[PATCH 21.11] examples/performance-thread: fix build with GCC 12

[PATCH 21.11] examples/performance-thread: fix build with GCC 12

[Kevin Traynor]

[1/2] Compiling C object examples/dpdk-pthrea...
formance-thread_pthread_shim_pthread_shim.c.o
../examples/performance-thread/pthread_shim/pthread_shim.c:
In function ‘pthread_setspecific’:
../examples/performance-thread/pthread_shim/pthread_shim.c:592:27:
warning: ‘data’ may be used uninitialized [-Wmaybe-uninitialized]
592 |    int rv =  lthread_setspecific((unsigned int)key, data);
    |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../examples/performance-thread/pthread_shim/pthread_shim.c:589:56:
note: accessing argument 2 of a function declared with attribute
‘access (none, 2)’
589 | int pthread_setspecific(pthread_key_t key, const void *data)
    |                                            ~~~~~~~~~~~~^~~~

This is a false positive as pthread_setspecific() does not read from
the (const void *) so we can squash the warning.

performance-thread example is already removed from DPDK main branch.

Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
---
 examples/performance-thread/pthread_shim/pthread_shim.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/examples/performance-thread/pthread_shim/pthread_shim.c b/examples/performance-thread/pthread_shim/pthread_shim.c
index bbc076584b..a44cb8244d 100644
--- a/examples/performance-thread/pthread_shim/pthread_shim.c
+++ b/examples/performance-thread/pthread_shim/pthread_shim.c
@@ -587,4 +587,9 @@ pthread_t pthread_self(void)
 }
 
+#if defined(RTE_TOOLCHAIN_GCC) && (GCC_VERSION >= 120000)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif
+
 int pthread_setspecific(pthread_key_t key, const void *data)
 {
@@ -596,4 +601,8 @@ int pthread_setspecific(pthread_key_t key, const void *data)
 }
 
+#if defined(RTE_TOOLCHAIN_GCC) && (GCC_VERSION >= 120000)
+#pragma GCC diagnostic pop
+#endif
+
 int pthread_spin_init(pthread_spinlock_t *a, int b)
 {
-- 
2.37.2

Re: [PATCH 21.11] examples/performance-thread: fix build with GCC 12

[David Marchand]

On Wed, Aug 24, 2022 at 11:58 AM Kevin Traynor <ktraynor@redhat.com> wrote:
>
> [1/2] Compiling C object examples/dpdk-pthrea...
> formance-thread_pthread_shim_pthread_shim.c.o
> ../examples/performance-thread/pthread_shim/pthread_shim.c:
> In function ‘pthread_setspecific’:
> ../examples/performance-thread/pthread_shim/pthread_shim.c:592:27:
> warning: ‘data’ may be used uninitialized [-Wmaybe-uninitialized]
> 592 |    int rv =  lthread_setspecific((unsigned int)key, data);
>     |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../examples/performance-thread/pthread_shim/pthread_shim.c:589:56:
> note: accessing argument 2 of a function declared with attribute
> ‘access (none, 2)’
> 589 | int pthread_setspecific(pthread_key_t key, const void *data)
>     |                                            ~~~~~~~~~~~~^~~~
>
> This is a false positive as pthread_setspecific() does not read from
> the (const void *) so we can squash the warning.
>
> performance-thread example is already removed from DPDK main branch.
>
> Signed-off-by: Kevin Traynor <ktraynor@redhat.com>

Another workaround would be to redirect calls to pthread_setspecific
to this function "overriden" function.
The same is done for pthread_exit (see pthread_exit_override).

But otherwise this patch seems good enough.


-- 
David Marchand

Re: [PATCH 21.11] examples/performance-thread: fix build with GCC 12

[Kevin Traynor]

On 24/08/2022 14:55, David Marchand wrote:
> On Wed, Aug 24, 2022 at 11:58 AM Kevin Traynor <ktraynor@redhat.com> wrote:
>>
>> [1/2] Compiling C object examples/dpdk-pthrea...
>> formance-thread_pthread_shim_pthread_shim.c.o
>> ../examples/performance-thread/pthread_shim/pthread_shim.c:
>> In function ‘pthread_setspecific’:
>> ../examples/performance-thread/pthread_shim/pthread_shim.c:592:27:
>> warning: ‘data’ may be used uninitialized [-Wmaybe-uninitialized]
>> 592 |    int rv =  lthread_setspecific((unsigned int)key, data);
>>      |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> ../examples/performance-thread/pthread_shim/pthread_shim.c:589:56:
>> note: accessing argument 2 of a function declared with attribute
>> ‘access (none, 2)’
>> 589 | int pthread_setspecific(pthread_key_t key, const void *data)
>>      |                                            ~~~~~~~~~~~~^~~~
>>
>> This is a false positive as pthread_setspecific() does not read from
>> the (const void *) so we can squash the warning.
>>
>> performance-thread example is already removed from DPDK main branch.
>>
>> Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
> 
> Another workaround would be to redirect calls to pthread_setspecific
> to this function "overriden" function.
> The same is done for pthread_exit (see pthread_exit_override).
> 
> But otherwise this patch seems good enough.
> 
> 

ok, thanks. I'll just keep the current workaround as neither are 
particularly pretty and the example was dropped soon after 21.11, so I 
don't think anyone cares too much about it.