[PATCH] block: don't error while flushing when write support is disabled

[Ahmad Fatoum]

On 1/15/26 3:24 PM, Enrico Jörns wrote:
> If write support for the underlying device is disabled (e.g. by
> disabling CONFIG_MCI_WRITE), blk->ops->write will be NULL.
> Unconditionally dereferencing/calling blk->ops->write() results in a
> NULL pointer dereference.
> 
> Fix this by making chunk_flush() a noop for missing write support.
> Don't return an error since there should be nothing to flush if write
> support is disabled, anyway.
> 
> Note that barebox currently does not prevent calling write/flush
> operations, even if CONFIG_MCI_WRITE and thus write support is actually
> disabled.
> But this should be handled on another level.
> 
> Signed-off-by: Enrico Jörns <ejo at pengutronix.de>

Reviewed-by: Ahmad Fatoum <a.fatoum at pengutronix.de>

Thanks,
Ahmad

> ---
>  common/block.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/common/block.c b/common/block.c
> index ca2ed37dbd..abd05eab39 100644
> --- a/common/block.c
> +++ b/common/block.c
> @@ -60,6 +60,9 @@ static int chunk_flush(struct block_device *blk, struct chunk *chunk)
>  	if (!chunk->dirty)
>  		return 0;
>  
> +	if (!blk->ops->write)
> +		return 0;
> +
>  	len = writebuffer_io_len(blk, chunk);
>  	ret = blk->ops->write(blk, chunk->data, chunk->block_start, len);
>  	if (ret < 0)

-- 
Pengutronix e.K.                  |                             |
Steuerwalder Str. 21              | http://www.pengutronix.de/  |
31137 Hildesheim, Germany         | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |