[Crash-utility] Re: [PATCH v3 ] Adding the zram decompression algorithm "lzo-rle" to support kernel versions >= 5.1
On 2024/03/26 15:38, Tang Yulong wrote:
Hi, Kazu
Thank you for your review.
> On 2024/03/12 17:25, Yulong TANG 汤玉龙 wrote:
>
> Thanks for the update.
>
>
> why are this ifdef and lzo_init() etc. needed? I think we do not use
> the lzo library for lzo-rle. maybe I'm missing something..
Yes, you are right. we do not use the lzo library for lzo-rle.
the "lzorle_decompress_safe" function should be directly used here.
>
>
> There is no need to check this every call, how about making this static?
> for example:
>
> static int efficient_unaligned_access = -1;
> if (efficient_unaligned_access == -1) {
> #if defined(ARM) || defined(ARM64) || defined(X86) || defined(X86_64) ||
> defined(PPC) || defined(PPC64) || defined(S390)|| defined(S390X)
> efficient_unaligned_access = TRUE;
> #else
> efficient_unaligned_access = FALSE;
> #endif
> if ((kt->ikconfig_flags & IKCONFIG_AVAIL) &&
> (get_kernel_config("CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS", NULL)
> == IKCONFIG_Y)
> efficient_unaligned_access = TRUE;
> }
This is a good approach to avoid checking every call,
I've made those modifications we talked about, tested, and it's looking good.
Anything else we should optimize?
Thank you for testing. a nit, we use 'ulong' for unsigned long usually,
otherwise looks fine to me.
Thanks,
Kazu
>
> Thanks,
> Yulong
>
> --- a/diskdump.c
> +++ b/diskdump.c
> @@ -3070,20 +3070,7 @@ try_zram_decompress(ulonglong pte_val, unsigned char *buf,
ulong len, ulonglong
> return 0;
> #endif
> } else if (STREQ(name, "lzo-rle")) {
> -#ifdef LZO
> - if (!(dd->flags & LZO_SUPPORTED)) {
> - if (lzo_init() == LZO_E_OK)
> - dd->flags |= LZO_SUPPORTED;
> - else
> - return 0;
> - }
> decompressor = (void *)&lzorle_decompress_safe;
> -#else
> - error(WARNING,
> - "zram decompress error: this executable needs to be
built"
> - " with lzo-rle library\n");
> - return 0;
> -#endif
> } else { /* todo: support more compressor */
> error(WARNING, "only the lzo compressor is
supported\n");
> return 0;
>
> --- a/lzorle_decompress.c
> +++ b/lzorle_decompress.c
> @@ -50,16 +50,18 @@ int lzorle_decompress_safe(const unsigned char *in, unsigned long
in_len,
>
> unsigned char bitstream_version;
>
> - bool efficient_unaligned_access;
> + static int efficient_unaligned_access = -1;
>
> + if (efficient_unaligned_access == -1) {
> #if defined(ARM) || defined(ARM64) || defined(X86) || defined(X86_64) ||
defined(PPC) || defined(PPC64) || defined(S390)|| defined(S390X)
> - efficient_unaligned_access = true;
> + efficient_unaligned_access = TRUE;
> #else
> - efficient_unaligned_access = false;
> + efficient_unaligned_access = FALSE;
> #endif
>
> - if (kt->ikconfig_flags & IKCONFIG_AVAIL)
> - efficient_unaligned_access =
(get_kernel_config("CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS", NULL) ==
IKCONFIG_Y);
> + if ((kt->ikconfig_flags & IKCONFIG_AVAIL) &&
get_kernel_config("CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS", NULL) ==
IKCONFIG_Y)
> + efficient_unaligned_access = TRUE;
> + }
>
>
> --
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