f69e63756f7822fcdad8a34f9967e8b243e883ee</id>
<content type='text'>
bprintf() is unused. Remove it. It was added in the commit 4370aa4aa753
("vsprintf: add binary printf") but as far as I can see was never used,
unlike the other two functions in that patch.

Link: https://lore.kernel.org/20241002173147.210107-1-linux@treblig.org
Reviewed-by: Andy Shevchenko &lt;andy@kernel.org&gt;
Acked-by: Petr Mladek &lt;pmladek@suse.com&gt;
Signed-off-by: Dr. David Alan Gilbert &lt;linux@treblig.org&gt;
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
bprintf() is unused. Remove it. It was added in the commit 4370aa4aa753
("vsprintf: add binary printf") but as far as I can see was never used,
unlike the other two functions in that patch.

Link: https://lore.kernel.org/20241002173147.210107-1-linux@treblig.org
Reviewed-by: Andy Shevchenko &lt;andy@kernel.org&gt;
Acked-by: Petr Mladek &lt;pmladek@suse.com&gt;
Signed-off-by: Dr. David Alan Gilbert &lt;linux@treblig.org&gt;
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'driver-core-6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core</title>
<updated>2024-11-29T19:43:29+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-11-29T19:43:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=55cb93fd243bad2c6e15f9151a32f575d2f5371f'/>
<id>55cb93fd243bad2c6e15f9151a32f575d2f5371f</id>
<content type='text'>
Pull driver core updates from Greg KH:
 "Here is a small set of driver core changes for 6.13-rc1.

  Nothing major for this merge cycle, except for the two simple merge
  conflicts are here just to make life interesting.

  Included in here are:

   - sysfs core changes and preparations for more sysfs api cleanups
     that can come through all driver trees after -rc1 is out

   - fw_devlink fixes based on many reports and debugging sessions

   - list_for_each_reverse() removal, no one was using it!

   - last-minute seq_printf() format string bug found and fixed in many
     drivers all at once.

   - minor bugfixes and changes full details in the shortlog"

* tag 'driver-core-6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (35 commits)
  Fix a potential abuse of seq_printf() format string in drivers
  cpu: Remove spurious NULL in attribute_group definition
  s390/con3215: Remove spurious NULL in attribute_group definition
  perf: arm-ni: Remove spurious NULL in attribute_group definition
  driver core: Constify bin_attribute definitions
  sysfs: attribute_group: allow registration of const bin_attribute
  firmware_loader: Fix possible resource leak in fw_log_firmware_info()
  drivers: core: fw_devlink: Fix excess parameter description in docstring
  driver core: class: Correct WARN() message in APIs class_(for_each|find)_device()
  cacheinfo: Use of_property_present() for non-boolean properties
  cdx: Fix cdx_mmap_resource() after constifying attr in -&gt;mmap()
  drivers: core: fw_devlink: Make the error message a bit more useful
  phy: tegra: xusb: Set fwnode for xusb port devices
  drm: display: Set fwnode for aux bus devices
  driver core: fw_devlink: Stop trying to optimize cycle detection logic
  driver core: Constify attribute arguments of binary attributes
  sysfs: bin_attribute: add const read/write callback variants
  sysfs: implement all BIN_ATTR_* macros in terms of __BIN_ATTR()
  sysfs: treewide: constify attribute callback of bin_attribute::llseek()
  sysfs: treewide: constify attribute callback of bin_attribute::mmap()
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull driver core updates from Greg KH:
 "Here is a small set of driver core changes for 6.13-rc1.

  Nothing major for this merge cycle, except for the two simple merge
  conflicts are here just to make life interesting.

  Included in here are:

   - sysfs core changes and preparations for more sysfs api cleanups
     that can come through all driver trees after -rc1 is out

   - fw_devlink fixes based on many reports and debugging sessions

   - list_for_each_reverse() removal, no one was using it!

   - last-minute seq_printf() format string bug found and fixed in many
     drivers all at once.

   - minor bugfixes and changes full details in the shortlog"

* tag 'driver-core-6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (35 commits)
  Fix a potential abuse of seq_printf() format string in drivers
  cpu: Remove spurious NULL in attribute_group definition
  s390/con3215: Remove spurious NULL in attribute_group definition
  perf: arm-ni: Remove spurious NULL in attribute_group definition
  driver core: Constify bin_attribute definitions
  sysfs: attribute_group: allow registration of const bin_attribute
  firmware_loader: Fix possible resource leak in fw_log_firmware_info()
  drivers: core: fw_devlink: Fix excess parameter description in docstring
  driver core: class: Correct WARN() message in APIs class_(for_each|find)_device()
  cacheinfo: Use of_property_present() for non-boolean properties
  cdx: Fix cdx_mmap_resource() after constifying attr in -&gt;mmap()
  drivers: core: fw_devlink: Make the error message a bit more useful
  phy: tegra: xusb: Set fwnode for xusb port devices
  drm: display: Set fwnode for aux bus devices
  driver core: fw_devlink: Stop trying to optimize cycle detection logic
  driver core: Constify attribute arguments of binary attributes
  sysfs: bin_attribute: add const read/write callback variants
  sysfs: implement all BIN_ATTR_* macros in terms of __BIN_ATTR()
  sysfs: treewide: constify attribute callback of bin_attribute::llseek()
  sysfs: treewide: constify attribute callback of bin_attribute::mmap()
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>selftests: kallsyms: fix and clarify current test boundaries</title>
<updated>2024-11-28T19:17:30+00:00</updated>
<author>
<name>Luis Chamberlain</name>
<email>mcgrof@kernel.org</email>
</author>
<published>2024-11-28T03:06:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=3e1d95b63c97506d0d98c75fc72a60662981a3c6'/>
<id>3e1d95b63c97506d0d98c75fc72a60662981a3c6</id>
<content type='text'>
Provide and clarify the existing ranges and what you should expect.
Fix the gen_test_kallsyms.sh script to accept different ranges.

Fixes: 84b4a51fce4ccc66 ("selftests: add new kallsyms selftests")
Signed-off-by: Luis Chamberlain &lt;mcgrof@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Provide and clarify the existing ranges and what you should expect.
Fix the gen_test_kallsyms.sh script to accept different ranges.

Fixes: 84b4a51fce4ccc66 ("selftests: add new kallsyms selftests")
Signed-off-by: Luis Chamberlain &lt;mcgrof@kernel.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
