block: fix linkage problem with blk_iopoll and !CONFIG_BLOCK
kernel/built-in.o:(.data+0x17b0): undefined reference to `blk_iopoll_enabled'
Since the extern declaration makes the compile work, but the actual
symbol is missing when block/blk-iopoll.o isn't linked in.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 6bb59f7..1a631ba 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -91,7 +91,9 @@
#ifdef CONFIG_RCU_TORTURE_TEST
extern int rcutorture_runnable;
#endif /* #ifdef CONFIG_RCU_TORTURE_TEST */
+#ifdef CONFIG_BLOCK
extern int blk_iopoll_enabled;
+#endif
/* Constants used for minimum and maximum */
#ifdef CONFIG_DETECT_SOFTLOCKUP
@@ -998,6 +1000,7 @@
.proc_handler = &proc_dointvec,
},
#endif
+#ifdef CONFIG_BLOCK
{
.ctl_name = CTL_UNNUMBERED,
.procname = "blk_iopoll",
@@ -1006,6 +1009,7 @@
.mode = 0644,
.proc_handler = &proc_dointvec,
},
+#endif
/*
* NOTE: do not add new entries to this table unless you have read
* Documentation/sysctl/ctl_unnumbered.txt