tools/rtla: Fix uninitialized bucket/data->bucket_size warning

When compiling rtla with clang, I am getting the following warnings:

$ make HOSTCC=clang CC=clang LLVM_IAS=1

[..]
clang -O -g -DVERSION=\"6.8.0-rc3\" -flto=auto -fexceptions
	-fstack-protector-strong -fasynchronous-unwind-tables
	-fstack-clash-protection  -Wall -Werror=format-security
	-Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS
	$(pkg-config --cflags libtracefs)
	-c -o src/osnoise_hist.o src/osnoise_hist.c
src/osnoise_hist.c:138:6: warning: variable 'bucket' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
  138 |         if (data->bucket_size)
      |             ^~~~~~~~~~~~~~~~~
src/osnoise_hist.c:149:6: note: uninitialized use occurs here
  149 |         if (bucket < entries)
      |             ^~~~~~
src/osnoise_hist.c:138:2: note: remove the 'if' if its condition is always true
  138 |         if (data->bucket_size)
      |         ^~~~~~~~~~~~~~~~~~~~~~
  139 |                 bucket = duration / data->bucket_size;
src/osnoise_hist.c:132:12: note: initialize the variable 'bucket' to silence this warning
  132 |         int bucket;
      |                   ^
      |                    = 0
1 warning generated.

[...]

clang -O -g -DVERSION=\"6.8.0-rc3\" -flto=auto -fexceptions
	-fstack-protector-strong -fasynchronous-unwind-tables
	-fstack-clash-protection  -Wall -Werror=format-security
	-Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS
	$(pkg-config --cflags libtracefs)
	-c -o src/timerlat_hist.o src/timerlat_hist.c
src/timerlat_hist.c:181:6: warning: variable 'bucket' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
  181 |         if (data->bucket_size)
      |             ^~~~~~~~~~~~~~~~~
src/timerlat_hist.c:204:6: note: uninitialized use occurs here
  204 |         if (bucket < entries)
      |             ^~~~~~
src/timerlat_hist.c:181:2: note: remove the 'if' if its condition is always true
  181 |         if (data->bucket_size)
      |         ^~~~~~~~~~~~~~~~~~~~~~
  182 |                 bucket = latency / data->bucket_size;
src/timerlat_hist.c:175:12: note: initialize the variable 'bucket' to silence this warning
  175 |         int bucket;
      |                   ^
      |                    = 0
1 warning generated.

This is a legit warning, but data->bucket_size is always > 0 (see
timerlat_hist_parse_args()), so the if is not necessary.

Remove the unneeded if (data->bucket_size) to avoid the warning.

Link: https://lkml.kernel.org/r/6e1b1665cd99042ae705b3e0fc410858c4c42346.1707217097.git.bristot@kernel.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Bill Wendling <morbo@google.com>
Cc: Justin Stitt <justinstitt@google.com>
Cc: Donald Zickus <dzickus@redhat.com>
Fixes: 1eeb6328e8b3 ("rtla/timerlat: Add timerlat hist mode")
Fixes: 829a6c0b5698 ("rtla/osnoise: Add the hist mode")
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>

diff --git a/tools/tracing/rtla/src/osnoise_hist.c b/tools/tracing/rtla/src/osnoise_hist.c
index 8f81fa007364890dd4303b047c484786a56390f2..67128171c29d79f2b7fa8ea5bfbd4a2005cdf10e 100644 (file)
--- a/tools/tracing/rtla/src/osnoise_hist.c
+++ b/tools/tracing/rtla/src/osnoise_hist.c
@@ -135,8 +135,7 @@ static void osnoise_hist_update_multiple(struct osnoise_tool *tool, int cpu,
        if (params->output_divisor)
                duration = duration / params->output_divisor;
 
-       if (data->bucket_size)
-               bucket = duration / data->bucket_size;
+       bucket = duration / data->bucket_size;
 
        total_duration = duration * count;
 

diff --git a/tools/tracing/rtla/src/timerlat_hist.c b/tools/tracing/rtla/src/timerlat_hist.c
index 47d3d8b53cb2177fe7db4c39a21e630aca22fa23..3a5b8c409e7d8fa79ba149e93e15ea50c3941f79 100644 (file)
--- a/tools/tracing/rtla/src/timerlat_hist.c
+++ b/tools/tracing/rtla/src/timerlat_hist.c
@@ -178,8 +178,7 @@ timerlat_hist_update(struct osnoise_tool *tool, int cpu,
        if (params->output_divisor)
                latency = latency / params->output_divisor;
 
-       if (data->bucket_size)
-               bucket = latency / data->bucket_size;
+       bucket = latency / data->bucket_size;
 
        if (!context) {
                hist = data->hist[cpu].irq;