| Message ID | 20220405033854.110374-2-jaewon02.kim@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | tty: serial: samsung: add spin_lock in console_write | expand |
On Tue, Apr 05, 2022 at 12:38:54PM +0900, Jaewon Kim wrote: > The console_write and IRQ handler can run concurrently. > Problems may occurs console_write is continuously executed while > the IRQ handler is running. > > Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com> > --- > drivers/tty/serial/samsung_tty.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) What commit does this fix? > > diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c > index e1585fbae909..d362e8e114f1 100644 > --- a/drivers/tty/serial/samsung_tty.c > +++ b/drivers/tty/serial/samsung_tty.c > @@ -2480,12 +2480,26 @@ s3c24xx_serial_console_write(struct console *co, const char *s, > unsigned int count) > { > unsigned int ucon = rd_regl(cons_uart, S3C2410_UCON); > + unsigned long flags; > + int locked = 1; bool? > > /* not possible to xmit on unconfigured port */ > if (!s3c24xx_port_configured(ucon)) > return; > > + local_irq_save(flags); > + if (cons_uart->sysrq) > + locked = 0; > + else if (oops_in_progress) > + locked = spin_trylock(&cons_uart->lock); > + else > + spin_lock(&cons_uart->lock); > + > uart_console_write(cons_uart, s, count, s3c24xx_serial_console_putchar); > + > + if (locked) > + spin_unlock(&cons_uart->lock); > + local_irq_restore(flags); Why is irq_save required as well as a spinlock? thanks, greg k-h
Hello On 22. 4. 5. 14:01, Greg Kroah-Hartman wrote: > On Tue, Apr 05, 2022 at 12:38:54PM +0900, Jaewon Kim wrote: > > The console_write and IRQ handler can run concurrently. > > Problems may occurs console_write is continuously executed while the > > IRQ handler is running. > > > > Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com> > > --- > > drivers/tty/serial/samsung_tty.c | 14 ++++++++++++++ > > 1 file changed, 14 insertions(+) > > What commit does this fix? This is not an issue caused by anohter commits. There was potential issue from the beginning. Other drivers were fixed, but samsung_tty was not. PL011 patch : https://lkml.org/lkml/2012/2/1/495 > > > > > diff --git a/drivers/tty/serial/samsung_tty.c > > b/drivers/tty/serial/samsung_tty.c > > index e1585fbae909..d362e8e114f1 100644 > > --- a/drivers/tty/serial/samsung_tty.c > > +++ b/drivers/tty/serial/samsung_tty.c > > @@ -2480,12 +2480,26 @@ s3c24xx_serial_console_write(struct console *co, const char *s, > > unsigned int count) > > { > > unsigned int ucon = rd_regl(cons_uart, S3C2410_UCON); > > + unsigned long flags; > > + int locked = 1; > > bool? It is return value of spin_trylock() I used int because mose drivers used int. If you guide to change int to bool, I will change it. > > > > > /* not possible to xmit on unconfigured port */ > > if (!s3c24xx_port_configured(ucon)) > > return; > > > > + local_irq_save(flags); > > + if (cons_uart->sysrq) > > + locked = 0; > > + else if (oops_in_progress) > > + locked = spin_trylock(&cons_uart->lock); > > + else > > + spin_lock(&cons_uart->lock); > > + > > uart_console_write(cons_uart, s, count, > > s3c24xx_serial_console_putchar); > > + > > + if (locked) > > + spin_unlock(&cons_uart->lock); > > + local_irq_restore(flags); > > Why is irq_save required as well as a spinlock? No special reason. I will change spin_trylock() -? spin_trylock_irqsave(). spin_lock -> spin_lock_irqsave(). And, remove local_irq_save/restore. It looks more clean. > > thanks, > > greg k-h Thanks Jaewon Kim
diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c index e1585fbae909..d362e8e114f1 100644 --- a/drivers/tty/serial/samsung_tty.c +++ b/drivers/tty/serial/samsung_tty.c @@ -2480,12 +2480,26 @@ s3c24xx_serial_console_write(struct console *co, const char *s, unsigned int count) { unsigned int ucon = rd_regl(cons_uart, S3C2410_UCON); + unsigned long flags; + int locked = 1; /* not possible to xmit on unconfigured port */ if (!s3c24xx_port_configured(ucon)) return; + local_irq_save(flags); + if (cons_uart->sysrq) + locked = 0; + else if (oops_in_progress) + locked = spin_trylock(&cons_uart->lock); + else + spin_lock(&cons_uart->lock); + uart_console_write(cons_uart, s, count, s3c24xx_serial_console_putchar); + + if (locked) + spin_unlock(&cons_uart->lock); + local_irq_restore(flags); } /* Shouldn't be __init, as it can be instantiated from other module */
The console_write and IRQ handler can run concurrently. Problems may occurs console_write is continuously executed while the IRQ handler is running. Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com> --- drivers/tty/serial/samsung_tty.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)