The patch titled
Subject: fs/proc: fix build with GCC 15 due to -Werror=unterminated-string-initialization
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
fs-proc-fix-build-with-gcc-15-due-to-werror=unterminated-string-initialization.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fs-proc-fix-build-with-gcc-15-due-to-werror=unterminated-string-initialization.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Brahmajit Das <brahmajit.xyz@xxxxxxxxx>
Subject: fs/proc: fix build with GCC 15 due to -Werror=unterminated-string-initialization
Date: Sat, 5 Oct 2024 12:07:00 +0530
show show_smap_vma_flags() has been a using misspelled initializer in
mnemonics[] - it needed to initialize 2 element array of char and it used
NUL-padded 2 character string literals (i.e. 3-element initializer).
This has been spotted by gcc-15[*]; prior to that gcc quietly dropped the
3rd eleemnt of initializers. To fix this we are increasing the size of
mnemonics[] (from mnemonics[BITS_PER_LONG][2] to
mnemonics[BITS_PER_LONG][3]) to accomodate the NUL-padded string literals.
This also helps us in simplyfying the logic for printing of the flags as
instead of printing each character from the mnemonics[], we can just print
the mnemonics[] using seq_printf.
[*]: fs/proc/task_mmu.c:917:49: error: initializer-string for array of `char' is too long [-Werror=unterminate d-string-initialization]
917 | [0 ... (BITS_PER_LONG-1)] = "??",
| ^~~~
fs/proc/task_mmu.c:917:49: error: initializer-string for array of `char' is too long [-Werror=unterminate d-string-initialization]
fs/proc/task_mmu.c:917:49: error: initializer-string for array of `char' is too long [-Werror=unterminate d-string-initialization]
fs/proc/task_mmu.c:917:49: error: initializer-string for array of `char' is too long [-Werror=unterminate d-string-initialization]
fs/proc/task_mmu.c:917:49: error: initializer-string for array of `char' is too long [-Werror=unterminate d-string-initialization]
fs/proc/task_mmu.c:917:49: error: initializer-string for array of `char' is too long [-Werror=unterminate d-string-initialization]
...
Stephen pointed out:
: The C standard explicitly allows for a string initializer to be too long
: due to the NUL byte at the end ... so this warning may be overzealous.
but let's make the warning go away anwyay.
Link: https://lkml.kernel.org/r/20241005063700.2241027-1-brahmajit.xyz@xxxxxxxxx
Link: https://lkml.kernel.org/r/20241003093040.47c08382@xxxxxxxxxxxxxxxx
Signed-off-by: Brahmajit Das <brahmajit.xyz@xxxxxxxxx>
Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
--- a/fs/proc/task_mmu.c~fs-proc-fix-build-with-gcc-15-due-to-werror=unterminated-string-initialization
+++ a/fs/proc/task_mmu.c
@@ -909,8 +909,15 @@ static void show_smap_vma_flags(struct s
{
/*
* Don't forget to update Documentation/ on changes.
+ *
+ * The length of the second argument of mnemonics[]
+ * needs to be 3 instead of previously set 2
+ * (i.e. from [BITS_PER_LONG][2] to [BITS_PER_LONG][3])
+ * to avoid spurious
+ * -Werror=unterminated-string-initialization warning
+ * with GCC 15
*/
- static const char mnemonics[BITS_PER_LONG][2] = {
+ static const char mnemonics[BITS_PER_LONG][3] = {
/*
* In case if we meet a flag we don't know about.
*/
@@ -987,11 +994,8 @@ static void show_smap_vma_flags(struct s
for (i = 0; i < BITS_PER_LONG; i++) {
if (!mnemonics[i][0])
continue;
- if (vma->vm_flags & (1UL << i)) {
- seq_putc(m, mnemonics[i][0]);
- seq_putc(m, mnemonics[i][1]);
- seq_putc(m, ' ');
- }
+ if (vma->vm_flags & (1UL << i))
+ seq_printf(m, "%s ", mnemonics[i]);
}
seq_putc(m, '\n');
}
_
Patches currently in -mm which might be from brahmajit.xyz@xxxxxxxxx are
fs-proc-fix-build-with-gcc-15-due-to-werror=unterminated-string-initialization.patch
