[PATCH 0/5] Use IS_ERR() rather than a NULL check when necessary.

[PATCH 0/5] Use IS_ERR() rather than a NULL check when necessary.

[Cyril Roelandt]

The following five patches replace NULL checks by calls to IS_ERR() when
checking the return values of functions that return ERR_PTR() on error.

Regards,
Cyril Roelandt.
---

Cyril Roelandt (5):
  staging: omap-thermal: fix error check in
    omap_thermal_expose_sensor() and in
    omap_thermal_register_cpu_cooling().
  media: davinci: fix return value check in vpbe_display_reqbufs().
  c2port: fix return value check in duramar2150_c2port_init().
  net: sfc: fix return value check in efx_ptp_probe_channel().
  spi: fix return value check in hspi_probe().

 drivers/media/platform/davinci/vpbe_display.c      |    2 +-
 drivers/misc/c2port/c2port-duramar2150.c           |    2 +-
 drivers/net/ethernet/sfc/ptp.c                     |    2 +-
 drivers/spi/spi-sh-hspi.c                          |    2 +-
 drivers/staging/omap-thermal/omap-thermal-common.c |    4 ++--
 5 files changed, 6 insertions(+), 6 deletions(-)

-- 
1.7.10.4

[PATCH 1/5] staging: omap-thermal: fix error check in omap_thermal_expose_sensor() and in omap_therm

[Cyril Roelandt]

The omap_bandgap_get_sensor_data() function returns ERR_PTR(), so we need to use
IS_ERR() rather than a NULL check.

Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
---
 drivers/staging/omap-thermal/omap-thermal-common.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/omap-thermal/omap-thermal-common.c b/drivers/staging/omap-thermal/omap-thermal-common.c
index 61f1070..79a55aa 100644
--- a/drivers/staging/omap-thermal/omap-thermal-common.c
+++ b/drivers/staging/omap-thermal/omap-thermal-common.c
@@ -260,7 +260,7 @@ int omap_thermal_expose_sensor(struct omap_bandgap *bg_ptr, int id,
 
 	data = omap_bandgap_get_sensor_data(bg_ptr, id);
 
-	if (!data)
+	if (IS_ERR(data))
 		data = omap_thermal_build_data(bg_ptr, id);
 
 	if (!data)
@@ -309,7 +309,7 @@ int omap_thermal_register_cpu_cooling(struct omap_bandgap *bg_ptr, int id)
 	struct omap_thermal_data *data;
 
 	data = omap_bandgap_get_sensor_data(bg_ptr, id);
-	if (!data)
+	if (IS_ERR(data))
 		data = omap_thermal_build_data(bg_ptr, id);
 
 	if (!data)
-- 
1.7.10.4

Re: [PATCH 1/5] staging: omap-thermal: fix error check in omap_thermal_expose_sensor() and in omap_t

[Eduardo Valentin]

On 12-12-2012 02:24, Cyril Roelandt wrote:
>
> The omap_bandgap_get_sensor_data() function returns ERR_PTR(), so we need to use
> IS_ERR() rather than a NULL check.
>
> Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>

Acked-by: Eduardo Valentin <eduardo.valentin@ti.com>

> ---
>   drivers/staging/omap-thermal/omap-thermal-common.c |    4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/omap-thermal/omap-thermal-common.c b/drivers/staging/omap-thermal/omap-thermal-common.c
> index 61f1070..79a55aa 100644
> --- a/drivers/staging/omap-thermal/omap-thermal-common.c
> +++ b/drivers/staging/omap-thermal/omap-thermal-common.c
> @@ -260,7 +260,7 @@ int omap_thermal_expose_sensor(struct omap_bandgap *bg_ptr, int id,
>
>   	data = omap_bandgap_get_sensor_data(bg_ptr, id);
>
> -	if (!data)
> +	if (IS_ERR(data))
>   		data = omap_thermal_build_data(bg_ptr, id);
>
>   	if (!data)
> @@ -309,7 +309,7 @@ int omap_thermal_register_cpu_cooling(struct omap_bandgap *bg_ptr, int id)
>   	struct omap_thermal_data *data;
>
>   	data = omap_bandgap_get_sensor_data(bg_ptr, id);
> -	if (!data)
> +	if (IS_ERR(data))
>   		data = omap_thermal_build_data(bg_ptr, id);
>
>   	if (!data)
>

[PATCH 2/5] media: davinci: fix return value check in vpbe_display_reqbufs().

[Cyril Roelandt]

vb2_dma_contig_init_ctx() returns ERR_PTR and never returns NULL, so IS_ERR
should be used instead of a NULL check.

Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
---
 drivers/media/platform/davinci/vpbe_display.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/platform/davinci/vpbe_display.c b/drivers/media/platform/davinci/vpbe_display.c
index 2bfde79..2db4eff 100644
--- a/drivers/media/platform/davinci/vpbe_display.c
+++ b/drivers/media/platform/davinci/vpbe_display.c
@@ -1393,7 +1393,7 @@ static int vpbe_display_reqbufs(struct file *file, void *priv,
 	}
 	/* Initialize videobuf queue as per the buffer type */
 	layer->alloc_ctx = vb2_dma_contig_init_ctx(vpbe_dev->pdev);
-	if (!layer->alloc_ctx) {
+	if (IS_ERR(layer->alloc_ctx)) {
 		v4l2_err(&vpbe_dev->v4l2_dev, "Failed to get the context\n");
 		return -EINVAL;
 	}
-- 
1.7.10.4

Re: [PATCH 2/5] media: davinci: fix return value check in vpbe_display_reqbufs().

[Prabhakar Lad]

Hi Cyril,

On Wed, Dec 12, 2012 at 5:54 AM, Cyril Roelandt <tipecaml@gmail.com> wrote:
> vb2_dma_contig_init_ctx() returns ERR_PTR and never returns NULL, so IS_ERR
> should be used instead of a NULL check.
>
patch fixing this issue has been already posted with a better fix
https://patchwork.kernel.org/patch/1830231/

Regards,
--Prabhakar Lad

> Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
> ---
>  drivers/media/platform/davinci/vpbe_display.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/davinci/vpbe_display.c b/drivers/media/platform/davinci/vpbe_display.c
> index 2bfde79..2db4eff 100644
> --- a/drivers/media/platform/davinci/vpbe_display.c
> +++ b/drivers/media/platform/davinci/vpbe_display.c
> @@ -1393,7 +1393,7 @@ static int vpbe_display_reqbufs(struct file *file, void *priv,
>         }
>         /* Initialize videobuf queue as per the buffer type */
>         layer->alloc_ctx = vb2_dma_contig_init_ctx(vpbe_dev->pdev);
> -       if (!layer->alloc_ctx) {
> +       if (IS_ERR(layer->alloc_ctx)) {
>                 v4l2_err(&vpbe_dev->v4l2_dev, "Failed to get the context\n");
>                 return -EINVAL;
>         }
> --
> 1.7.10.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-media" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH 3/5] c2port: fix return value check in duramar2150_c2port_init().

[Cyril Roelandt]

The c2port_device_register() function returns ERR_PTR() and never returns NULL,
so the NULL check should be replaced by a call to IS_ERR().

Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
---
 drivers/misc/c2port/c2port-duramar2150.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/c2port/c2port-duramar2150.c b/drivers/misc/c2port/c2port-duramar2150.c
index 5484301..2742e60 100644
--- a/drivers/misc/c2port/c2port-duramar2150.c
+++ b/drivers/misc/c2port/c2port-duramar2150.c
@@ -129,7 +129,7 @@ static int __init duramar2150_c2port_init(void)
 
 	duramar2150_c2port_dev = c2port_device_register("uc",
 					&duramar2150_c2port_ops, NULL);
-	if (!duramar2150_c2port_dev) {
+	if (IS_ERR(duramar2150_c2port_dev)) {
 		ret = -ENODEV;
 		goto free_region;
 	}
-- 
1.7.10.4

[PATCH 4/5] net: sfc: fix return value check in efx_ptp_probe_channel().

[Cyril Roelandt]

The ptp_clock_register() returns ERR_PTR() and never returns NULL. Replace the
NULL check by a call to IS_ERR().

Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
---
 drivers/net/ethernet/sfc/ptp.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/sfc/ptp.c b/drivers/net/ethernet/sfc/ptp.c
index 0767043f..9bcc38c 100644
--- a/drivers/net/ethernet/sfc/ptp.c
+++ b/drivers/net/ethernet/sfc/ptp.c
@@ -930,7 +930,7 @@ static int efx_ptp_probe_channel(struct efx_channel *channel)
 
 	ptp->phc_clock = ptp_clock_register(&ptp->phc_clock_info,
 					    &efx->pci_dev->dev);
-	if (!ptp->phc_clock)
+	if (IS_ERR(ptp->phc_clock))
 		goto fail3;
 
 	INIT_WORK(&ptp->pps_work, efx_ptp_pps_worker);
-- 
1.7.10.4

Re: [PATCH 4/5] net: sfc: fix return value check in efx_ptp_probe_channel().

[David Miller]

From: Cyril Roelandt <tipecaml@gmail.com>
Date: Wed, 12 Dec 2012 01:24:53 +0100

> The ptp_clock_register() returns ERR_PTR() and never returns NULL. Replace the
> NULL check by a call to IS_ERR().
> 
> Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>

I'll let Ben queue this up.

Probably he'll want to avoid potentially leaving an ERR_PTR
in ptp->phc_clock even if, with this fix, that would be
harmless.

Re: [PATCH 4/5] net: sfc: fix return value check in efx_ptp_probe_channel().

[Ben Hutchings]

On Wed, 2012-12-12 at 00:15 -0500, David Miller wrote:
> From: Cyril Roelandt <tipecaml@gmail.com>
> Date: Wed, 12 Dec 2012 01:24:53 +0100
> 
> > The ptp_clock_register() returns ERR_PTR() and never returns NULL. Replace the
> > NULL check by a call to IS_ERR().
> > 
> > Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
> 
> I'll let Ben queue this up.
> 
> Probably he'll want to avoid potentially leaving an ERR_PTR
> in ptp->phc_clock even if, with this fix, that would be
> harmless.

Sorry for the delay in looking at this.  This change is fine, as the
entire structure *ptp will be freed on the failure path.

I'm now on vacation until the new year.  Cyril, please re-send your
patch with the addition of:

Acked-by: Ben Hutchings <bhutchings@solarflare.com>

so it will show up on 'patchwork' again and David can apply it from
there.

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

[PATCH 5/5] spi: fix return value check in hspi_probe().

[Cyril Roelandt]

According to its documentation, clk_get() returns a "valid IS_ERR() condition
containing errno", so we should call IS_ERR() rather than a NULL check.

Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
---
 drivers/spi/spi-sh-hspi.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/spi-sh-hspi.c b/drivers/spi/spi-sh-hspi.c
index 32f7b55..60cfae5 100644
--- a/drivers/spi/spi-sh-hspi.c
+++ b/drivers/spi/spi-sh-hspi.c
@@ -290,7 +290,7 @@ static int hspi_probe(struct platform_device *pdev)
 	}
 
 	clk = clk_get(NULL, "shyway_clk");
-	if (!clk) {
+	if (IS_ERR(clk)) {
 		dev_err(&pdev->dev, "shyway_clk is required\n");
 		ret = -EINVAL;
 		goto error0;
-- 
1.7.10.4

Re: [PATCH 5/5] spi: fix return value check in hspi_probe().

[Kuninori Morimoto]

Hi

> According to its documentation, clk_get() returns a "valid IS_ERR() condition
> containing errno", so we should call IS_ERR() rather than a NULL check.
> 
> Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>

Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>

> ---
>  drivers/spi/spi-sh-hspi.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/spi/spi-sh-hspi.c b/drivers/spi/spi-sh-hspi.c
> index 32f7b55..60cfae5 100644
> --- a/drivers/spi/spi-sh-hspi.c
> +++ b/drivers/spi/spi-sh-hspi.c
> @@ -290,7 +290,7 @@ static int hspi_probe(struct platform_device *pdev)
>  	}
>  
>  	clk = clk_get(NULL, "shyway_clk");
> -	if (!clk) {
> +	if (IS_ERR(clk)) {
>  		dev_err(&pdev->dev, "shyway_clk is required\n");
>  		ret = -EINVAL;
>  		goto error0;
> -- 
> 1.7.10.4
> 
> 
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Best regards
---
Kuninori Morimoto

Re: [PATCH 5/5] spi: fix return value check in hspi_probe().

[Grant Likely]

On Tue, 11 Dec 2012 16:36:27 -0800 (PST), Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> wrote:
> 
> Hi
> 
> > According to its documentation, clk_get() returns a "valid IS_ERR() condition
> > containing errno", so we should call IS_ERR() rather than a NULL check.
> > 
> > Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
> 
> Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>

Applied, thanks.

g.

Re: [PATCH 5/5] spi: fix return value check in hspi_probe().

[Dan Carpenter]

On Wed, Dec 19, 2012 at 03:11:54PM +0000, Grant Likely wrote:
> On Tue, 11 Dec 2012 16:36:27 -0800 (PST), Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> wrote:
> > 
> > Hi
> > 
> > > According to its documentation, clk_get() returns a "valid IS_ERR() condition
> > > containing errno", so we should call IS_ERR() rather than a NULL check.
> > > 
> > > Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
> > 
> > Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
> 
> Applied, thanks.

In another thread, we were just talking about who clk_get() can
return a NULL if !CONFIG_HAVE_CLK.  That might change to match the
documentation later...  Not sure.

regards,
dan carpenter

Re: [PATCH 5/5] spi: fix return value check in hspi_probe().

[Grant Likely]

On Wed, 19 Dec 2012 19:39:14 +0300, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> On Wed, Dec 19, 2012 at 03:11:54PM +0000, Grant Likely wrote:
> > On Tue, 11 Dec 2012 16:36:27 -0800 (PST), Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> wrote:
> > > 
> > > Hi
> > > 
> > > > According to its documentation, clk_get() returns a "valid IS_ERR() condition
> > > > containing errno", so we should call IS_ERR() rather than a NULL check.
> > > > 
> > > > Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
> > > 
> > > Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
> > 
> > Applied, thanks.
> 
> In another thread, we were just talking about who clk_get() can
> return a NULL if !CONFIG_HAVE_CLK.  That might change to match the
> documentation later...  Not sure.

So what is the solution here? Will the dummy clk_get() be changed, or is
there more work needed on the drivers?

/me stifles a rant about the PTR_ERR pattern

g.

Re: [PATCH 5/5] spi: fix return value check in hspi_probe().

[Dan Carpenter]

On Sat, Dec 22, 2012 at 09:56:20AM +0000, Grant Likely wrote:
> On Wed, 19 Dec 2012 19:39:14 +0300, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > On Wed, Dec 19, 2012 at 03:11:54PM +0000, Grant Likely wrote:
> > > On Tue, 11 Dec 2012 16:36:27 -0800 (PST), Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> wrote:
> > > > 
> > > > Hi
> > > > 
> > > > > According to its documentation, clk_get() returns a "valid IS_ERR() condition
> > > > > containing errno", so we should call IS_ERR() rather than a NULL check.
> > > > > 
> > > > > Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
> > > > 
> > > > Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
> > > 
> > > Applied, thanks.
> > 
> > In another thread, we were just talking about who clk_get() can
> > return a NULL if !CONFIG_HAVE_CLK.  That might change to match the
> > documentation later...  Not sure.
> 
> So what is the solution here? Will the dummy clk_get() be changed, or is
> there more work needed on the drivers?
> 

This driver can't function without a clk.  It should select that at
build time instead of testing for it at probe.  Just checking for
IS_ERR() will NOT cause a NULL dereference so the patch is ok in
that respect.  I'm not sure if this can be build without
CONFIG_HAVE_CLK.

regards,
dan carpenter

Re: [PATCH 5/5] spi: fix return value check in hspi_probe().

[Grant Likely]

On Thu, 3 Jan 2013 19:04:55 +0300, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> On Sat, Dec 22, 2012 at 09:56:20AM +0000, Grant Likely wrote:
> > On Wed, 19 Dec 2012 19:39:14 +0300, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > > On Wed, Dec 19, 2012 at 03:11:54PM +0000, Grant Likely wrote:
> > > > On Tue, 11 Dec 2012 16:36:27 -0800 (PST), Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> wrote:
> > > > > 
> > > > > Hi
> > > > > 
> > > > > > According to its documentation, clk_get() returns a "valid IS_ERR() condition
> > > > > > containing errno", so we should call IS_ERR() rather than a NULL check.
> > > > > > 
> > > > > > Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
> > > > > 
> > > > > Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
> > > > 
> > > > Applied, thanks.
> > > 
> > > In another thread, we were just talking about who clk_get() can
> > > return a NULL if !CONFIG_HAVE_CLK.  That might change to match the
> > > documentation later...  Not sure.
> > 
> > So what is the solution here? Will the dummy clk_get() be changed, or is
> > there more work needed on the drivers?
> > 
> 
> This driver can't function without a clk.  It should select that at
> build time instead of testing for it at probe.  Just checking for
> IS_ERR() will NOT cause a NULL dereference so the patch is ok in
> that respect.  I'm not sure if this can be build without
> CONFIG_HAVE_CLK.

Your suggestion is to make this driver depend on CONFIG_HAVE_CLK? I'm
fine with that, but it doesn't sort out the core infrastructure question
about whether it is valid for the empty clk_get() to return NULL. Nor is
it a particularly sustainable solution (ie. if a large number of drivers
want to do the same thing).

g.

Re: [PATCH 5/5] spi: fix return value check in hspi_probe().

[Dan Carpenter]

On Fri, Jan 11, 2013 at 03:02:02PM +0000, Grant Likely wrote:
> On Thu, 3 Jan 2013 19:04:55 +0300, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > On Sat, Dec 22, 2012 at 09:56:20AM +0000, Grant Likely wrote:
> > > On Wed, 19 Dec 2012 19:39:14 +0300, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > > > On Wed, Dec 19, 2012 at 03:11:54PM +0000, Grant Likely wrote:
> > > > > On Tue, 11 Dec 2012 16:36:27 -0800 (PST), Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> wrote:
> > > > > > 
> > > > > > Hi
> > > > > > 
> > > > > > > According to its documentation, clk_get() returns a "valid IS_ERR() condition
> > > > > > > containing errno", so we should call IS_ERR() rather than a NULL check.
> > > > > > > 
> > > > > > > Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
> > > > > > 
> > > > > > Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
> > > > > 
> > > > > Applied, thanks.
> > > > 
> > > > In another thread, we were just talking about who clk_get() can
> > > > return a NULL if !CONFIG_HAVE_CLK.  That might change to match the
> > > > documentation later...  Not sure.
> > > 
> > > So what is the solution here? Will the dummy clk_get() be changed, or is
> > > there more work needed on the drivers?
> > > 
> > 
> > This driver can't function without a clk.  It should select that at
> > build time instead of testing for it at probe.  Just checking for
> > IS_ERR() will NOT cause a NULL dereference so the patch is ok in
> > that respect.  I'm not sure if this can be build without
> > CONFIG_HAVE_CLK.
> 
> Your suggestion is to make this driver depend on CONFIG_HAVE_CLK? I'm
> fine with that, but it doesn't sort out the core infrastructure question
> about whether it is valid for the empty clk_get() to return NULL. Nor is
> it a particularly sustainable solution (ie. if a large number of drivers
> want to do the same thing).
> 

We've spread this conversation out across several different threads.

http://lists.infradead.org/pipermail/linux-arm-kernel/2013-January/139186.html

Basically, drivers should use accessor functions which handle NULL
pointers instead of dereferencing the pointer directly.

regards,
dan carpenter