linux-kernel - Re: [PATCH] mtd: spi-nor: cadence-quadspi: make return type fit wait_for_completion

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Date:   Fri, 27 Jul 2018 05:21:49 +0000
From:   Nicholas Mc Guire <der.herr@...r.at>
To:     Boris Brezillon <boris.brezillon@...tlin.com>
Cc:     Nicholas Mc Guire <hofrat@...dl.org>,
        Graham Moore <grmoore@...nsource.altera.com>,
        Vignesh R <vigneshr@...com>,
        Richard Weinberger <richard@....at>,
        linux-kernel@...r.kernel.org, Marek Vasut <marek.vasut@...il.com>,
        linux-mtd@...ts.infradead.org,
        Brian Norris <computersforpeace@...il.com>,
        David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH] mtd: spi-nor: cadence-quadspi: make return type fit
 wait_for_completion_timeout

On Thu, Jul 26, 2018 at 10:09:28PM +0200, Boris Brezillon wrote:
> On Wed, 25 Jul 2018 06:31:37 +0000
> Nicholas Mc Guire <der.herr@...r.at> wrote:
> 
> > On Tue, Jul 24, 2018 at 10:46:26PM +0200, Boris Brezillon wrote:
> > > On Sat, 21 Jul 2018 18:08:13 +0200
> > > Nicholas Mc Guire <hofrat@...dl.org> wrote:
> > >   
> > > > wait_for_completion_timeout returns an unsigned long not int. declare a
> > > > suitably type timeout and fix up assignment and check.
> > > > 
> > > > Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> > > > Reported-by: Vignesh R <vigneshr@...com>
> > > > Fixes: 140623410536 ("mtd: spi-nor: Add driver for Cadence Quad SPI Flash Controller")  
> > > 
> > > If you don't mind, I'd like to squash all wait_for_completion_timeout()
> > > fixes into a single commit.
> > >  
> > makes sense - no objections to that at all.
> 
> 
> I also dropped the timeout vars and checked the return of
> wait_for_completion_timeout() directly + removed the Fixes tag since
> it's no longer possible to attach the fix to a single commit and also,
> I'm sure the bug really existed (no overflow possible since the timeout
> values are small enough to fit in a signed int).
> 
> Here is the resulting patch. Let me know if you're okay with this version.
>

looks good to me - quit a bit simpler than what I did - thanks !

thx!
hofrat
 
> Thanks,
> 
> Boris
> 
> --->8---
> From 69edac4ef4d1c8dac519b6d12afd4097ce72a54e Mon Sep 17 00:00:00 2001
> From: Nicholas Mc Guire <hofrat@...dl.org>
> Date: Sat, 21 Jul 2018 16:21:51 +0200
> Subject: [PATCH] mtd: spi-nor: cadence-quadspi: fix timeout handling
> 
> wait_for_completion_timeout returns an unsigned long not an int, so
> let's check its return value directly instead of storing it in ret,
> and avoid checking for negative values since this cannot happen.
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> Signed-off-by: Boris Brezillon <boris.brezillon@...tlin.com>
> ---
>  drivers/mtd/spi-nor/cadence-quadspi.c | 20 ++++++++------------
>  1 file changed, 8 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c
> index c3f7aaa5d18f..7a19dae717fa 100644
> --- a/drivers/mtd/spi-nor/cadence-quadspi.c
> +++ b/drivers/mtd/spi-nor/cadence-quadspi.c
> @@ -525,15 +525,14 @@ static int cqspi_indirect_read_execute(struct spi_nor *nor, u8 *rxbuf,
>  	       reg_base + CQSPI_REG_INDIRECTRD);
>  
>  	while (remaining > 0) {
> -		ret = wait_for_completion_timeout(&cqspi->transfer_complete,
> -						  msecs_to_jiffies
> -						  (CQSPI_READ_TIMEOUT_MS));
> +		if (!wait_for_completion_timeout(&cqspi->transfer_complete,
> +				msecs_to_jiffies(CQSPI_READ_TIMEOUT_MS)))
> +			ret = -ETIMEDOUT;
>  
>  		bytes_to_read = cqspi_get_rd_sram_level(cqspi);
>  
> -		if (!ret && bytes_to_read == 0) {
> +		if (ret && bytes_to_read == 0) {
>  			dev_err(nor->dev, "Indirect read timeout, no bytes\n");
> -			ret = -ETIMEDOUT;
>  			goto failrd;
>  		}
>  
> @@ -649,10 +648,8 @@ static int cqspi_indirect_write_execute(struct spi_nor *nor, loff_t to_addr,
>  		iowrite32_rep(cqspi->ahb_base, txbuf,
>  			      DIV_ROUND_UP(write_bytes, 4));
>  
> -		ret = wait_for_completion_timeout(&cqspi->transfer_complete,
> -						  msecs_to_jiffies
> -						  (CQSPI_TIMEOUT_MS));
> -		if (!ret) {
> +		if (!wait_for_completion_timeout(&cqspi->transfer_complete,
> +					msecs_to_jiffies(CQSPI_TIMEOUT_MS))) {
>  			dev_err(nor->dev, "Indirect write timeout\n");
>  			ret = -ETIMEDOUT;
>  			goto failwr;
> @@ -986,9 +983,8 @@ static int cqspi_direct_read_execute(struct spi_nor *nor, u_char *buf,
>  	}
>  
>  	dma_async_issue_pending(cqspi->rx_chan);
> -	ret = wait_for_completion_timeout(&cqspi->rx_dma_complete,
> -					  msecs_to_jiffies(len));
> -	if (ret <= 0) {
> +	if (!wait_for_completion_timeout(&cqspi->rx_dma_complete,
> +					 msecs_to_jiffies(len))) {
>  		dmaengine_terminate_sync(cqspi->rx_chan);
>  		dev_err(nor->dev, "DMA wait_for_completion_timeout\n");
>  		ret = -ETIMEDOUT;