When building with -Wsometimes-uninitialized, Clang warns:
net/wireless/util.c:1223:11: warning: variable 'result' is used
uninitialized whenever 'if' condition is false
[-Wsometimes-uninitialized]
Clang can't evaluate at this point that WARN(1, ...) always returns true
because __ret_warn_on is defined as !!(condition), which isn't
immediately evaluated as 1. Change this branch to else so that it's
clear to Clang that we intend to bail out here.
Link: https://github.com/ClangBuiltLinux/linux/issues/382
Suggested-by: Nick Desaulniers <[email protected]>
Signed-off-by: Nathan Chancellor <[email protected]>
---
net/wireless/util.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/net/wireless/util.c b/net/wireless/util.c
index e4b8db5e81ec..75899b62bdc9 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1220,9 +1220,11 @@ static u32 cfg80211_calculate_bitrate_he(struct rate_info *rate)
else if (rate->bw == RATE_INFO_BW_HE_RU &&
rate->he_ru_alloc == NL80211_RATE_INFO_HE_RU_ALLOC_26)
result = rates_26[rate->he_gi];
- else if (WARN(1, "invalid HE MCS: bw:%d, ru:%d\n",
- rate->bw, rate->he_ru_alloc))
+ else {
+ WARN(1, "invalid HE MCS: bw:%d, ru:%d\n",
+ rate->bw, rate->he_ru_alloc);
return 0;
+ }
/* now scale to the appropriate MCS */
tmp = result;
--
2.21.0
On Thu, Mar 7, 2019 at 3:57 PM Nathan Chancellor
<[email protected]> wrote:
>
> When building with -Wsometimes-uninitialized, Clang warns:
>
> net/wireless/util.c:1223:11: warning: variable 'result' is used
> uninitialized whenever 'if' condition is false
> [-Wsometimes-uninitialized]
>
> Clang can't evaluate at this point that WARN(1, ...) always returns true
> because __ret_warn_on is defined as !!(condition), which isn't
> immediately evaluated as 1. Change this branch to else so that it's
> clear to Clang that we intend to bail out here.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/382
> Suggested-by: Nick Desaulniers <[email protected]>
> Signed-off-by: Nathan Chancellor <[email protected]>
Thanks for the quick fix!
Reviewed-by: Nick Desaulniers <[email protected]>
> ---
> net/wireless/util.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/net/wireless/util.c b/net/wireless/util.c
> index e4b8db5e81ec..75899b62bdc9 100644
> --- a/net/wireless/util.c
> +++ b/net/wireless/util.c
> @@ -1220,9 +1220,11 @@ static u32 cfg80211_calculate_bitrate_he(struct rate_info *rate)
> else if (rate->bw == RATE_INFO_BW_HE_RU &&
> rate->he_ru_alloc == NL80211_RATE_INFO_HE_RU_ALLOC_26)
> result = rates_26[rate->he_gi];
> - else if (WARN(1, "invalid HE MCS: bw:%d, ru:%d\n",
> - rate->bw, rate->he_ru_alloc))
> + else {
> + WARN(1, "invalid HE MCS: bw:%d, ru:%d\n",
> + rate->bw, rate->he_ru_alloc);
> return 0;
> + }
>
> /* now scale to the appropriate MCS */
> tmp = result;
> --
> 2.21.0
>
--
Thanks,
~Nick Desaulniers
On Thu, Mar 07, 2019 at 04:57:35PM -0700, Nathan Chancellor wrote:
> When building with -Wsometimes-uninitialized, Clang warns:
>
> net/wireless/util.c:1223:11: warning: variable 'result' is used
> uninitialized whenever 'if' condition is false
> [-Wsometimes-uninitialized]
>
> Clang can't evaluate at this point that WARN(1, ...) always returns true
> because __ret_warn_on is defined as !!(condition), which isn't
> immediately evaluated as 1. Change this branch to else so that it's
> clear to Clang that we intend to bail out here.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/382
> Suggested-by: Nick Desaulniers <[email protected]>
> Signed-off-by: Nathan Chancellor <[email protected]>
> ---
> net/wireless/util.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/net/wireless/util.c b/net/wireless/util.c
> index e4b8db5e81ec..75899b62bdc9 100644
> --- a/net/wireless/util.c
> +++ b/net/wireless/util.c
> @@ -1220,9 +1220,11 @@ static u32 cfg80211_calculate_bitrate_he(struct rate_info *rate)
> else if (rate->bw == RATE_INFO_BW_HE_RU &&
> rate->he_ru_alloc == NL80211_RATE_INFO_HE_RU_ALLOC_26)
> result = rates_26[rate->he_gi];
> - else if (WARN(1, "invalid HE MCS: bw:%d, ru:%d\n",
> - rate->bw, rate->he_ru_alloc))
> + else {
> + WARN(1, "invalid HE MCS: bw:%d, ru:%d\n",
> + rate->bw, rate->he_ru_alloc);
> return 0;
> + }
>
> /* now scale to the appropriate MCS */
> tmp = result;
> --
> 2.21.0
>
Gentle ping (if there was a response to this, I didn't receive it). I
know I sent it in the middle of a merge window so I get if it slipped
through the cracks.
Thanks,
Nathan
On Fri, Mar 8, 2019 at 12:57 AM Nathan Chancellor
<[email protected]> wrote:
>
> When building with -Wsometimes-uninitialized, Clang warns:
>
> net/wireless/util.c:1223:11: warning: variable 'result' is used
> uninitialized whenever 'if' condition is false
> [-Wsometimes-uninitialized]
>
> Clang can't evaluate at this point that WARN(1, ...) always returns true
> because __ret_warn_on is defined as !!(condition), which isn't
> immediately evaluated as 1. Change this branch to else so that it's
> clear to Clang that we intend to bail out here.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/382
> Suggested-by: Nick Desaulniers <[email protected]>
> Signed-off-by: Nathan Chancellor <[email protected]>
> ---
> net/wireless/util.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/net/wireless/util.c b/net/wireless/util.c
> index e4b8db5e81ec..75899b62bdc9 100644
> --- a/net/wireless/util.c
> +++ b/net/wireless/util.c
> @@ -1220,9 +1220,11 @@ static u32 cfg80211_calculate_bitrate_he(struct rate_info *rate)
> else if (rate->bw == RATE_INFO_BW_HE_RU &&
> rate->he_ru_alloc == NL80211_RATE_INFO_HE_RU_ALLOC_26)
> result = rates_26[rate->he_gi];
> - else if (WARN(1, "invalid HE MCS: bw:%d, ru:%d\n",
> - rate->bw, rate->he_ru_alloc))
> + else {
> + WARN(1, "invalid HE MCS: bw:%d, ru:%d\n",
> + rate->bw, rate->he_ru_alloc);
> return 0;
> + }
Reviewed-by: Arnd Bergmann <[email protected]>
I independently came up with the same fix before I saw yours,
the only difference was that I avoided the extra curly braces
using
+ else
+ return !WARN(1, "invalid HE MCS: bw:%d, ru:%d\n",
+ rate->bw, rate->he_ru_alloc);
to avoid the mix of bare if() and if() {}
Arnd
On Fri, Mar 22, 2019 at 03:16:06PM +0100, Arnd Bergmann wrote:
> On Fri, Mar 8, 2019 at 12:57 AM Nathan Chancellor
> <[email protected]> wrote:
> >
> > When building with -Wsometimes-uninitialized, Clang warns:
> >
> > net/wireless/util.c:1223:11: warning: variable 'result' is used
> > uninitialized whenever 'if' condition is false
> > [-Wsometimes-uninitialized]
> >
> > Clang can't evaluate at this point that WARN(1, ...) always returns true
> > because __ret_warn_on is defined as !!(condition), which isn't
> > immediately evaluated as 1. Change this branch to else so that it's
> > clear to Clang that we intend to bail out here.
> >
> > Link: https://github.com/ClangBuiltLinux/linux/issues/382
> > Suggested-by: Nick Desaulniers <[email protected]>
> > Signed-off-by: Nathan Chancellor <[email protected]>
> > ---
> > net/wireless/util.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/net/wireless/util.c b/net/wireless/util.c
> > index e4b8db5e81ec..75899b62bdc9 100644
> > --- a/net/wireless/util.c
> > +++ b/net/wireless/util.c
> > @@ -1220,9 +1220,11 @@ static u32 cfg80211_calculate_bitrate_he(struct rate_info *rate)
> > else if (rate->bw == RATE_INFO_BW_HE_RU &&
> > rate->he_ru_alloc == NL80211_RATE_INFO_HE_RU_ALLOC_26)
> > result = rates_26[rate->he_gi];
> > - else if (WARN(1, "invalid HE MCS: bw:%d, ru:%d\n",
> > - rate->bw, rate->he_ru_alloc))
> > + else {
> > + WARN(1, "invalid HE MCS: bw:%d, ru:%d\n",
> > + rate->bw, rate->he_ru_alloc);
> > return 0;
> > + }
>
> Reviewed-by: Arnd Bergmann <[email protected]>
>
> I independently came up with the same fix before I saw yours,
> the only difference was that I avoided the extra curly braces
> using
>
> + else
> + return !WARN(1, "invalid HE MCS: bw:%d, ru:%d\n",
> + rate->bw, rate->he_ru_alloc);
>
> to avoid the mix of bare if() and if() {}
Right, shouldn't all arms of the if/else if/else conditional have {}
if any arm has {}.