zcache/tmem: Better error checking on frontswap_register_ops return value.
In the past it either used to be NULL or the "older" backend. Now we
also return -Exx error codes.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Bob Liu <lliubbo@gmail.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Andor Daam <andor.daam@googlemail.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Florian Schmaus <fschmaus@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Stefan Hengelein <ilendir@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
index 6bd4ebb..118602f 100644
--- a/drivers/staging/zcache/zcache-main.c
+++ b/drivers/staging/zcache/zcache-main.c
@@ -1886,8 +1886,11 @@
namestr, frontswap_has_exclusive_gets,
!disable_frontswap_ignore_nonactive);
#endif
- if (old_ops != NULL)
+ if (IS_ERR(old_ops) || old_ops) {
+ if (IS_ERR(old_ops))
+ return PTR_RET(old_ops);
pr_warn("%s: frontswap_ops overridden\n", namestr);
+ }
}
if (ramster_enabled)
ramster_init(!disable_cleancache, !disable_frontswap,
diff --git a/drivers/xen/tmem.c b/drivers/xen/tmem.c
index 8adde8e..e3600be 100644
--- a/drivers/xen/tmem.c
+++ b/drivers/xen/tmem.c
@@ -397,8 +397,11 @@
frontswap_register_ops(&tmem_frontswap_ops);
tmem_frontswap_poolid = -1;
- if (old_ops)
+ if (IS_ERR(old_ops) || old_ops) {
+ if (IS_ERR(old_ops))
+ return PTR_ERR(old_ops);
s = " (WARNING: frontswap_ops overridden)";
+ }
printk(KERN_INFO "frontswap enabled, RAM provided by "
"Xen Transcendent Memory%s\n", s);
}