Change in coreboot[master]: lib/thread: Verify threads are initialized before yielding

[Raul Rangel (Code Review)]

Raul Rangel has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/56318 )

Change subject: lib/thread: Verify threads are initialized before yielding
......................................................................

lib/thread: Verify threads are initialized before yielding

In hardwaremain.c we call console_init before threads_initialize. Part
of setting up the uart requires calling udelay which then calls
thread_yield_microseconds. Since threads have not been setup, trying to
yield will result in bad things happening. This change guards the thread
methods by making current_thread return NULL if the structures have not
been initialized.

BUG=b:179699789
TEST=Ramstage no longer hangs with serial enabled

Signed-off-by: Raul E Rangel 
Change-Id: If9e1eedfaebe584901d2937c8aa24e158706fa43
---
M src/lib/thread.c
1 file changed, 7 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/18/56318/1

diff --git a/src/lib/thread.c b/src/lib/thread.c
index e2280c6..782a63e 100644
--- a/src/lib/thread.c
+++ b/src/lib/thread.c
@@ -9,6 +9,8 @@
 #include <thread.h>
 #include <timer.h>

+static bool initialized;
+
 static void idle_thread_init(void);

/* There needs to be at least one thread to run the ramstate state machine. */
@@ -40,6 +42,9 @@

static inline struct thread *current_thread(void)
 {
+	if (!initialized)
+		return NULL;
+
    return cpu_info_to_thread(cpu_info());
 }

@@ -265,6 +270,8 @@
    	free_thread(t);
    }

+	initialized = 1;
+
    idle_thread_init();
 }