[PATCH][next] PCI: Fix ternary operator that never returns 0

[PATCH][next] PCI: Fix ternary operator that never returns 0

[Colin Ian King]

The left hand size of the ? operator is always true because of the addition
of PCIE_STD_NUM_TLP_HEADERLOG and so dev->eetlp_prefix_max is always being
returned and the 0 is never returned (dead code). Fix this by adding the
required parentheses around the ternary operator.

Fixes: 00048c2d5f11 ("PCI: Add TLP Prefix reading to pcie_read_tlp_log()")
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
---
 drivers/pci/pcie/tlp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pcie/tlp.c b/drivers/pci/pcie/tlp.c
index 9b9e348fb1a0..0860b5da837f 100644
--- a/drivers/pci/pcie/tlp.c
+++ b/drivers/pci/pcie/tlp.c
@@ -22,8 +22,8 @@
 unsigned int aer_tlp_log_len(struct pci_dev *dev, u32 aercc)
 {
 	return PCIE_STD_NUM_TLP_HEADERLOG +
-	       (aercc & PCI_ERR_CAP_PREFIX_LOG_PRESENT) ?
-	       dev->eetlp_prefix_max : 0;
+	       ((aercc & PCI_ERR_CAP_PREFIX_LOG_PRESENT) ?
+		dev->eetlp_prefix_max : 0);
 }
 
 #ifdef CONFIG_PCIE_DPC
-- 
2.47.1

Re: [PATCH][next] PCI: Fix ternary operator that never returns 0

[Bjorn Helgaas]

On Thu, Jan 16, 2025 at 05:20:19PM +0000, Colin Ian King wrote:
> The left hand size of the ? operator is always true because of the addition
> of PCIE_STD_NUM_TLP_HEADERLOG and so dev->eetlp_prefix_max is always being
> returned and the 0 is never returned (dead code). Fix this by adding the
> required parentheses around the ternary operator.
> 
> Fixes: 00048c2d5f11 ("PCI: Add TLP Prefix reading to pcie_read_tlp_log()")
> Signed-off-by: Colin Ian King <colin.i.king@gmail.com>

Squashed into the 00048c2d5f11 ("PCI: Add TLP Prefix reading to
pcie_read_tlp_log()") commit, headed for v6.14, thanks!

> ---
>  drivers/pci/pcie/tlp.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/pcie/tlp.c b/drivers/pci/pcie/tlp.c
> index 9b9e348fb1a0..0860b5da837f 100644
> --- a/drivers/pci/pcie/tlp.c
> +++ b/drivers/pci/pcie/tlp.c
> @@ -22,8 +22,8 @@
>  unsigned int aer_tlp_log_len(struct pci_dev *dev, u32 aercc)
>  {
>  	return PCIE_STD_NUM_TLP_HEADERLOG +
> -	       (aercc & PCI_ERR_CAP_PREFIX_LOG_PRESENT) ?
> -	       dev->eetlp_prefix_max : 0;
> +	       ((aercc & PCI_ERR_CAP_PREFIX_LOG_PRESENT) ?
> +		dev->eetlp_prefix_max : 0);
>  }
>  
>  #ifdef CONFIG_PCIE_DPC
> -- 
> 2.47.1
> 

Re: [PATCH][next] PCI: Fix ternary operator that never returns 0

[David Laight]

On Thu, 16 Jan 2025 17:20:19 +0000
Colin Ian King <colin.i.king@gmail.com> wrote:

> The left hand size of the ? operator is always true because of the addition
> of PCIE_STD_NUM_TLP_HEADERLOG and so dev->eetlp_prefix_max is always being
> returned and the 0 is never returned (dead code). Fix this by adding the
> required parentheses around the ternary operator.
> 
> Fixes: 00048c2d5f11 ("PCI: Add TLP Prefix reading to pcie_read_tlp_log()")
> Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
> ---
>  drivers/pci/pcie/tlp.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/pcie/tlp.c b/drivers/pci/pcie/tlp.c
> index 9b9e348fb1a0..0860b5da837f 100644
> --- a/drivers/pci/pcie/tlp.c
> +++ b/drivers/pci/pcie/tlp.c
> @@ -22,8 +22,8 @@
>  unsigned int aer_tlp_log_len(struct pci_dev *dev, u32 aercc)
>  {
>  	return PCIE_STD_NUM_TLP_HEADERLOG +
> -	       (aercc & PCI_ERR_CAP_PREFIX_LOG_PRESENT) ?
> -	       dev->eetlp_prefix_max : 0;
> +	       ((aercc & PCI_ERR_CAP_PREFIX_LOG_PRESENT) ?

You can remove the extra set around the condition itself as well.
They are a good hint the writer doesn't know their operator
precedences :-)

	David

> +		dev->eetlp_prefix_max : 0);
>  }
>  
>  #ifdef CONFIG_PCIE_DPC

Re: [PATCH][next] PCI: Fix ternary operator that never returns 0

[Dan Carpenter]

On Thu, Jan 16, 2025 at 10:49:44PM +0000, David Laight wrote:
> On Thu, 16 Jan 2025 17:20:19 +0000
> Colin Ian King <colin.i.king@gmail.com> wrote:
> 
> > The left hand size of the ? operator is always true because of the addition
> > of PCIE_STD_NUM_TLP_HEADERLOG and so dev->eetlp_prefix_max is always being
> > returned and the 0 is never returned (dead code). Fix this by adding the
> > required parentheses around the ternary operator.
> > 
> > Fixes: 00048c2d5f11 ("PCI: Add TLP Prefix reading to pcie_read_tlp_log()")
> > Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
> > ---
> >  drivers/pci/pcie/tlp.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/pci/pcie/tlp.c b/drivers/pci/pcie/tlp.c
> > index 9b9e348fb1a0..0860b5da837f 100644
> > --- a/drivers/pci/pcie/tlp.c
> > +++ b/drivers/pci/pcie/tlp.c
> > @@ -22,8 +22,8 @@
> >  unsigned int aer_tlp_log_len(struct pci_dev *dev, u32 aercc)
> >  {
> >  	return PCIE_STD_NUM_TLP_HEADERLOG +
> > -	       (aercc & PCI_ERR_CAP_PREFIX_LOG_PRESENT) ?
> > -	       dev->eetlp_prefix_max : 0;
> > +	       ((aercc & PCI_ERR_CAP_PREFIX_LOG_PRESENT) ?
> 
> You can remove the extra set around the condition itself as well.
> They are a good hint the writer doesn't know their operator
> precedences :-)

Please leave them as-is...  I obsolutely do not remember the operator
precedences between & and ? and I have to look it up every time I see
it.

regards,
dan carpenter