Re: [Qemu-devel] [PATCH] cpus: fix TCG timer leak

[Alex Bennée]

Marc-André Lureau <address@hidden> writes:

> Spotted by ASAN:
>
> QTEST_QEMU_BINARY=x86_64-softmmu/qemu-system-x86_64 tests/bios-tables-test  
> -p /x86_64/acpi/piix4/cpuhp
> /x86_64/acpi/piix4/cpuhp: Could not access KVM kernel module: No such file or 
> directory
> qemu-system-x86_64: failed to initialize KVM: No such file or directory
> qemu-system-x86_64: Back to tcg accelerator
> ==21216==WARNING: ASan doesn't fully support makecontext/swapcontext 
> functions and may produce false positives in some cases!
>
> =================================================================
> ==21216==ERROR: LeakSanitizer: detected memory leaks
>
> Direct leak of 48 byte(s) in 1 object(s) allocated from:
>     #0 0x7f77c0668e50 in calloc (/lib64/libasan.so.5+0xeee50)
>     #1 0x7f77beb7b41d in g_malloc0 (/lib64/libglib-2.0.so.0+0x5241d)
>     #2 0x557f756df5bd in timer_new 
> /home/elmarco/src/qemu/include/qemu/timer.h:561
>     #3 0x557f756df5ee in timer_new_ns 
> /home/elmarco/src/qemu/include/qemu/timer.h:584
>     #4 0x557f756e4690 in start_tcg_kick_timer 
> /home/elmarco/src/qemu/cpus.c:965
>     #5 0x557f756e64d7 in qemu_tcg_rr_wait_io_event 
> /home/elmarco/src/qemu/cpus.c:1210
>     #6 0x557f756e90ad in qemu_tcg_rr_cpu_thread_fn 
> /home/elmarco/src/qemu/cpus.c:1536
>     #7 0x557f76e9f233 in qemu_thread_start 
> /home/elmarco/src/qemu/util/qemu-thread-posix.c:504
>     #8 0x7f77b4a11593 in start_thread (/lib64/libpthread.so.0+0x7593)
>
> Direct leak of 48 byte(s) in 1 object(s) allocated from:
>     #0 0x7f77c0668e50 in calloc (/lib64/libasan.so.5+0xeee50)
>     #1 0x7f77beb7b41d in g_malloc0 (/lib64/libglib-2.0.so.0+0x5241d)
>     #2 0x557f756df5bd in timer_new 
> /home/elmarco/src/qemu/include/qemu/timer.h:561
>     #3 0x557f756df5ee in timer_new_ns 
> /home/elmarco/src/qemu/include/qemu/timer.h:584
>     #4 0x557f756e4690 in start_tcg_kick_timer 
> /home/elmarco/src/qemu/cpus.c:965
>     #5 0x557f756e8616 in qemu_tcg_rr_cpu_thread_fn 
> /home/elmarco/src/qemu/cpus.c:1466
>     #6 0x557f76e9f233 in qemu_thread_start 
> /home/elmarco/src/qemu/util/qemu-thread-posix.c:504
>     #7 0x7f77b4a11593 in start_thread (/lib64/libpthread.so.0+0x7593)
>
> SUMMARY: AddressSanitizer: 96 byte(s) leaked in 2 allocation(s).
>
> Signed-off-by: Marc-André Lureau <address@hidden>
> ---
>  cpus.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/cpus.c b/cpus.c
> index 719788320f..0513c657f4 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -973,6 +973,7 @@ static void stop_tcg_kick_timer(void)
>      assert(!mttcg_enabled);
>      if (tcg_kick_vcpu_timer) {
>          timer_del(tcg_kick_vcpu_timer);
> +        timer_free(tcg_kick_vcpu_timer);
>          tcg_kick_vcpu_timer = NULL;
>      }
>  }

Arguably we should be stopping and starting the timer properly rather
than re-creating it every time. However that would complicate the logic
that is currently just using the presence of a timer reference to infer
activeness. So:

Acked-by: Alex Bennée <address@hidden>

--
Alex Bennée