With smp CPUs have to compete for sclp. Let's add some locking, so
they execute sclp calls in an orderly fashion.
Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
---
lib/s390x/sclp.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
index 817c692..947a533 100644
--- a/lib/s390x/sclp.c
+++ b/lib/s390x/sclp.c
@@ -15,6 +15,7 @@
#include <asm/arch_def.h>
#include <asm/interrupt.h>
#include <asm/barrier.h>
+#include <asm/spinlock.h>
#include "sclp.h"
#include <alloc_phys.h>
@@ -26,6 +27,7 @@ static uint64_t ram_size;
char _sccb[PAGE_SIZE] __attribute__((__aligned__(4096)));
static volatile bool sclp_busy;
+static struct spinlock sclp_lock;
static void mem_init(phys_addr_t mem_end)
{
@@ -48,7 +50,9 @@ static void sclp_setup_int(void)
void sclp_handle_ext(void)
{
ctl_clear_bit(0, 9);
+ spin_lock(&sclp_lock);
sclp_busy = false;
+ spin_unlock(&sclp_lock);
}
void sclp_wait_busy(void)
@@ -59,7 +63,19 @@ void sclp_wait_busy(void)
void sclp_mark_busy(void)
{
+ /*
+ * With multiple CPUs we might need to wait for another CPU's
+ * request before grabbing the busy indication.
+ */
+retry_wait:
+ sclp_wait_busy();
+ spin_lock(&sclp_lock);
+ if (sclp_busy) {
+ spin_unlock(&sclp_lock);
+ goto retry_wait;
+ }
sclp_busy = true;
+ spin_unlock(&sclp_lock);
}
static void sclp_read_scp_info(ReadInfo *ri, int length)
--
2.14.3
