[PATCH] xenbaked.c: Avoid divide by zero issue on dump_stats()

[PATCH] xenbaked.c: Avoid divide by zero issue on dump_stats()

[Joe Jin]

run_time on dump_stats() maybe zero if break xenmon.py immediately after it
started, then xenbaked hit divide by zero fault.

Signed-off-by: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
---
 tools/xenmon/xenbaked.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/tools/xenmon/xenbaked.c b/tools/xenmon/xenbaked.c
index 3d9e0ed900..d3f940a26b 100644
--- a/tools/xenmon/xenbaked.c
+++ b/tools/xenmon/xenbaked.c
@@ -243,10 +243,12 @@ static void dump_stats(void)
     }
 
     printf("processed %d total records in %d seconds (%ld per second)\n",
-           rec_count, (int)run_time, (long)(rec_count/run_time));
+           rec_count, (int)run_time,
+           run_time ? (long)(rec_count/run_time) : 0L);
 
-    printf("woke up %d times in %d seconds (%ld per second)\n", wakeups,
-	   (int) run_time, (long)(wakeups/run_time));
+    printf("woke up %d times in %d seconds (%ld per second)\n",
+           wakeups, (int) run_time,
+           run_time ? (long)(wakeups/run_time) : 0L);
 
     check_gotten_sum();
 }
-- 
2.14.3 (Apple Git-98)


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Re: [PATCH] xenbaked.c: Avoid divide by zero issue on dump_stats()

[Konrad Rzeszutek Wilk]

On Tue, Mar 13, 2018 at 06:38:24PM -0700, Joe Jin wrote:
> run_time on dump_stats() maybe zero if break xenmon.py immediately after it

s/maybe/can be/
> started, then xenbaked hit divide by zero fault.

And:

"Note that run_time is computed using two values which are retrieved using 'time'
system call which gives us resolution in seconds."

> 
> Signed-off-by: Joe Jin <joe.jin@oracle.com>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: Wei Liu <wei.liu2@citrix.com>
> Cc: Ian Campbell <ian.campbell@citrix.com>
> ---
>  tools/xenmon/xenbaked.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/xenmon/xenbaked.c b/tools/xenmon/xenbaked.c
> index 3d9e0ed900..d3f940a26b 100644
> --- a/tools/xenmon/xenbaked.c
> +++ b/tools/xenmon/xenbaked.c
> @@ -243,10 +243,12 @@ static void dump_stats(void)
>      }
>  
>      printf("processed %d total records in %d seconds (%ld per second)\n",
> -           rec_count, (int)run_time, (long)(rec_count/run_time));
> +           rec_count, (int)run_time,
> +           run_time ? (long)(rec_count/run_time) : 0L);
>  
> -    printf("woke up %d times in %d seconds (%ld per second)\n", wakeups,
> -	   (int) run_time, (long)(wakeups/run_time));
> +    printf("woke up %d times in %d seconds (%ld per second)\n",
> +           wakeups, (int) run_time,
> +           run_time ? (long)(wakeups/run_time) : 0L);
>  
>      check_gotten_sum();
>  }
> -- 
> 2.14.3 (Apple Git-98)
> 

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Re: [PATCH] xenbaked.c: Avoid divide by zero issue on dump_stats()

[George Dunlap]

On Wed, Mar 14, 2018 at 2:24 AM, Konrad Rzeszutek Wilk
<konrad.wilk@oracle.com> wrote:
> On Tue, Mar 13, 2018 at 06:38:24PM -0700, Joe Jin wrote:
>> run_time on dump_stats() maybe zero if break xenmon.py immediately after it
>
> s/maybe/can be/
>> started, then xenbaked hit divide by zero fault.
>
> And:
>
> "Note that run_time is computed using two values which are retrieved using 'time'
> system call which gives us resolution in seconds."

Is anyone still using this?  Does it even work?  I thought we had
talked about removing it at some point.

 -George

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Re: [PATCH] xenbaked.c: Avoid divide by zero issue on dump_stats()

[Konrad Rzeszutek Wilk]

On Wed, Mar 14, 2018 at 10:54:42AM +0000, George Dunlap wrote:
> On Wed, Mar 14, 2018 at 2:24 AM, Konrad Rzeszutek Wilk
> <konrad.wilk@oracle.com> wrote:
> > On Tue, Mar 13, 2018 at 06:38:24PM -0700, Joe Jin wrote:
> >> run_time on dump_stats() maybe zero if break xenmon.py immediately after it
> >
> > s/maybe/can be/
> >> started, then xenbaked hit divide by zero fault.
> >
> > And:
> >
> > "Note that run_time is computed using two values which are retrieved using 'time'
> > system call which gives us resolution in seconds."
> 
> Is anyone still using this?  Does it even work?  I thought we had

Yes as we found out as folks start coming out of the woods with the need
to update their OS thanks to spectre.

They use it with 'xenmon.py' combination.

> talked about removing it at some point.
> 
>  -George

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