[PATCH] mtd: fix cfi_cmdset_0001 FL_SYNCING race (take 2)

[Nicolas Pitre]

On Thu, 25 Sep 2008, Alexander Belyakov wrote:

> The patch fixes CFI issue with multipartitional devices leading to the set of errors or even deadlock. The problem is CFI FL_SYNCING state race with flash operations (e.g. erase suspend). It is reproduced by running intensive writes on one JFFS2 partition and simultaneously performing mount/unmount cycle on another partition of the same chip.
> 
> 
> ---
> Signed-off-by: Alexander Belyakov <abelyako at googlemail.com>

You should put your Signed-off-by line above the 3 dashes.  Everything 
below the 3 dashes is ignored for the commit log.

Acked-by: Nicolas Pitre <nico at cam.org> otherwise.


> 
> diff -uNrp a/drivers/mtd/chips/cfi_cmdset_0001.c b/drivers/mtd/chips/cfi_cmdset_0001.c
> --- a/drivers/mtd/chips/cfi_cmdset_0001.c	2008-09-08 21:40:20.000000000 +0400
> +++ b/drivers/mtd/chips/cfi_cmdset_0001.c	2008-09-19 10:47:34.000000000 +0400
> @@ -701,6 +701,10 @@ static int chip_ready (struct map_info *
>  	struct cfi_pri_intelext *cfip = cfi->cmdset_priv;
>  	unsigned long timeo = jiffies + HZ;
>  
> +	/* Prevent setting state FL_SYNCING for chip in suspended state. */
> +	if (mode == FL_SYNCING && chip->oldstate != FL_READY)
> +		goto sleep;
> +
>  	switch (chip->state) {
>  
>  	case FL_STATUS:
> @@ -806,8 +810,9 @@ static int get_chip(struct map_info *map
>  	DECLARE_WAITQUEUE(wait, current);
>  
>   retry:
> -	if (chip->priv && (mode == FL_WRITING || mode == FL_ERASING
> -			   || mode == FL_OTP_WRITE || mode == FL_SHUTDOWN)) {
> +	if (chip->priv &&
> +	    (mode == FL_WRITING || mode == FL_ERASING || mode == FL_OTP_WRITE
> +	    || mode == FL_SHUTDOWN) && chip->state != FL_SYNCING) {
>  		/*
>  		 * OK. We have possibility for contention on the write/erase
>  		 * operations which are global to the real chip and not per
> @@ -857,6 +862,14 @@ static int get_chip(struct map_info *map
>  				return ret;
>  			}
>  			spin_lock(&shared->lock);
> +
> +			/* We should not own chip if it is already
> +			 * in FL_SYNCING state. Put contender and retry. */
> +			if (chip->state == FL_SYNCING) {
> +				put_chip(map, contender, contender->start);
> +				spin_unlock(contender->mutex);
> +				goto retry;
> +			}
>  			spin_unlock(contender->mutex);
>  		}
>  
> 


Nicolas