Re: [FYI PATCH] t/helper/test-lazy-name-hash: fix compilation

[Jeff Hostetler]

On 12/18/2017 4:49 PM, Stefan Beller wrote:

I was compiling origin/master today with stricter compiler flags today
and was greeted by

t/helper/test-lazy-init-name-hash.c: In function ‘cmd_main’:
t/helper/test-lazy-init-name-hash.c:172:5: error: ‘nr_threads_used’ may be used 
uninitialized in this function [-Werror=maybe-uninitialized]
  printf("avg [size %8d] [single %f] %c [multi %f %d]\n",
  ^~~
  nr,
  ~~~
  (double)avg_single/10,
  ~~
  (avg_single < avg_multi ? '<' : '>'),
  ~
  (double)avg_multi/10,
  ~
  nr_threads_used);
  
t/helper/test-lazy-init-name-hash.c:115:6: note: ‘nr_threads_used’ was declared 
here
   int nr_threads_used;
   ^~~

I do not see how we can arrive at that line without having `nr_threads_used`
initialized, as we'd have `count > 1`  (which asserts that we ran the
loop above at least once, such that it *should* be initialized).

I do not have time to dive into further analysis.

Signed-off-by: Stefan Beller 
---
  t/helper/test-lazy-init-name-hash.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/t/helper/test-lazy-init-name-hash.c 
b/t/helper/test-lazy-init-name-hash.c
index 6368a89345..297fb01d61 100644
--- a/t/helper/test-lazy-init-name-hash.c
+++ b/t/helper/test-lazy-init-name-hash.c
@@ -112,7 +112,7 @@ static void analyze_run(void)
  {
uint64_t t1s, t1m, t2s, t2m;
int cache_nr_limit;
-   int nr_threads_used;
+   int nr_threads_used = 0;
int i;
int nr;


Agreed. It should not be a problem.  Explicitly initializing it is fine.


Signed-off-by: Jeff Hostetler 

Re: [FYI PATCH] t/helper/test-lazy-name-hash: fix compilation

[Jonathan Tan]

On Mon, 18 Dec 2017 13:49:47 -0800
Stefan Beller  wrote:

> I was compiling origin/master today with stricter compiler flags today
> and was greeted by
> 
> t/helper/test-lazy-init-name-hash.c: In function ‘cmd_main’:
> t/helper/test-lazy-init-name-hash.c:172:5: error: ‘nr_threads_used’ may be 
> used uninitialized in this function [-Werror=maybe-uninitialized]
>  printf("avg [size %8d] [single %f] %c [multi %f %d]\n",
>  ^~~
>  nr,
>  ~~~
>  (double)avg_single/10,
>  ~~
>  (avg_single < avg_multi ? '<' : '>'),
>  ~
>  (double)avg_multi/10,
>  ~
>  nr_threads_used);
>  
> t/helper/test-lazy-init-name-hash.c:115:6: note: ‘nr_threads_used’ was 
> declared here
>   int nr_threads_used;
>   ^~~
> 
> I do not see how we can arrive at that line without having `nr_threads_used`
> initialized, as we'd have `count > 1`  (which asserts that we ran the
> loop above at least once, such that it *should* be initialized).

Your analysis makes sense. (The compiler probably couldn't detect it because
"count" is a static variable, not a local variable.)

> --- a/t/helper/test-lazy-init-name-hash.c
> +++ b/t/helper/test-lazy-init-name-hash.c
> @@ -112,7 +112,7 @@ static void analyze_run(void)
>  {
>   uint64_t t1s, t1m, t2s, t2m;
>   int cache_nr_limit;
> - int nr_threads_used;
> + int nr_threads_used = 0;
>   int i;
>   int nr;

I agree that this is probably the best way to fix it. Another way might
be to omit printing out the number of threads used in the printf that
prints the average statistics.

The best way is probably to not use so many global variables, but that
is out of scope of this change.

RE: FYI

[Denton, Cari-Lee]

From: Denton, Cari-Lee
Sent: July 6, 2014 12:44 AM
To: Denton, Cari-Lee
Subject: FYI

You are picked, e-mail: 
mackenzie.glo...@yahoo.esmailto:mackenzie.glo...@yahoo.es for Info.
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