Re: [LTP] [PATCH] ltp: Fix races in mmap1

[Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>]

On 08/28/2013 05:07 PM, Dave Kleikamp wrote:
> Make map_address a volatile pointer so that it is dereferenced in
> read_mem() after read_lock is set.
>
> Also read_lock must protect the verbose printf that reads from map_address
> as well.
>
> Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
>
> diff --git a/testcases/kernel/mem/mtest06/mmap1.c b/testcases/kernel/mem/mtest06/mmap1.c
> index 7c80bb4..cd1127f 100644
> --- a/testcases/kernel/mem/mtest06/mmap1.c
> +++ b/testcases/kernel/mem/mtest06/mmap1.c
> @@ -62,7 +62,7 @@
>   } while (0)
>   
>   static int verbose_print = 0;
> -static char *map_address;
> +static char *volatile map_address;
>   static jmp_buf jmpbuf;
>   static volatile char read_lock = 0;
>   
> @@ -228,11 +228,13 @@ void *read_mem(void *ptr)
>   				tst_resm(TINFO, "page fault occurred due to "
>   					 "a read after an unmap");
>   		} else {
> -			if (verbose_print)
> +			if (verbose_print) {
> +				read_lock = 1;
>   				tst_resm(TINFO,
>   					 "read_mem(): content of memory: %s",
>   					 (char *)map_address);
> -
> +				read_lock = 0;
> +			}
>   			for (j = 0; j < args[1]; j++) {
>   				read_lock = 1;
>   				if (map_address[j] != 'a')
>
> ------------------------------------------------------------------------------
> Learn the latest--Visual Studio 2012, SharePoint 2013, SQL 2012, more!
> Discover the easy way to master current and previous Microsoft technologies
> and advance your career. Get an incredible 1,500+ hours of step-by-step
> tutorial videos with LearnDevNow. Subscribe today and save!
> http://pubads.g.doubleclick.net/gampad/clk?id=58040911&iu=/4140/ostg.clktrk
> _______________________________________________
> Ltp-list mailing list
> Ltp-list@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/ltp-list

Just in case.. To reproduce failures we need to invoke the test this 
way, for example:

   ./mmap1 -v -s 10

and then wait few minutes (it depends...)


------------------------------------------------------------------------------
Learn the latest--Visual Studio 2012, SharePoint 2013, SQL 2012, more!
Discover the easy way to master current and previous Microsoft technologies
and advance your career. Get an incredible 1,500+ hours of step-by-step
tutorial videos with LearnDevNow. Subscribe today and save!
http://pubads.g.doubleclick.net/gampad/clk?id=58040911&iu=/4140/ostg.clktrk
_______________________________________________
Ltp-list mailing list
Ltp-list@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/ltp-list