| Message ID | 20220506213324.470461-1-john.ogness@linutronix.de |
|---|---|
| State | Accepted |
| Commit | aabdbb1b7a5819e18c403334a31fb0cc2c06ad41 |
| Headers | show |
| Series | [next,v1] serial: msm_serial: disable interrupts in __msm_console_write() | expand |
On Fri 2022-05-06 23:39:24, John Ogness wrote: > __msm_console_write() assumes that interrupts are disabled, but > with threaded console printers it is possible that the write() > callback of the console is called with interrupts enabled. IMHO, it would be nice to include the lockdep splat from https://lore.kernel.org/r/bb5cadc3-0940-7f5c-7a1b-8120ddac9039@samsung.com > Explicitly disable interrupts using local_irq_save() to preserve > the assumed context. > > Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> > Signed-off-by: John Ogness <john.ogness@linutronix.de> Otherwise, it looks good to me: Reviewed-by: Petr Mladek <pmladek@suse.com> > Note: I checked the other serial drivers and this was the only > one that assumed interrupts off for write(). Great. Best Regards, Petr > drivers/tty/serial/msm_serial.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c > index 23c94b927776..e676ec761f18 100644 > --- a/drivers/tty/serial/msm_serial.c > +++ b/drivers/tty/serial/msm_serial.c > @@ -1599,6 +1599,7 @@ static inline struct uart_port *msm_get_port_from_line(unsigned int line) > static void __msm_console_write(struct uart_port *port, const char *s, > unsigned int count, bool is_uartdm) > { > + unsigned long flags; > int i; > int num_newlines = 0; > bool replaced = false; > @@ -1616,6 +1617,8 @@ static void __msm_console_write(struct uart_port *port, const char *s, > num_newlines++; > count += num_newlines; > > + local_irq_save(flags); > + > if (port->sysrq) > locked = 0; > else if (oops_in_progress) > @@ -1661,6 +1664,8 @@ static void __msm_console_write(struct uart_port *port, const char *s, > > if (locked) > spin_unlock(&port->lock); > + > + local_irq_restore(flags); > } > > static void msm_console_write(struct console *co, const char *s, > > base-commit: 38a288f5941ef03752887ad86f2d85442358c99a > -- > 2.30.2
diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index 23c94b927776..e676ec761f18 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -1599,6 +1599,7 @@ static inline struct uart_port *msm_get_port_from_line(unsigned int line) static void __msm_console_write(struct uart_port *port, const char *s, unsigned int count, bool is_uartdm) { + unsigned long flags; int i; int num_newlines = 0; bool replaced = false; @@ -1616,6 +1617,8 @@ static void __msm_console_write(struct uart_port *port, const char *s, num_newlines++; count += num_newlines; + local_irq_save(flags); + if (port->sysrq) locked = 0; else if (oops_in_progress) @@ -1661,6 +1664,8 @@ static void __msm_console_write(struct uart_port *port, const char *s, if (locked) spin_unlock(&port->lock); + + local_irq_restore(flags); } static void msm_console_write(struct console *co, const char *s,
__msm_console_write() assumes that interrupts are disabled, but with threaded console printers it is possible that the write() callback of the console is called with interrupts enabled. Explicitly disable interrupts using local_irq_save() to preserve the assumed context. Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: John Ogness <john.ogness@linutronix.de> --- Note: I checked the other serial drivers and this was the only one that assumed interrupts off for write(). drivers/tty/serial/msm_serial.c | 5 +++++ 1 file changed, 5 insertions(+) base-commit: 38a288f5941ef03752887ad86f2d85442358c99a