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tty: serial: msm: Fix sysrq spinlock recursion on non-DM
author
Stephen Boyd
<sboyd@codeaurora.org>
Wed, 29 Oct 2014 18:14:37 +0000
(11:14 -0700)
committer
Greg Kroah-Hartman
<gregkh@linuxfoundation.org>
Thu, 6 Nov 2014 22:57:22 +0000
(14:57 -0800)
The handle_rx() path calls uart_handle_sysrq_char() with the port
lock held. This causes a spinlock recursion. Release and
reacquire the lock here to avoid this.
BUG: spinlock recursion on CPU#0, swapper/0
lock: msm_uart_ports+0x1e0/0x2d0, .magic:
dead4ead
, .owner: swapper/0, .owner_cpu: 0
CPU: 0 PID: 0 Comm: swapper Not tainted
3.17.0-rc7-00012-gb38ee8265941
#69
[<
c0013964
>] (unwind_backtrace) from [<
c0011f74
>] (show_stack+0x10/0x14)
[<
c0011f74
>] (show_stack) from [<
c004ed1c
>] (do_raw_spin_lock+0x11c/0x13c)
[<
c004ed1c
>] (do_raw_spin_lock) from [<
c02d44c0
>] (msm_console_write+0x78/0x188)
[<
c02d44c0
>] (msm_console_write) from [<
c0052880
>] (call_console_drivers.constprop.22+0xb4/0x144)
[<
c0052880
>] (call_console_drivers.constprop.22) from [<
c0053570
>] (console_unlock+0x27c/0x4ac)
[<
c0053570
>] (console_unlock) from [<
c0053bb4
>] (vprintk_emit+0x1f4/0x5a8)
[<
c0053bb4
>] (vprintk_emit) from [<
c04ad0ac
>] (printk+0x30/0x40)
[<
c04ad0ac
>] (printk) from [<
c02c2990
>] (__handle_sysrq+0x58/0x1b8)
[<
c02c2990
>] (__handle_sysrq) from [<
c02d41b0
>] (msm_irq+0x694/0x6f8)
[<
c02d41b0
>] (msm_irq) from [<
c0055740
>] (handle_irq_event_percpu+0x58/0x270)
[<
c0055740
>] (handle_irq_event_percpu) from [<
c0055994
>] (handle_irq_event+0x3c/0x5c)
[<
c0055994
>] (handle_irq_event) from [<
c0057e84
>] (handle_level_irq+0x9c/0x138)
[<
c0057e84
>] (handle_level_irq) from [<
c005509c
>] (generic_handle_irq+0x24/0x38)
[<
c005509c
>] (generic_handle_irq) from [<
c000f730
>] (handle_IRQ+0x44/0xb0)
[<
c000f730
>] (handle_IRQ) from [<
c0008518
>] (msm_vic_handle_irq+0x44/0x64)
[<
c0008518
>] (msm_vic_handle_irq) from [<
c04b5ac4
>] (__irq_svc+0x44/0x7c)
Exception stack(0xc0719f68 to 0xc0719fb0)
9f60:
00000001
00000001
00000000
c0722938
c0718000
c0769acc
9f80:
00000000
c0720098
c0769305
4117b362
c0769acc
00000000
01000000
c0719fb0
9fa0:
c004cab0
c000f880
20000013
ffffffff
[<
c04b5ac4
>] (__irq_svc) from [<
c000f880
>] (arch_cpu_idle+0x20/0x30)
[<
c000f880
>] (arch_cpu_idle) from [<
c004691c
>] (cpu_startup_entry+0xf4/0x23c)
[<
c004691c
>] (cpu_startup_entry) from [<
c06d8b70
>] (start_kernel+0x32c/0x394)
Cc: Frank Rowand <frank.rowand@sonymobile.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/serial/msm_serial.c
patch
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blob
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history
diff --git
a/drivers/tty/serial/msm_serial.c
b/drivers/tty/serial/msm_serial.c
index
4b6c783
..
cedcc36
100644
(file)
--- a/
drivers/tty/serial/msm_serial.c
+++ b/
drivers/tty/serial/msm_serial.c
@@
-174,6
+174,7
@@
static void handle_rx(struct uart_port *port)
while ((sr = msm_read(port, UART_SR)) & UART_SR_RX_READY) {
unsigned int c;
char flag = TTY_NORMAL;
+ int sysrq;
c = msm_read(port, UART_RF);
@@
-195,7
+196,10
@@
static void handle_rx(struct uart_port *port)
else if (sr & UART_SR_PAR_FRAME_ERR)
flag = TTY_FRAME;
- if (!uart_handle_sysrq_char(port, c))
+ spin_unlock(&port->lock);
+ sysrq = uart_handle_sysrq_char(port, c);
+ spin_lock(&port->lock);
+ if (!sysrq)
tty_insert_flip_char(tport, c, flag);
}