This is a note to let you know that I've just added the patch titled
serial: sirf: fix kernel panic caused by unpaired spinlock
to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-next branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will also be merged in the next major kernel release
during the merge window.
If you have any questions about this process, please let me know.
>From fb78b811422cd2d8c8605949cc4cc13618347ad5 Mon Sep 17 00:00:00 2001
From: Qipan Li <Qipan.Li@xxxxxxx>
Date: Mon, 27 Jan 2014 14:23:39 +0800
Subject: serial: sirf: fix kernel panic caused by unpaired spinlock
commit 8b9ade9f74f8a279 coming from Viresh Kumar "tty: serial: sirfsoc: drop
uart_port->lock before calling tty_flip_buffer_push()" broke sirfsoc uart
driver by knic:
[ 5.129122] BUG: spinlock already unlocked on CPU#0, ip6tables/1331
[ 5.132554] lock: sirfsoc_uart_ports+0x4/0x8a0, .magic: dead4ead,
.owner: <none>/-1, .owner_cpu: -1
[ 5.141651] CPU: 0 PID: 1331 Comm: ip6tables Tainted: G
W O 3.10.16 #3
[ 5.148866] [<c0013528>] (unwind_backtrace+0x0/0xe0) from
[<c0010e70>] (show_stack+0x10/0x14)
[ 5.157362] [<c0010e70>] (show_stack+0x10/0x14) from
[<c01a5e68>] (do_raw_spin_unlock+0x40/0xc8)
[ 5.166125] [<c01a5e68>] (do_raw_spin_unlock+0x40/0xc8) from
[<c03ff8b4>] (_raw_spin_unlock+0x8/0x40)
[ 5.175322] [<c03ff8b4>] (_raw_spin_unlock+0x8/0x40) from
[<c0203fcc>] (sirfsoc_uart_pio_rx_chars+0xa4/0xc0)
[ 5.185120] [<c0203fcc>]
(sirfsoc_uart_pio_rx_chars+0xa4/0xc0) from [<c0204fb8>]
(sirfsoc_rx_tmo_process_tl+0xdc/0x1e0)
[ 5.195875] [<c0204fb8>]
(sirfsoc_rx_tmo_process_tl+0xdc/0x1e0) from [<c0024b50>]
(tasklet_action+0x8c/0xec)
[ 5.205673] [<c0024b50>] (tasklet_action+0x8c/0xec) from
[<c00242a8>] (__do_softirq+0xec/0x1d4)
[ 5.214347] [<c00242a8>] (__do_softirq+0xec/0x1d4) from
[<c0024428>] (do_softirq+0x48/0x54)
[ 5.222674] [<c0024428>] (do_softirq+0x48/0x54) from
[<c0024690>] (irq_exit+0x74/0xc0)
[ 5.230573] [<c0024690>] (irq_exit+0x74/0xc0) from
[<c000e1e8>] (handle_IRQ+0x6c/0x90)
[ 5.238465] [<c000e1e8>] (handle_IRQ+0x6c/0x90) from
[<c000d500>] (__irq_svc+0x40/0x70)
[ 5.246446] [<c000d500>] (__irq_svc+0x40/0x70) from
[<c0092e7c>] (mark_page_accessed+0xc/0x68)
[ 5.255034] [<c0092e7c>] (mark_page_accessed+0xc/0x68) from
[<c00a2a4c>] (unmap_single_vma+0x3bc/0x550)
[ 5.264402] [<c00a2a4c>] (unmap_single_vma+0x3bc/0x550) from
[<c00a3b4c>] (unmap_vmas+0x44/0x54)
[ 5.273164] [<c00a3b4c>] (unmap_vmas+0x44/0x54) from
[<c00a81a8>] (exit_mmap+0xc4/0x1e0)
[ 5.281233] [<c00a81a8>] (exit_mmap+0xc4/0x1e0) from
[<c001bb78>] (mmput+0x3c/0xdc)
[ 5.288868] [<c001bb78>] (mmput+0x3c/0xdc) from [<c0021b0c>]
(do_exit+0x30c/0x828)
[ 5.296413] [<c0021b0c>] (do_exit+0x30c/0x828) from
[<c0022dac>] (do_group_exit+0x4c/0xb0)
[ 5.304653] [<c0022dac>] (do_group_exit+0x4c/0xb0) from
[<c0022e20>] (__wake_up_parent+0x0/0x18)
Root cause:
the commit dropped uart_port->lock before calling tty_flip_buffer_push(), but in sirfsoc-uart,
sirfsoc_uart_pio_rx_chars() can be called by sirfsoc_rx_tmo_process_tl(). here uart_port->lock
has not been taken yet. so that caused unpaired lock/unlock.
Solution:
This patch is doing a quick fix for that, it adds spin_lock/unlock(&port->lock) protect to
sirfsoc_uart_pio_rx_chars() in sirfsoc_rx_tmo_process_tl() to keep spin_lock/unlock in pair.
Signed-off-by: Qipan Li <Qipan.Li@xxxxxxx>
Signed-off-by: Barry Song <Baohua.Song@xxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx> # 3.12
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/sirfsoc_uart.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/sirfsoc_uart.c b/drivers/tty/serial/sirfsoc_uart.c
index 49a2ffd101a7..b7bfe24d4ebc 100644
--- a/drivers/tty/serial/sirfsoc_uart.c
+++ b/drivers/tty/serial/sirfsoc_uart.c
@@ -542,8 +542,10 @@ static void sirfsoc_rx_tmo_process_tl(unsigned long param)
wr_regl(port, ureg->sirfsoc_rx_dma_io_ctrl,
rd_regl(port, ureg->sirfsoc_rx_dma_io_ctrl) |
SIRFUART_IO_MODE);
- sirfsoc_uart_pio_rx_chars(port, 4 - sirfport->rx_io_count);
spin_unlock_irqrestore(&sirfport->rx_lock, flags);
+ spin_lock(&port->lock);
+ sirfsoc_uart_pio_rx_chars(port, 4 - sirfport->rx_io_count);
+ spin_unlock(&port->lock);
if (sirfport->rx_io_count == 4) {
spin_lock_irqsave(&sirfport->rx_lock, flags);
sirfport->rx_io_count = 0;
--
1.8.5.1.163.gd7aced9
--
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