[alsa-devel] [PATCH] MPU401 lockups

[Takashi Iwai]

At Mon, 25 Jun 2007 13:44:49 +1100,
Serge Nikolaenko wrote:
> 
> [1  <text/plain; us-ascii (7bit)>]
> Hello,
> 
> The attachement is the fix for mpu to prevent lockups/freezes. Added mutexes 
> with down_trylock() calls, to prevent blocking.

Using mutex in the irq handler is scary (even though you're using
trylock).  What about simply using spin_lock_irqsave() instead of
spin_lock() in _snd_mpu401_uart_interrupt() (maybe in
uart_interrupt_tx(), too) ?


Takashi


> Midi in/out not tested - I don't have no midi devices at the moment.
> 
> My soundcard is ESI Juli at . MB integrated midi is disabled in bios.
> 
> Last system messages after system freeze when running wine/jackd:
> 
> kernel: cmd: 0xff failed at 0xac0c (status = 0xb, data = 0x0)
> ...
> kernel: BUG: soft lockup detected on CPU#0!
> kernel:
> kernel: Call Trace:
> kernel:  <IRQ>  [<ffffffff802b0bdb>] softlockup_tick+0xdb/0xf6
> kernel:  [<ffffffff8028f5d0>] update_process_times+0x42/0x68
> kernel:  [<ffffffff80271f0c>] smp_local_timer_interrupt+0x34/0x55
> kernel:  [<ffffffff802725e8>] smp_apic_timer_interrupt+0x51/0x69
> kernel:  [<ffffffff8025ace6>] apic_timer_interrupt+0x66/0x70
> kernel:  [<ffffffff889c600d>] :snd_mpu401_uart:mpu401_read_port+0x4/0x8
> kernel:  
> [<ffffffff889c62f0>] :snd_mpu401_uart:_snd_mpu401_uart_interrupt+0x4c/0x70
> kernel:  
> [<ffffffff889c6391>] :snd_mpu401_uart:snd_mpu401_uart_interrupt+0x13/0x1a
> kernel:  [<ffffffff88a1f34b>] :snd_ice1724:snd_vt1724_interrupt+0x4e/0x13a
> kernel:  [<ffffffff80210b93>] handle_IRQ_event+0x25/0x53
> kernel:  [<ffffffff802b202a>] handle_fasteoi_irq+0x92/0xd1
> kernel:  [<ffffffff8026862a>] do_IRQ+0xff/0x16d
> kernel:  [<ffffffff8025a631>] ret_from_intr+0x0/0xa
> kernel:  <EOI>  [<ffffffff802f5df7>] proc_info_read+0x0/0xb9
> kernel:  [<ffffffff802f5df9>] proc_info_read+0x2/0xb9
> kernel:  [<ffffffff8020b14e>] vfs_read+0xcb/0x173
> kernel:  [<ffffffff80211847>] sys_read+0x45/0x6e
> kernel:  [<ffffffff8025a11e>] system_call+0x7e/0x83	
> [2 mpu401_mutex.diff <text/x-diff; us-ascii (7bit)>]
> diff -urN a/sound/drivers/mpu401/mpu401_uart.c b/sound/drivers/mpu401/mpu401_uart.c
> --- a/sound/drivers/mpu401/mpu401_uart.c	2006-12-06 01:58:01.000000000 +1000
> +++ b/sound/drivers/mpu401/mpu401_uart.c	2007-06-22 18:21:57.000000000 +1100
> @@ -46,6 +46,9 @@
>  static void snd_mpu401_uart_input_read(struct snd_mpu401 * mpu);
>  static void snd_mpu401_uart_output_write(struct snd_mpu401 * mpu);
>  
> +DECLARE_MUTEX(mpu_tx_mutex);
> +DECLARE_MUTEX(mpu_interrupt_mutex);
> +
>  /*
>  
>   */
> @@ -103,6 +106,8 @@
>  		snd_mpu401_uart_output_write(mpu);
>  		spin_unlock(&mpu->output_lock);
>  	}
> +	
> +	up(&mpu_tx_mutex);
>  }
>  
>  static void _snd_mpu401_uart_interrupt(struct snd_mpu401 *mpu)
> @@ -116,9 +121,16 @@
>  		spin_unlock(&mpu->input_lock);
>  	}
>  	if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
> +	{
>  		/* ok. for better Tx performance try do some output
>  		   when input is done */
> +	    if (!down_trylock(&mpu_tx_mutex))
> +	    {
>  		uart_interrupt_tx(mpu);
> +	    }
> +	}
> +	
> +	up(&mpu_interrupt_mutex);
>  }
>  
>  /**
> @@ -134,7 +146,10 @@
>  	
>  	if (mpu == NULL)
>  		return IRQ_NONE;
> -	_snd_mpu401_uart_interrupt(mpu);
> +	if (!down_trylock(&mpu_interrupt_mutex))
> +	{
> +	    _snd_mpu401_uart_interrupt(mpu);
> +	}
>  	return IRQ_HANDLED;
>  }
>  
> @@ -153,7 +168,10 @@
>  	
>  	if (mpu == NULL)
>  		return IRQ_NONE;
> -	uart_interrupt_tx(mpu);
> +	if (!down_trylock(&mpu_tx_mutex))
> +	{
> +	    uart_interrupt_tx(mpu);
> +	}
>  	return IRQ_HANDLED;
>  }
>  
> [3  <text/plain; us-ascii (7bit)>]
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