The RAW console does not need writes to be atomic, so implement a
_nonatomic variant which does not take a spinlock. This API is used
in xmon, so the less locking thta's used, the better chance there is
that a crash can be debugged.
Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/include/asm/opal.h | 1 +
arch/powerpc/platforms/powernv/opal.c | 35 +++++++++++++++++++--------
drivers/tty/hvc/hvc_opal.c | 4 +--
3 files changed, 28 insertions(+), 12 deletions(-)
diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index bbff49fab0e5..66954d671831 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -303,6 +303,7 @@ extern void opal_configure_cores(void);
extern int opal_get_chars(uint32_t vtermno, char *buf, int count);
extern int opal_put_chars(uint32_t vtermno, const char *buf, int total_len);
+extern int opal_put_chars_nonatomic(uint32_t vtermno, const char *buf, int
total_len);
extern int opal_flush_console(uint32_t vtermno);
extern void hvc_opal_init_early(void);
diff --git a/arch/powerpc/platforms/powernv/opal.c
b/arch/powerpc/platforms/powernv/opal.c
index b05500a70f58..dc77fc57d1e9 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -344,9 +344,9 @@ int opal_get_chars(uint32_t vtermno, char *buf, int count)
return 0;
}
-int opal_put_chars(uint32_t vtermno, const char *data, int total_len)
+static int __opal_put_chars(uint32_t vtermno, const char *data, int total_len,
bool atomic)
{
- unsigned long flags;
+ unsigned long flags = 0 /* shut up gcc */;
int written;
__be64 olen;
s64 rc;
@@ -354,11 +354,8 @@ int opal_put_chars(uint32_t vtermno, const char *data, int
total_len)
if (!opal.entry)
return -ENODEV;
- /* We want put_chars to be atomic to avoid mangling of hvsi
- * packets. To do that, we first test for room and return
- * -EAGAIN if there isn't enough.
- */
- spin_lock_irqsave(&opal_write_lock, flags);
+ if (atomic)
+ spin_lock_irqsave(&opal_write_lock, flags);
rc = opal_console_write_buffer_space(vtermno, &olen);
if (rc || be64_to_cpu(olen) < total_len) {
/* Closed -> drop characters */
@@ -391,14 +388,18 @@ int opal_put_chars(uint32_t vtermno, const char *data,
int total_len)
written = be64_to_cpu(olen);
if (written < total_len) {
- /* Should not happen */
- pr_warn("atomic console write returned partial len=%d
written=%d\n", total_len, written);
+ if (atomic) {
+ /* Should not happen */
+ pr_warn("atomic console write returned partial "
+ "len=%d written=%d\n", total_len, written);
+ }
if (!written)
written = -EAGAIN;
}
out:
- spin_unlock_irqrestore(&opal_write_lock, flags);
+ if (atomic)
+ spin_unlock_irqrestore(&opal_write_lock, flags);
/* In the -EAGAIN case, callers loop, so we have to flush the console
* here in case they have interrupts off (and we don't want to wait
@@ -412,6 +413,20 @@ int opal_put_chars(uint32_t vtermno, const char *data, int
total_len)
return written;
}
+int opal_put_chars(uint32_t vtermno, const char *data, int total_len)
+{
+ /* We want put_chars to be atomic to avoid mangling of hvsi
+ * packets. To do that, we first test for room and return
+ * -EAGAIN if there isn't enough.
+ */
+ return __opal_put_chars(vtermno, data, total_len, true);
+}
+
+int opal_put_chars_nonatomic(uint32_t vtermno, const char *data, int total_len)
+{
+ return __opal_put_chars(vtermno, data, total_len, false);
+}
+
int opal_flush_console(uint32_t vtermno)
{
s64 rc;
diff --git a/drivers/tty/hvc/hvc_opal.c b/drivers/tty/hvc/hvc_opal.c
index af122ad7f06d..e151cfacf2a7 100644
--- a/drivers/tty/hvc/hvc_opal.c
+++ b/drivers/tty/hvc/hvc_opal.c
@@ -51,7 +51,7 @@ static u32 hvc_opal_boot_termno;
static const struct hv_ops hvc_opal_raw_ops = {
.get_chars = opal_get_chars,
- .put_chars = opal_put_chars,
+ .put_chars = opal_put_chars_nonatomic,
.notifier_add = notifier_add_irq,
.notifier_del = notifier_del_irq,
.notifier_hangup = notifier_hangup_irq,
@@ -269,7 +269,7 @@ static void udbg_opal_putc(char c)
do {
switch(hvc_opal_boot_priv.proto) {
case HV_PROTOCOL_RAW:
- count = opal_put_chars(termno, &c, 1);
+ count = opal_put_chars_nonatomic(termno, &c, 1);
break;
case HV_PROTOCOL_HVSI:
count = hvc_opal_hvsi_put_chars(termno, &c, 1);
--
2.17.0
