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| author | Stephen Boyd <sboyd@codeaurora.org> | 2014-10-29 11:14:37 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-11-06 14:57:22 -0800 |
| commit | 660beb0e94ad81cfcb6b7846606c0378b0152064 (patch) | |
| tree | 2f57e1d32d3051661284d5e6a5de665df8556f39 /drivers/tty/serial/msm_serial.c | |
| parent | 36a262782b045220bfccf89bd2c4d78cbe152c8e (diff) | |
| download | linux-660beb0e94ad81cfcb6b7846606c0378b0152064.tar.gz linux-660beb0e94ad81cfcb6b7846606c0378b0152064.tar.bz2 linux-660beb0e94ad81cfcb6b7846606c0378b0152064.zip | |
tty: serial: msm: Fix sysrq spinlock recursion on non-DM
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>
Diffstat (limited to 'drivers/tty/serial/msm_serial.c')
| -rw-r--r-- | drivers/tty/serial/msm_serial.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index 4b6c78331a64..cedcc36762a2 100644 --- 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); } |