From: Stephen Boyd <sboyd@codeaurora.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>,
linux-serial@vger.kernel.org, linux-arm-msm@vger.kernel.org,
linux-kernel@vger.kernel.org,
Frank Rowand <frank.rowand@sonymobile.com>,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] tty: serial: msm: Fix sysrq spinlock recursion on non-DM
Date: Wed, 29 Oct 2014 11:14:37 -0700 [thread overview]
Message-ID: <1414606478-13709-2-git-send-email-sboyd@codeaurora.org> (raw)
In-Reply-To: <1414606478-13709-1-git-send-email-sboyd@codeaurora.org>
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>
---
drivers/tty/serial/msm_serial.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
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);
}
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
WARNING: multiple messages have this Message-ID (diff)
From: sboyd@codeaurora.org (Stephen Boyd)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] tty: serial: msm: Fix sysrq spinlock recursion on non-DM
Date: Wed, 29 Oct 2014 11:14:37 -0700 [thread overview]
Message-ID: <1414606478-13709-2-git-send-email-sboyd@codeaurora.org> (raw)
In-Reply-To: <1414606478-13709-1-git-send-email-sboyd@codeaurora.org>
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>
---
drivers/tty/serial/msm_serial.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
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);
}
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
WARNING: multiple messages have this Message-ID (diff)
From: Stephen Boyd <sboyd@codeaurora.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-serial@vger.kernel.org,
Frank Rowand <frank.rowand@sonymobile.com>,
Daniel Thompson <daniel.thompson@linaro.org>
Subject: [PATCH 1/2] tty: serial: msm: Fix sysrq spinlock recursion on non-DM
Date: Wed, 29 Oct 2014 11:14:37 -0700 [thread overview]
Message-ID: <1414606478-13709-2-git-send-email-sboyd@codeaurora.org> (raw)
In-Reply-To: <1414606478-13709-1-git-send-email-sboyd@codeaurora.org>
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>
---
drivers/tty/serial/msm_serial.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
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);
}
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2014-10-29 18:14 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-29 18:14 [PATCH 0/2] Two msm_serial break fixes Stephen Boyd
2014-10-29 18:14 ` Stephen Boyd
2014-10-29 18:14 ` Stephen Boyd [this message]
2014-10-29 18:14 ` [PATCH 1/2] tty: serial: msm: Fix sysrq spinlock recursion on non-DM Stephen Boyd
2014-10-29 18:14 ` Stephen Boyd
2014-10-30 11:26 ` Daniel Thompson
2014-10-30 11:26 ` Daniel Thompson
2014-10-30 13:29 ` Peter Hurley
2014-10-30 13:29 ` Peter Hurley
2014-10-29 18:14 ` [PATCH 2/2] tty: serial: msm: Support sysrq on uartDM devices Stephen Boyd
2014-10-29 18:14 ` Stephen Boyd
2014-10-30 11:30 ` Daniel Thompson
2014-10-30 11:30 ` Daniel Thompson
2014-10-31 6:41 ` Stephen Boyd
2014-10-31 6:41 ` Stephen Boyd
2014-10-31 6:41 ` Stephen Boyd
2014-10-31 9:43 ` Daniel Thompson
2014-10-31 9:43 ` Daniel Thompson
2014-10-31 18:08 ` Frank Rowand
2014-10-31 18:08 ` Frank Rowand
2014-11-03 10:05 ` Daniel Thompson
2014-11-03 10:05 ` Daniel Thompson
2014-11-04 3:00 ` Frank Rowand
2014-11-04 3:00 ` Frank Rowand
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