On Wed 24-07-13 19:04:14, Bartlomiej Zolnierkiewicz wrote:
> From: Piotr Sarna <p.sarna@xxxxxxxxxxxxxxxxxxx>
> Subject: [PATCH] zcache: fix "zcache=" kernel parameter
>
> Commit 835f2f5 ("staging: zcache: enable zcache to be built/loaded as
> a module") introduced an incorrect handling of "zcache=" parameter.
>
> Inside zcache_comp_init() function, zcache_comp_name variable is
> checked for being empty. If not empty, the above variable is tested
> for being compatible with Crypto API. Unfortunately, after that
> function ends unconditionally (by the "goto out" directive) and returns:
> - non-zero value if verification succeeded, wrongly indicating an error
> - zero value if verification failed, falsely informing that function
> zcache_comp_init() ended properly.
>
> A solution to this problem is as following:
> 1. Move the "goto out" directive inside the "if (!ret)" statement
> 2. In case that crypto_has_comp() returned 0, change the value of ret
> to non-zero before "goto out" to indicate an error.
>
> This patch replaces an earlier one from Michal Hocko (based on report
> from Cristian Rodríguez):
>
> http://permalink.gmane.org/gmane.linux.kernel.mm/102484
>
> It also addressed the same issue but didn't fix the zcache_comp_init()
> for case when the compressor data passed to "zcache=" option was invalid
> or unsupported.
>
> Signed-off-by: Piotr Sarna <p.sarna@xxxxxxxxxxxxxxxxxxx>
> [bzolnier: updated patch description]
> Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Cc: Cristian Rodríguez <crrodriguez@xxxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxx>
> Cc: Bob Liu <bob.liu@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Thanks!
> ---
> drivers/staging/zcache/zcache-main.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
> index dcceed2..81972fa 100644
> --- a/drivers/staging/zcache/zcache-main.c
> +++ b/drivers/staging/zcache/zcache-main.c
> @@ -1811,10 +1811,12 @@ static int zcache_comp_init(void)
> #else
> if (*zcache_comp_name != '\0') {
> ret = crypto_has_comp(zcache_comp_name, 0, 0);
> - if (!ret)
> + if (!ret) {
> pr_info("zcache: %s not supported\n",
> zcache_comp_name);
> - goto out;
> + ret = 1;
> + goto out;
> + }
> }
> if (!ret)
> strcpy(zcache_comp_name, "lzo");
> --
> 1.7.9.5
>
>
>
--
Michal Hocko
SUSE Labs
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