[PATCH resend] staging: zcache: fix "zcache=" kernel parameter

Bartlomiej Zolnierkiewicz b.zolnierkie at samsung.com
Mon Jul 29 10:25:20 UTC 2013

From: Piotr Sarna <p.sarna at partner.samsung.com>

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 Rodriguez):


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 at partner.samsung.com>
[bzolnier: updated patch description]
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie at samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Acked-by: Michal Hocko <mhocko at suse.cz>
Cc: Cristian Rodriguez <crrodriguez at opensuse.org>
Cc: Bob Liu <bob.liu at oracle.com>
 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)
 	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",
-		goto out;
+			ret = 1;
+			goto out;
+		}
 	if (!ret)
 		strcpy(zcache_comp_name, "lzo");

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