[dpdk-dev] [PATCH] pci: remove unnecessary access() check

[dpdk-dev] [PATCH] pci: remove unnecessary access() check

[Stephen Hemminger]

Just open the sysfs file and handle failure, rather than
using access(). This eliminates Coverity warnings about
"time of check versus time of use"; although for this sysfs
file that is not really an issue anyway.

Coverity ID: 347276
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 drivers/bus/pci/linux/pci.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
index 43debaa25114..6c444aa7ae3d 100644
--- a/drivers/bus/pci/linux/pci.c
+++ b/drivers/bus/pci/linux/pci.c
@@ -512,18 +512,19 @@ pci_device_iommu_support_va(const struct rte_pci_device *dev)
 		 "%s/" PCI_PRI_FMT "/iommu/intel-iommu/cap",
 		 rte_pci_get_sysfs_path(), addr->domain, addr->bus, addr->devid,
 		 addr->function);
-	if (access(filename, F_OK) == -1) {
-		/* We don't have an Intel IOMMU, assume VA supported*/
-		return true;
-	}
 
-	/* We have an intel IOMMU */
 	fp = fopen(filename, "r");
 	if (fp == NULL) {
-		RTE_LOG(ERR, EAL, "%s(): can't open %s\n", __func__, filename);
+		/* We don't have an Intel IOMMU, assume VA supported*/
+		if (errno == ENOENT)
+			return true;
+
+		RTE_LOG(ERR, EAL, "%s(): can't open %s: %s\n",
+			__func__, filename, strerror(errno));
 		return false;
 	}
 
+	/* We have an intel IOMMU */
 	if (fscanf(fp, "%" PRIx64, &vtd_cap_reg) != 1) {
 		RTE_LOG(ERR, EAL, "%s(): can't read %s\n", __func__, filename);
 		fclose(fp);
-- 
2.20.1

Re: [dpdk-dev] [PATCH] pci: remove unnecessary access() check

[David Marchand]

On Tue, Aug 13, 2019 at 5:38 PM Stephen Hemminger
<stephen@networkplumber.org> wrote:
>
> Just open the sysfs file and handle failure, rather than
> using access(). This eliminates Coverity warnings about
> "time of check versus time of use"; although for this sysfs
> file that is not really an issue anyway.
>
> Coverity ID: 347276
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

Title prefix should be "bus/pci: " (check-git-log.sh).


> ---
>  drivers/bus/pci/linux/pci.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
> index 43debaa25114..6c444aa7ae3d 100644
> --- a/drivers/bus/pci/linux/pci.c
> +++ b/drivers/bus/pci/linux/pci.c
> @@ -512,18 +512,19 @@ pci_device_iommu_support_va(const struct rte_pci_device *dev)
>                  "%s/" PCI_PRI_FMT "/iommu/intel-iommu/cap",
>                  rte_pci_get_sysfs_path(), addr->domain, addr->bus, addr->devid,
>                  addr->function);
> -       if (access(filename, F_OK) == -1) {
> -               /* We don't have an Intel IOMMU, assume VA supported*/
> -               return true;
> -       }
>
> -       /* We have an intel IOMMU */
>         fp = fopen(filename, "r");
>         if (fp == NULL) {
> -               RTE_LOG(ERR, EAL, "%s(): can't open %s\n", __func__, filename);
> +               /* We don't have an Intel IOMMU, assume VA supported*/

Nit: missing a space before closing the comment.

> +               if (errno == ENOENT)
> +                       return true;
> +
> +               RTE_LOG(ERR, EAL, "%s(): can't open %s: %s\n",
> +                       __func__, filename, strerror(errno));
>                 return false;
>         }
>
> +       /* We have an intel IOMMU */
>         if (fscanf(fp, "%" PRIx64, &vtd_cap_reg) != 1) {
>                 RTE_LOG(ERR, EAL, "%s(): can't read %s\n", __func__, filename);
>                 fclose(fp);
> --
> 2.20.1
>

Reviewed-by: David Marchand <david.marchand@redhat.com>


-- 
David Marchand

Re: [dpdk-dev] [PATCH] pci: remove unnecessary access() check

[David Marchand]

On Mon, Aug 19, 2019 at 11:58 AM David Marchand
<david.marchand@redhat.com> wrote:
>
> On Tue, Aug 13, 2019 at 5:38 PM Stephen Hemminger
> <stephen@networkplumber.org> wrote:
> >
> > Just open the sysfs file and handle failure, rather than
> > using access(). This eliminates Coverity warnings about
> > "time of check versus time of use"; although for this sysfs
> > file that is not really an issue anyway.
> >
> > Coverity ID: 347276

Fixed Coverity tag.
Added Fixes: + Cc: stable@dpdk.org

> > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
>
> Title prefix should be "bus/pci: " (check-git-log.sh).

Updated commit title.

>
>
> > ---
> >  drivers/bus/pci/linux/pci.c | 13 +++++++------
> >  1 file changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
> > index 43debaa25114..6c444aa7ae3d 100644
> > --- a/drivers/bus/pci/linux/pci.c
> > +++ b/drivers/bus/pci/linux/pci.c
> > @@ -512,18 +512,19 @@ pci_device_iommu_support_va(const struct rte_pci_device *dev)
> >                  "%s/" PCI_PRI_FMT "/iommu/intel-iommu/cap",
> >                  rte_pci_get_sysfs_path(), addr->domain, addr->bus, addr->devid,
> >                  addr->function);
> > -       if (access(filename, F_OK) == -1) {
> > -               /* We don't have an Intel IOMMU, assume VA supported*/
> > -               return true;
> > -       }
> >
> > -       /* We have an intel IOMMU */
> >         fp = fopen(filename, "r");
> >         if (fp == NULL) {
> > -               RTE_LOG(ERR, EAL, "%s(): can't open %s\n", __func__, filename);
> > +               /* We don't have an Intel IOMMU, assume VA supported*/
>
> Nit: missing a space before closing the comment.
>
> > +               if (errno == ENOENT)
> > +                       return true;
> > +
> > +               RTE_LOG(ERR, EAL, "%s(): can't open %s: %s\n",
> > +                       __func__, filename, strerror(errno));
> >                 return false;
> >         }
> >
> > +       /* We have an intel IOMMU */

s/intel/Intel/

> >         if (fscanf(fp, "%" PRIx64, &vtd_cap_reg) != 1) {
> >                 RTE_LOG(ERR, EAL, "%s(): can't read %s\n", __func__, filename);
> >                 fclose(fp);
> > --
> > 2.20.1
> >
>
> Reviewed-by: David Marchand <david.marchand@redhat.com>

Applied, thanks!



--
David Marchand