| Message ID | 20240319180239.69765-1-emil.kronborg@protonmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] serial: mxs-auart: add spinlock around changing cts state | expand |
On Tue, Mar 19, 2024 at 06:02:47PM +0000, Emil Kronborg wrote: > The uart_handle_cts_change() function in serial_core expects the caller > to hold uport->lock. For example, I have seen the below kernel splat, > when the Bluetooth driver is loaded on an i.MX28 board. > > [ 85.119255] ------------[ cut here ]------------ > [ 85.124413] WARNING: CPU: 0 PID: 27 at /drivers/tty/serial/serial_core.c:3453 uart_handle_cts_change+0xb4/0xec > [ 85.134694] Modules linked in: hci_uart bluetooth ecdh_generic ecc wlcore_sdio configfs > [ 85.143314] CPU: 0 PID: 27 Comm: kworker/u3:0 Not tainted 6.6.3-00021-gd62a2f068f92 #1 > [ 85.151396] Hardware name: Freescale MXS (Device Tree) > [ 85.156679] Workqueue: hci0 hci_power_on [bluetooth] > (...) > [ 85.191765] uart_handle_cts_change from mxs_auart_irq_handle+0x380/0x3f4 > [ 85.198787] mxs_auart_irq_handle from __handle_irq_event_percpu+0x88/0x210 > (...) > > Cc: stable@vger.kernel.org # v6.1+ > Fixes: 4d90bb147ef6 ("serial: core: Document and assert lock requirements for irq helpers") > Signed-off-by: Emil Kronborg <emil.kronborg@protonmail.com> Reviewed-by: Frank Li <Frank.Li@nxp.com> > --- > Changes in v2: > - Add more of the stack trace to show why the lock is necessary. Note > that i removed some unrelated noise for unwinding, showing and dumping > the stack trace. > - Add Fixes tag. Note that this commit do not fix 4d90bb147ef6 ("serial: > core: Document and assert lock requirements for irq helpers") as such, > but it was the closest commit I could find that makes sense. > - Cc stable. Commit b0af4bcb4946 ("serial: core: Provide port lock > wrappers") is a prerequisite. Therefore, v6.1+. > > drivers/tty/serial/mxs-auart.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c > index 4749331fe618..1e8853eae504 100644 > --- a/drivers/tty/serial/mxs-auart.c > +++ b/drivers/tty/serial/mxs-auart.c > @@ -1086,11 +1086,13 @@ static void mxs_auart_set_ldisc(struct uart_port *port, > > static irqreturn_t mxs_auart_irq_handle(int irq, void *context) > { > - u32 istat; > + u32 istat, stat; > struct mxs_auart_port *s = context; > u32 mctrl_temp = s->mctrl_prev; > - u32 stat = mxs_read(s, REG_STAT); > > + uart_port_lock(&s->port); > + > + stat = mxs_read(s, REG_STAT); > istat = mxs_read(s, REG_INTR); > > /* ack irq */ > @@ -1126,6 +1128,8 @@ static irqreturn_t mxs_auart_irq_handle(int irq, void *context) > istat &= ~AUART_INTR_TXIS; > } > > + uart_port_unlock(&s->port); > + > return IRQ_HANDLED; > } > > -- > 2.44.0 > >
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c index 4749331fe618..1e8853eae504 100644 --- a/drivers/tty/serial/mxs-auart.c +++ b/drivers/tty/serial/mxs-auart.c @@ -1086,11 +1086,13 @@ static void mxs_auart_set_ldisc(struct uart_port *port, static irqreturn_t mxs_auart_irq_handle(int irq, void *context) { - u32 istat; + u32 istat, stat; struct mxs_auart_port *s = context; u32 mctrl_temp = s->mctrl_prev; - u32 stat = mxs_read(s, REG_STAT); + uart_port_lock(&s->port); + + stat = mxs_read(s, REG_STAT); istat = mxs_read(s, REG_INTR); /* ack irq */ @@ -1126,6 +1128,8 @@ static irqreturn_t mxs_auart_irq_handle(int irq, void *context) istat &= ~AUART_INTR_TXIS; } + uart_port_unlock(&s->port); + return IRQ_HANDLED; }
The uart_handle_cts_change() function in serial_core expects the caller to hold uport->lock. For example, I have seen the below kernel splat, when the Bluetooth driver is loaded on an i.MX28 board. [ 85.119255] ------------[ cut here ]------------ [ 85.124413] WARNING: CPU: 0 PID: 27 at /drivers/tty/serial/serial_core.c:3453 uart_handle_cts_change+0xb4/0xec [ 85.134694] Modules linked in: hci_uart bluetooth ecdh_generic ecc wlcore_sdio configfs [ 85.143314] CPU: 0 PID: 27 Comm: kworker/u3:0 Not tainted 6.6.3-00021-gd62a2f068f92 #1 [ 85.151396] Hardware name: Freescale MXS (Device Tree) [ 85.156679] Workqueue: hci0 hci_power_on [bluetooth] (...) [ 85.191765] uart_handle_cts_change from mxs_auart_irq_handle+0x380/0x3f4 [ 85.198787] mxs_auart_irq_handle from __handle_irq_event_percpu+0x88/0x210 (...) Cc: stable@vger.kernel.org # v6.1+ Fixes: 4d90bb147ef6 ("serial: core: Document and assert lock requirements for irq helpers") Signed-off-by: Emil Kronborg <emil.kronborg@protonmail.com> --- Changes in v2: - Add more of the stack trace to show why the lock is necessary. Note that i removed some unrelated noise for unwinding, showing and dumping the stack trace. - Add Fixes tag. Note that this commit do not fix 4d90bb147ef6 ("serial: core: Document and assert lock requirements for irq helpers") as such, but it was the closest commit I could find that makes sense. - Cc stable. Commit b0af4bcb4946 ("serial: core: Provide port lock wrappers") is a prerequisite. Therefore, v6.1+. drivers/tty/serial/mxs-auart.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)