[PATCH] malloc: fix definition for MAX_TCACHE_SMALL_SIZE

[Arjun Shankar]

Hi Cupertino,

> This patch fixes an incorrect definition of MAX_TCACHE_SMALL_SIZE which
> was missed by me and passed through review process.
> Wilco: Thank you for the finding.

So, looking at commit cbfd7988107b27b9ff1d0b57fa2c8f13a932e508 which
added support for large chunk caching:

-# define TCACHE_MAX_BINS               64
-# define MAX_TCACHE_SIZE       tidx2usize (TCACHE_MAX_BINS-1)
+# define TCACHE_SMALL_BINS             64
+# define TCACHE_LARGE_BINS             12 /* Up to 4M chunks */
+# define TCACHE_MAX_BINS       (TCACHE_SMALL_BINS + TCACHE_LARGE_BINS)
+# define MAX_TCACHE_SMALL_SIZE tidx2usize (TCACHE_MAX_BINS-1)

... looks like the intention was to have TCACHE_SMALL_BINS and
MAX_TCACHE_SMALL_SIZE represent the "default" (non large) chunks and
this definition was a bit of a "typo".

Wilco noticed this here:
https://inbox.sourceware.org/libc-alpha/DB3PR08MB89867BB318B699FAF1D133458361A@DB3PR08MB8986.eurprd08.prod.outlook.com/

This patch looks good to me.

Reviewed-by: Arjun Shankar <arjun@redhat.com>

I'm going to drop the "cover letter" that inadvertently got added as a
commit message when pushing this.

> ---
>  malloc/malloc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/malloc/malloc.c b/malloc/malloc.c
> index 3f91ff44b3..d522617f2b 100644
> --- a/malloc/malloc.c
> +++ b/malloc/malloc.c
> @@ -294,7 +294,7 @@
>  # define TCACHE_SMALL_BINS             64
>  # define TCACHE_LARGE_BINS             12 /* Up to 4M chunks */
>  # define TCACHE_MAX_BINS       (TCACHE_SMALL_BINS + TCACHE_LARGE_BINS)
> -# define MAX_TCACHE_SMALL_SIZE tidx2usize (TCACHE_MAX_BINS-1)
> +# define MAX_TCACHE_SMALL_SIZE tidx2usize (TCACHE_SMALL_BINS-1)

OK.

>
>  /* Only used to pre-fill the tunables.  */
>  # define tidx2usize(idx)       (((size_t) idx) * MALLOC_ALIGNMENT + MINSIZE - SIZE_SZ)
> --
> 2.30.2
>

--
Arjun Shankar
he/him/his