| Message ID | 20190307235735.31487-1-natechancellor@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Johannes Berg |
| Headers | show |
| Series | cfg80211: Change an 'else if' into an 'else' in cfg80211_calculate_bitrate_he | expand |
On Thu, Mar 7, 2019 at 3:57 PM Nathan Chancellor <natechancellor@gmail.com> 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 <ndesaulniers@google.com> > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Thanks for the quick fix! Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > --- > 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 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 <ndesaulniers@google.com> > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > --- > 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 <natechancellor@gmail.com> 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 <ndesaulniers@google.com> > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > --- > 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 <arnd@arndb.de> 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 > <natechancellor@gmail.com> 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 <ndesaulniers@google.com> > > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > > --- > > 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 <arnd@arndb.de> > > 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 {}.
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;
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 <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> --- net/wireless/util.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)