From: Andrew Morton <akpm@linux-foundation•org>
To: Brahmajit Das <brahmajit.xyz@gmail•com>
Cc: david@redhat•com, gorcunov@openvz•org, linux-next@vger•kernel.org
Subject: Re: [PATCH v2 1/1] fs: proc: Fix build with GCC 15 due to -Werror=unterminated-string-initialization
Date: Wed, 2 Oct 2024 14:48:06 -0700 [thread overview]
Message-ID: <20241002144806.255d62115286e173bbf42655@linux-foundation.org> (raw)
In-Reply-To: <20241002080914.841071-1-brahmajit.xyz@gmail.com>
On Wed, 2 Oct 2024 13:39:14 +0530 Brahmajit Das <brahmajit.xyz@gmail•com> wrote:
> GCC 15 enables -Werror=unterminated-string-initialization by default.
> This results in the following build error/s
> 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]
> ...
>
> To fix this, the length of the second argument of arary mnemonics needs
"array"
> to be 3 instead of previously set 2 (i.e. from [BITS_PER_LONG][2] to
> [BITS_PER_LONG][3])
>
Yes, I'm not surprised that little party trick we used in there fools
gcc. And really it deserves to die.
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -909,8 +909,15 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
> {
> /*
> * Don't forget to update Documentation/ on changes.
> + *
> + * The length of the second argument of arary mnemonics
"array". But really, just using "mnemonics[]" conveys all we need.
> + * 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.
> */
If we want to preserve the party trick then perhaps we can use
- [0 ... (BITS_PER_LONG-1)] = { "??" },
+ [0 ... (BITS_PER_LONG-1)] = { '?', '?' },
and this will shut gcc up?
If we do remove the party trick (as you have done) then this:
if (vma->vm_flags & (1UL << i)) {
seq_putc(m, mnemonics[i][0]);
seq_putc(m, mnemonics[i][1]);
seq_putc(m, ' ');
}
can be simplified (and probably sped up) with
if (vma->vm_flags & (1UL << i))
seq_printf(m, "%s ", mnemonics[i]);
yes?
next prev parent reply other threads:[~2024-10-02 21:48 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-02 8:05 [PATCH 1/1] fs: proc: Fix build with GCC 15 due to -Werror=unterminated-string-initialization Brahmajit Das
2024-10-02 8:09 ` [PATCH v2 " Brahmajit Das
2024-10-02 21:48 ` Andrew Morton [this message]
2024-10-02 23:30 ` Stephen Rothwell
2024-10-02 23:39 ` Stephen Rothwell
2024-10-04 20:16 ` Brahmajit
2024-10-04 21:12 ` Brahmajit
2024-10-04 21:58 ` Andrew Morton
2024-10-05 6:37 ` [PATCH v3 1/1] fs/proc: " Brahmajit Das
2024-10-08 2:08 ` Andrew Morton
2024-10-28 8:02 ` Cyrill Gorcunov
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