2005-11-11 03:09:16

by Florin Malita

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Subject: [PATCH] sa1100 serial: sa1100_start_tx spinlock recursion

The serial core aquires the port spinlock before calling
port->ops->start_tx(), so sa1100_start_tx() shouldn't try to lock it
again.

BUG: spinlock recursion on CPU#0, init/1
lock: c0205f20, .magic: dead4ead, .owner: init/1, .owner_cpu: 0
[<c0022cdc>] (dump_stack+0x0/0x14) [<c00dc338>] (spin_bug+0x0/0xbc)
[<c00dc6b0>] (_raw_spin_lock+0x0/0x170) r8 = 00000007 r7 = C02FE0070
[<c018a2a8>] (_spin_lock_irqsave+0x0/0x24) r4 = C0205F20
[<c0112110>] (sa1100_start_tx+0x0/0x40) r4 = C038C000
[<c010ee38>] (__uart_start+0x0/0x5c) [<c010ee94>] (uart_start+0x0/0x3
[<c010f1d0>] (uart_write+0x0/0xdc) [<c00fee34>] (write_chan+0x0/0x370



Signed-off-by: Florin Malita <[email protected]>
----
diff --git a/drivers/serial/sa1100.c b/drivers/serial/sa1100.c
--- a/drivers/serial/sa1100.c
+++ b/drivers/serial/sa1100.c
@@ -156,7 +156,7 @@ static void sa1100_stop_tx(struct uart_p
}

/*
- * interrupts may not be disabled on entry
+ * port locked and interrupts disabled
*/
static void sa1100_start_tx(struct uart_port *port)
{
@@ -164,11 +164,9 @@ static void sa1100_start_tx(struct uart_
unsigned long flags;
u32 utcr3;

- spin_lock_irqsave(&sport->port.lock, flags);
utcr3 = UART_GET_UTCR3(sport);
sport->port.read_status_mask |= UTSR0_TO_SM(UTSR0_TFS);
UART_PUT_UTCR3(sport, utcr3 | UTCR3_TIE);
- spin_unlock_irqrestore(&sport->port.lock, flags);
}

/*


2005-11-12 22:10:37

by Russell King

[permalink] [raw]
Subject: Re: [PATCH] sa1100 serial: sa1100_start_tx spinlock recursion

On Thu, Nov 10, 2005 at 10:09:37PM -0500, Florin Malita wrote:
> The serial core aquires the port spinlock before calling
> port->ops->start_tx(), so sa1100_start_tx() shouldn't try to lock it
> again.

Applied, thanks.

PS, please do not copy linux-kernel and linux-arm-kernel. The latter
is set for member only posting and it's considered rude to cross post.
Thanks.

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 Serial core