[Skiboot] [RFC PATCH] FSP: Solidify timeout poll code

[Ananth N Mavinakayanahalli]

Prevent multiple callers to the timeout poller.
Add more error checking while there.

Signed-off-by: Ananth N Mavinakayanahalli <ananth at in.ibm.com>
---
 hw/fsp/fsp.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/hw/fsp/fsp.c b/hw/fsp/fsp.c
index 8a73f2c..bc5e3e7 100644
--- a/hw/fsp/fsp.c
+++ b/hw/fsp/fsp.c
@@ -91,6 +91,7 @@ static void *fsp_inbound_buf = NULL;
 static u32 fsp_inbound_off;
 
 static struct lock fsp_lock = LOCK_UNLOCKED;
+static struct lock fsp_timeout_poller_lock = LOCK_UNLOCKED;
 
 static u64 fsp_cmdclass_resp_bitmask;
 static u64 timeout_timer;
@@ -1904,7 +1905,7 @@ bool fsp_present(void)
 	return first_fsp != NULL;
 }
 
-static void fsp_timeout_poll(void *data __unused)
+static void __fsp_timeout_poll(void *data __unused)
 {
 	u64 now = mftb();
 	u64 timeout_val = 0;
@@ -1952,6 +1953,8 @@ static void fsp_timeout_poll(void *data __unused)
 				goto next_bit;
 			}
 			req = list_top(&cmdclass->msgq,	struct fsp_msg, link);
+			if (!req)
+				goto next_bit;
 			w0 = req->word0;
 			w1 = req->word1;
 			mstate = req->state;
@@ -1976,6 +1979,14 @@ static void fsp_timeout_poll(void *data __unused)
 	}
 }
 
+static void fsp_timeout_poll(void *data __unused)
+{
+	if (try_lock(&fsp_timeout_poller_lock)) {
+		__fsp_timeout_poll(data);
+		unlock(&fsp_timeout_poller_lock);
+	}
+}
+
 void fsp_opl(void)
 {
 	struct dt_node *iplp;