2022-09-27 13:51:40

by Miguel Ojeda

Subject: [PATCH v10 03/27] kallsyms: add static relationship between `KSYM_NAME_LEN{,_BUFFER}`

This adds a static assert to ensure `KSYM_NAME_LEN_BUFFER`
gets updated when `KSYM_NAME_LEN` changes.

The relationship used is one that keeps the new size (512+1)
close to the original buffer size (500).

Co-developed-by: Boqun Feng <[email protected]>
Signed-off-by: Boqun Feng <[email protected]>
Signed-off-by: Miguel Ojeda <[email protected]>
---
scripts/kallsyms.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 25e2fe5fbcd4..411ff5058b51 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -32,8 +32,18 @@

#define KSYM_NAME_LEN 128

-/* A substantially bigger size than the current maximum. */
-#define KSYM_NAME_LEN_BUFFER 499
+/*
+ * A substantially bigger size than the current maximum.
+ *
+ * It cannot be defined as an expression because it gets stringified
+ * for the fscanf() format string. Therefore, a _Static_assert() is
+ * used instead to maintain the relationship with KSYM_NAME_LEN.
+ */
+#define KSYM_NAME_LEN_BUFFER 512
+_Static_assert(
+ KSYM_NAME_LEN_BUFFER == KSYM_NAME_LEN * 4,
+ "Please keep KSYM_NAME_LEN_BUFFER in sync with KSYM_NAME_LEN"
+);

struct sym_entry {
unsigned long long addr;
--
2.37.3

2022-09-27 15:23:08

by Greg Kroah-Hartman

Subject: Re: [PATCH v10 03/27] kallsyms: add static relationship between `KSYM_NAME_LEN{,_BUFFER}`

On Tue, Sep 27, 2022 at 03:14:34PM +0200, Miguel Ojeda wrote:
> This adds a static assert to ensure `KSYM_NAME_LEN_BUFFER`
> gets updated when `KSYM_NAME_LEN` changes.
>
> The relationship used is one that keeps the new size (512+1)
> close to the original buffer size (500).
>
> Co-developed-by: Boqun Feng <[email protected]>
> Signed-off-by: Boqun Feng <[email protected]>
> Signed-off-by: Miguel Ojeda <[email protected]>
> ---
> scripts/kallsyms.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
> index 25e2fe5fbcd4..411ff5058b51 100644
> --- a/scripts/kallsyms.c
> +++ b/scripts/kallsyms.c
> @@ -32,8 +32,18 @@
>
> #define KSYM_NAME_LEN 128
>
> -/* A substantially bigger size than the current maximum. */
> -#define KSYM_NAME_LEN_BUFFER 499
> +/*
> + * A substantially bigger size than the current maximum.
> + *
> + * It cannot be defined as an expression because it gets stringified
> + * for the fscanf() format string. Therefore, a _Static_assert() is
> + * used instead to maintain the relationship with KSYM_NAME_LEN.
> + */
> +#define KSYM_NAME_LEN_BUFFER 512
> +_Static_assert(
> + KSYM_NAME_LEN_BUFFER == KSYM_NAME_LEN * 4,
> + "Please keep KSYM_NAME_LEN_BUFFER in sync with KSYM_NAME_LEN"
> +);

Messy, but I can't think of any other way right now either :(

Reviewed-by: Greg Kroah-Hartman <[email protected]>