Static analyzer can not see balanced locking if the lock is acquired and
released conditionally.
context imbalance in 'uart_stop' - unexpected unlock
context imbalance in 'uart_start' - different lock contexts for basic block
context imbalance in 'uart_port_startup' - different lock contexts for basic block
context imbalance in 'uart_shutdown' - different lock contexts for basic block
context imbalance in 'uart_put_char' - different lock contexts for basic block
context imbalance in 'uart_write' - different lock contexts for basic block
context imbalance in 'uart_write_room' - different lock contexts for basic block
context imbalance in 'uart_chars_in_buffer' - different lock contexts for basic block
context imbalance in 'uart_flush_buffer' - different lock contexts for basic block
Get rid of macros and implement their functionality in place. This will also
help to enable runtime PM in cleaner way later on.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
drivers/tty/serial/serial_core.c | 106 +++++++++++++++++--------------
1 file changed, 58 insertions(+), 48 deletions(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 57840cf90388..b566127345c2 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -69,23 +69,6 @@ static inline void uart_port_deref(struct uart_port *uport)
wake_up(&uport->state->remove_wait);
}
-#define uart_port_lock(state, flags) \
- ({ \
- struct uart_port *__uport = uart_port_ref(state); \
- if (__uport) \
- spin_lock_irqsave(&__uport->lock, flags); \
- __uport; \
- })
-
-#define uart_port_unlock(uport, flags) \
- ({ \
- struct uart_port *__uport = uport; \
- if (__uport) { \
- spin_unlock_irqrestore(&__uport->lock, flags); \
- uart_port_deref(__uport); \
- } \
- })
-
static inline struct uart_port *uart_port_check(struct uart_state *state)
{
lockdep_assert_held(&state->port.mutex);
@@ -113,10 +96,14 @@ static void uart_stop(struct tty_struct *tty)
struct uart_port *port;
unsigned long flags;
- port = uart_port_lock(state, flags);
- if (port)
- port->ops->stop_tx(port);
- uart_port_unlock(port, flags);
+ port = uart_port_ref(state);
+ if (!port)
+ return;
+
+ spin_lock_irqsave(&port->lock, flags);
+ port->ops->stop_tx(port);
+ spin_unlock_irqrestore(&port->lock, flags);
+ uart_port_deref(port);
}
static void __uart_start(struct tty_struct *tty)
@@ -134,9 +121,14 @@ static void uart_start(struct tty_struct *tty)
struct uart_port *port;
unsigned long flags;
- port = uart_port_lock(state, flags);
+ port = uart_port_ref(state);
+ if (!port)
+ return;
+
+ spin_lock_irqsave(&port->lock, flags);
__uart_start(tty);
- uart_port_unlock(port, flags);
+ spin_unlock_irqrestore(&port->lock, flags);
+ uart_port_deref(port);
}
static void
@@ -186,7 +178,7 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
{
struct uart_port *uport = uart_port_check(state);
unsigned long page;
- unsigned long flags = 0;
+ unsigned long flags;
int retval = 0;
if (uport->type == PORT_UNKNOWN)
@@ -205,13 +197,14 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
if (!page)
return -ENOMEM;
- uart_port_lock(state, flags);
+ spin_lock_irqsave(&uport->lock, flags);
if (!state->xmit.buf) {
state->xmit.buf = (unsigned char *) page;
uart_circ_clear(&state->xmit);
- uart_port_unlock(uport, flags);
+ spin_unlock_irqrestore(&uport->lock, flags);
} else {
- uart_port_unlock(uport, flags);
+ spin_unlock_irqrestore(&uport->lock, flags);
+
/*
* Do not free() the page under the port lock, see
* uart_shutdown().
@@ -276,8 +269,8 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
{
struct uart_port *uport = uart_port_check(state);
struct tty_port *port = &state->port;
- unsigned long flags = 0;
char *xmit_buf = NULL;
+ unsigned long flags;
/*
* Set the TTY IO error marker
@@ -311,12 +304,12 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
* Do not free() the transmit buffer page under the port lock since
* this can create various circular locking scenarios. For instance,
* console driver may need to allocate/free a debug object, which
- * can endup in printk() recursion.
+ * can end up in printk() recursion.
*/
- uart_port_lock(state, flags);
+ spin_lock_irqsave(&uport->lock, flags);
xmit_buf = state->xmit.buf;
state->xmit.buf = NULL;
- uart_port_unlock(uport, flags);
+ spin_unlock_irqrestore(&uport->lock, flags);
if (xmit_buf)
free_page((unsigned long)xmit_buf);
@@ -553,19 +546,19 @@ static int uart_put_char(struct tty_struct *tty, unsigned char c)
unsigned long flags;
int ret = 0;
- circ = &state->xmit;
- port = uart_port_lock(state, flags);
- if (!circ->buf) {
- uart_port_unlock(port, flags);
+ port = uart_port_ref(state);
+ if (!port)
return 0;
- }
- if (port && uart_circ_chars_free(circ) != 0) {
+ spin_lock_irqsave(&port->lock, flags);
+ circ = &state->xmit;
+ if (circ->buf && uart_circ_chars_free(circ) != 0) {
circ->buf[circ->head] = c;
circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1);
ret = 1;
}
- uart_port_unlock(port, flags);
+ spin_unlock_irqrestore(&port->lock, flags);
+ uart_port_deref(port);
return ret;
}
@@ -592,13 +585,17 @@ static int uart_write(struct tty_struct *tty,
return -EL3HLT;
}
- port = uart_port_lock(state, flags);
+ port = uart_port_ref(state);
+ if (!port)
+ return 0;
+
+ spin_lock_irqsave(&port->lock, flags);
circ = &state->xmit;
if (!circ->buf) {
- uart_port_unlock(port, flags);
+ spin_unlock_irqrestore(&port->lock, flags);
+ uart_port_deref(port);
return 0;
}
-
while (port) {
c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
if (count < c)
@@ -613,7 +610,8 @@ static int uart_write(struct tty_struct *tty,
}
__uart_start(tty);
- uart_port_unlock(port, flags);
+ spin_unlock_irqrestore(&port->lock, flags);
+ uart_port_deref(port);
return ret;
}
@@ -624,9 +622,14 @@ static int uart_write_room(struct tty_struct *tty)
unsigned long flags;
int ret;
- port = uart_port_lock(state, flags);
+ port = uart_port_ref(state);
+ if (!port)
+ return uart_circ_chars_free(&state->xmit);
+
+ spin_lock_irqsave(&port->lock, flags);
ret = uart_circ_chars_free(&state->xmit);
- uart_port_unlock(port, flags);
+ spin_unlock_irqrestore(&port->lock, flags);
+ uart_port_deref(port);
return ret;
}
@@ -637,9 +640,14 @@ static int uart_chars_in_buffer(struct tty_struct *tty)
unsigned long flags;
int ret;
- port = uart_port_lock(state, flags);
+ port = uart_port_ref(state);
+ if (!port)
+ return uart_circ_chars_pending(&state->xmit);
+
+ spin_lock_irqsave(&port->lock, flags);
ret = uart_circ_chars_pending(&state->xmit);
- uart_port_unlock(port, flags);
+ spin_unlock_irqrestore(&port->lock, flags);
+ uart_port_deref(port);
return ret;
}
@@ -660,13 +668,15 @@ static void uart_flush_buffer(struct tty_struct *tty)
pr_debug("uart_flush_buffer(%d) called\n", tty->index);
- port = uart_port_lock(state, flags);
+ port = uart_port_ref(state);
if (!port)
return;
+ spin_lock_irqsave(&port->lock, flags);
uart_circ_clear(&state->xmit);
if (port->ops->flush_buffer)
port->ops->flush_buffer(port);
- uart_port_unlock(port, flags);
+ spin_unlock_irqrestore(&port->lock, flags);
+ uart_port_deref(port);
tty_port_tty_wakeup(&state->port);
}
--
2.27.0.rc2
