On 06/05/12 16:13, Christoph Bartoschek wrote:
> I get the following race from DRD:
>
> Conflicting store by thread 7 at 0x55fe8aa0 size 8
> by 0x5CCD8750: func() (inv_utils.C:1711)
> by 0x4C2C0C1: ??? (in /usr/lib64/valgrind/vgpreload_drd-amd64-linux.so)
> by 0x5047F04: start_thread (in /lib64/libpthread-2.14.1.so)
> by 0x5CB710C: clone (in /lib64/libc-2.14.1.so)
> Address 0x55fe8aa0 is at offset 0 from 0x55fe8aa0. Allocation context:
> at 0x4C2BC9D: malloc (in
> /usr/lib64/valgrind/vgpreload_drd-amd64-linux.so)
> by 0x5CCD849F: func() (inv_utils.C:1690)
> by 0x4C2C0C1: ??? (in /usr/lib64/valgrind/vgpreload_drd-amd64-linux.so)
> by 0x5047F04: start_thread (in /lib64/libpthread-2.14.1.so)
> by 0x5CB710C: clone (in /lib64/libc-2.14.1.so)
> Other segment start (thread 6)
> at 0x4C31712: pthread_spin_lock (in
> /usr/lib64/valgrind/vgpreload_drd-amd64-linux.so)
> by 0x22C031FD: hunc (bn_thread.C:43)
> by 0x4C2C0C1: ??? (in /usr/lib64/valgrind/vgpreload_drd-amd64-linux.so)
> by 0x5047F04: start_thread (in /lib64/libpthread-2.14.1.so)
> by 0x5CB710C: clone (in /lib64/libc-2.14.1.so)
> Other segment end (thread 6)
> at 0x4C30EC2: pthread_spin_init (in
> /usr/lib64/valgrind/vgpreload_drd-amd64-linux.so)
> by 0x22C032AD: hunc (bn_thread.C:47)
> by 0x4C2C0C1: ??? (in /usr/lib64/valgrind/vgpreload_drd-amd64-linux.so)
> by 0x5047F04: start_thread (in /lib64/libpthread-2.14.1.so)
> by 0x5CB710C: clone (in /lib64/libc-2.14.1.so)
>
>
>
> The function func() is in essence:
>
> {
> int * data = malloc(100);
> for (int i = 0; i != 100; ++i) {
> data[i] = 0; <------- Line 1711
> }
>
> // Some small calculations
>
> free(data);
> }
>
>
> So I wonder how there can be a data race for writting to data. The
> memory has been just allocated and no other thread knows about it.
>
> How can this happen?
Was that output produced by Valgrind 3.7.0 ? If so, do you get the same
output if you build Valgrind from the SVN trunk ?
Bart.
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